Transportation and Energy Systems
in the U.S.
Nakicenovic, N.
IIASA Working Paper
WP-87-001
January 1987
Nakicenovic, N. (1987) Transportation and Energy Systems in the U.S. IIASA Working Paper. IIASA, Laxenburg, Austria,
WP-87-001 Copyright © 1987 by the author(s). http://pure.iiasa.ac.at/3050/
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Working Paper
TRANSPORTATION AND
ENERGY SYSTEMS IN THE U.S.
N. Nakicenovic
WP-87-001
January 1987
FllASA
kd:
International Institute for Applied Systems Analysis
Telephone: (0 2 2 3 6 ) 715 2 1 * 0
A-2361 Laxenburg
Telex: 0 7 9 1 3 7 iiasa a
Austria
Telefax: (0 2 2 36) 71313
TRANSPORTATION AND
ENERGY SYSTEMS IN THE U.S.
N. Nakicenovic
WP-87-001
January 1987
Working Papers are interim reports on work of the International Institute for Applied
Systems Analysis and have received only limited review. Views or opinions expressed
herein do not necessarily represent those of the Institute or of its National Member
Organizations.
Ffl
IIASA
bHd#
International Institute for Applied Systems Analysis
Telephone: (0 22 36) 715 21 * O
A-2361 Laxenburg O Austria
Telex: 079 137 iiasa a
Telefax: ( 0 22 36) 71313
PREFACE
This paper was prepared f o r the National Academy of Engineering Workshop on
'The Evaluation of Infrastructures", W o o d s Hole, U.S.A., 11-13 August 1986. It is
based on research conducted together with Arnulf Grubler within the scope of the
dynamics of Technology project. of the Technology, Economy, Society Program.
TABLE OF CONTENTS
Page
1 INTRODUCTION
2 TRANSPORTATION
2.1 A i r c r a f t
2.2 A u t o m o b i l e
2.3 Railmads
2.4 C a n a l s
2-5 T r a n s p o r t I n f r a s t r u c t u r e s
3 PRIMARY ENERGY
3-1 E n e r g y C o n s u m p t i o n
3.2 E n e r g y S u b s t i t u t i o n
3.3 Oil a n d N a t u r a l G a s P r o d u c t i o n
3.4 Oil a n d G a s T r a n s p o r t
4 CONCLUSIONS
LET OF FIGURES
Page
F i g u r e 2.1
World A i r T r a n s p o r t
- All
F i g u r e 2.2
World A i r T r a n s p o r t
- Logistic Plot.
F i g u r e 2.3
Passenger Aircraft Performance.
Operations.
F i g u r e 2.4 P e r f o r m a n c e of A i r c r a f t E n g i n e s .
F i g u r e 2.5
N u m b e r of Automobiles a n d R o a d H o r s e s (and Mules) i n US.
F i g u r e 2.6 S u b s t i t u t i o n of H o r s e s b y C a r s , US.
F i g u r e 2.7 All R o a d V e h i c l e s i n U s e , US.
F i g u r e 2.8 Mileage of all R o a d s , US.
F i g u r e 2.9
S u b s t i t u t i o n of U n s u r f a c e d b y S u r f a c e d R o a d s , US.
F i g u r e 2.10 Mileage of S u r f a c e d R o a d s , US.
F i g u r e 2.11 G r o w t h P u l s e i n Main R a i l T r a c k O p e r a t e d , US.
F i g u r e 2.12 S u b s t i t u t i o n of S t e a m b y D i e s e l Locomotives, US.
F i g u r e 2.13 L e n g t h of C a n a l s , US.
F i g u r e 2.14 S u b s t i t u t i o n of T r a n s p o r t I n f r a s t r u c t u r e s , US.
F i g u r e 2.15 I n t e r c i t y P a s s e n g e r T r a f f i c S u b s t i t u t i o n , US.
F i g u r e 3.1
P r i m a r y E n e r g y Consumption, U.S.
F i g u r e 3.2
P r i m a r y E n e r g y S u b s t i t u t i o n , US.
F i g u r e 3.3
N a t u r a l G a s P r o d u c t i o n f r o m Oil a n d G a s Wells, US.
F i g u r e 3.4 E n e r g y S u b s t i t u t i o n a n d G a s T e c h n o l o g i e s , U.S.
F i g u r e 3.5
C r u d e a n d P r o d u c t s Oil P i p e l i n e s L e n g t h , U.S.
F i g u r e 3.6 N a t u r a l G a s P i p e l i n e L e n g t h , U.S.
Transportation and Energy Systems in t h e U. S.
1 INTRODUCTION
The objective of t h i s p a p e r i s t o a s s e s s , on t h e b a s i s of a number of indicative
examples, t h e time needed t o build new a n d r e p l a c e old t r a n s p o r t a t i o n and e n e r g y
systems, and t h e i r i n f r a s t r u c t u r e s . Most of t h e examples are t a k e n from t h e United
S t a t e s , s i n c e t h e United States h a s b e e n one of t h e few c o u n t r i e s t o e x p e r i e n c e
most of t h e technological changes t h a t o c c u r r e d during t h e l a s t 200 y e a r s .
However, b e c a u s e most of t h e s e technological c h a n g e s were subsequently
disseminated throughout t h e world, t h e examples a l s o indicate t h e dynamics of t h e s e
p r o c e s s e s elsewhere.
Within t h e s c o p e of t h i s p a p e r , t h e use of t h e t e r m i n f r a s t r u c t u r e i s r a t h e r
narrow, r e f e r r i n g only t o t r a n s p o r t a t i o n a n d e n e r g y g r i d s a n d networks, and o t h e r
components of t h e s e two systems. These two systems are i n t e r e s t i n g because t h e y
played a c r u c i a l r o l e in t h e economic a n d technological development p r o c e s s , a r e
v e r y c a p i t a l intensive and, in g e n e r a l , h a v e long lifetimes. The analysis of t h e
historical development of t h e s e two systems will include a quantitative d e s c r i p t i o n of
performance improvement, t h e g e n e r a l evolution of a p a r t i c u l a r i n f r a s t r u c t u r e , and
t h e replacement of old b y new technologies and i n f r a s t r u c t u r e s in t e r m s of t h e i r
r e l a t i v e m a r k e t s h a r e s . W e use t h e t e r m performance as a multidimensional c o n c e p t
(i.e., as a v e c t o r r a t h e r t h a n a s c a l a r indicator) and, where a p p r o p r i a t e , measure
t h e size of a n i n f r a s t r u c t u r e as a function of time.
The f i r s t s e c t i o n d e s c r i b e s t h e evolution of t r a n s p o r t system and t h e i r r e l a t e d
i n f r a s t r u c t u r e s . The analysis starts, somewhat unconventionally, with t h e youngest
technologies, a i r c r a f t a n d airways, a n d ends with t h e oldest t r a n s p o r t networks c a n a l s and waterways. The second section d e s c r i b e s t h e evolution of e n e r g y
consumption a n d pipelines as a n example of dedicated t r a n s p o r t i n f r a s t r u c t u r e s .
2 TRANSPORTATION
2.1 Aircraft
A i r c r a f t are t h e most successful of t h e advanced modes of t r a n s p o r t a t i o n .
O t h e r c o n c e p t s of r a p i d t r a n s p o r t s u c h as v e r y high s p e e d t r a i n s h a v e shown some
limited s u c c e s s but are n o t as universally used as a i r c r a f t . In f a c t , t h e r a p i d
expansion of a i r t r a v e l during r e c e n t d e c a d e s h a s i t s r o o t s in t h e developments
achieved in aerodynamics and o t h e r sciences many decades ago, and especially in
t h e engineering achievements between t h e two World Wars. The DC-3 Airliner i s
often given a s t h e example of t h e f i r s t "modern" passenger t r a n s p o r t because in
many ways i t denotes t h e beginning of t h e "aircraft age". The u s e of a i r c r a f t f o r
t r a n s p o r t has increased e v e r since and t h e i r performance h a s improved by about
two o r d e r s of magnitude. Figure 2.1 shows the increase of a i r t r a n s p o r t in t h e world
measured in million passenger-kilometers p e r y e a r and r e f e r s t o all c a r r i e r
operations including those of t h e planned economies. The logistic function has been
fitted t o t h e actual d a t a and it indicates t h a t t h e inflection point in t h e growth of a i r
c a r r i e r operations o c c u r r e d about ten y e a r s a g o (i.e. about 1977). This means t h a t
a f t e r a very rapid, exponential growth period t h e r e is less than one doubling l e f t
until t h e estimated saturation level i s achieved a f t e r t h e y e a r 2000. The growth
r a t e has been declining f o r about ten y e a r s and will continue t o do s o until t h e total
volume of all operations levels off a f t e r t h e y e a r 2000 at about a 40 p e r c e n t higher
level than a t present.
Figure 2.2 shows t h e same d a t a and fitted logistic c u r v e transformed as
z / ( n z ) , where z denotes t h e actual volume of all operations in a given y e a r (from
Figure 2.1) and K is t h e estimated saturation level. The d a t a and t h e estimated
logistic t r e n d line a r e plotted in Figure 2.2 a s fractional s h a r e s of t h e saturation
Transformed in this
level, f = z / n , which simplifies t h e transformation t o f/(l-j').
way, the d a t a a p p e a r t o b e on a s t r a i g h t line, which is t h e estimated logistic
function.
P e r h a p s t h e most interesting result i s t h a t it took about 30 y e a r s until
world a i r t r a n s p o r t r e a c h e d i t s inflection point (i.e. o r about half of t h e estimated
saturation level) and t h a t within two decades saturation level would.be reached. The
crucial question implied by this r e s u l t i s what will happen a f t e r such a possible
saturation? Can w e e x p e c t a n o t h e r growth pulse, a decline, o r instability of
changing periods of growth and decline?
To understand t h e implications of a possible saturation in world a i r t r a n s p o r t
operations, i t i s necessary t o look a t t h e t r a n s p o r t system in g e n e r a l , comparing
aviation with o t h e r modes of t r a n s p o r t , and t o analyze t h e various components of t h e
a i r t r a n s p o r t system itself. The a i r c r a f t , a i r p o r t s and ground s e r v i c e s obviously
r e p r e s e n t t h e most important components of the a i r t r a n s p o r t i n f r a s t r u c t u r e .
Commercial aviation i n f r a s t r u c t u r e i s different from t h a t of o t h e r competing
t r a n s p o r t systems such a s r o a d s o r railways. Airports a r e distributed and not
connected as a r e pipelines o r roads, although a i r c r a f t r e p r e s e n t a n i n f r a s t r u c t u r e
of complex elements in t h e same way hospitals o r schools do.
There a r e a number of possible ways t o d e s c r i b e t h e global fleet of commercial
a i r t r a n s p o r t and how i t developed. An obvious d e s c r i p t o r of t h e f l e e t would b e t h e
number of a i r c r a f t in operation worldwide. In f a c t , this number increased from
about 3,000 in the 1950s t o almost 10,000 in t h e 1980s. However, during t h e same
time the performance o r c a r r y i n g capacity and speed of a i r c r a f t increased by about
two o r d e r s of magnitude. Thus, t h e size of t h e fleet i s not t h e most important
d e s c r i p t o r , since much of t h e t r a f f i c is allocated to t h e most productive a i r c r a f t
1 One general finding of a large number of studies i s that many growth processes follow
characteristic Sshaped curves. Logistic function i s one of the most widely applied Sshaped
growth curves and i s given by: z/(n-z)=exp(at +p), where t i s the independent variable usually
representing some unit of time, a and 8 are constants, z i s the actual level of growth achieved,
while n-z i s the amount of growth s t i l l t o be achieved before the saturation level n i s reached.
Taking logarithms of both sides gives the l e f t side of the equation t o be expressed a s a linear
function of time s o that the secular trend of a logistic growth process appears a s a straight line
when plotted in this way. Substituting f = z / n in the equation, expresses the growth process in
terms of fractional share f of the asymptotic level n reached, i.e. the equation becomes:
f/(l-f)-exp(at +p).
Figure 2.1
World Air T r a n s p o r t
operating between t h e l a r g e
and distribution system t o
between e l e c t r i c i t y g r i d s o r
t o high-voltage transmission
- All Operations.
hub-airports while o t h e r a i r c r a f t constitute t h e f e e d e r
destinations with lower t r a f f i c volume. The analogy
r o a d systems i s v e r y close - l a r g e a i r c r a f t c o r r e s p o n d
lines o r primary roads.
Fraction ( F =
X
0.99
Figure 2.2
World Air T r a n s p o r t
- Logistic Plot.
Figure 2.3 shows t h e improvement o v e r time of o n e important p e r f o r m a n c e
indicator f o r commercial p a s s e n g e r a i r c r a f t , i.e., t h e i n c r e a s e of c a r r y i n g
c a p a c i t y and s p e e d (often called productivity) measured in passenger-kilometers
p e r h o u r . E a c h point on t h e g r a p h indicates t h e p e r f o r m a n c e of a given a i r c r a f t
when used in commercial o p e r a t i o n s f o r t h e f i r s t time. F o r example, t h e DC-3 w a s
introduced in 1935 with a p e r f o r m a n c e of a b o u t 7,400 passenger-kilometers p e r
h o u r (about 21 p a s s e n g e r s at a b o u t 350 km/h) whereas t h e B747 w a s introduced i n
1969 with a p e r f o r m a n c e of a b o u t 500,000 passenger-kilometers p e r h o u r (about 500
p a s s e n g e r s at about 1,000 km/h). The l a r g e s t , c u r r e n t B747s c a n c a r r y almost 700
p a s s e n g e r s a n d are t h e r e f o r e a b o u t 100 times as productive as t h e DC-3 50 y e a r s
ago. The u p p e r c u r v e r e p r e s e n t s a kind of "performance feasibility" f r o n t i e r f o r
p a s s e n g e r a i r c r a f t , s i n c e t h e p e r f o r m a n c e of all commercial a i r t r a n s p o r t s at t h e
time t h e y w e r e introduced i s e i t h e r on o r below t h e c u r v e . F u r t h e r m o r e , all
commercially successful long-range a i r c r a f t are on t h e p e r f o r m a n c e feasibility
c u r v e , while all o t h e r planes lie below t h e c u r v e . Thus, at a n y given time t h e r e
a p p e a r s to b e only o n e a p p r o p r i a t e productivity specification f o r long-range
p a s s e n g e r planes. Since t h e more r e c e n t jet t r a n s p o r t s all fly at a b o u t t h e same
s p e e d , t h e a p p r o p r i a t e design f o r a new, hypothetical long-range t r a n s p o r t should
allow f o r a c a p a c i t y of more t h a n 700 passengers. According to t h e estimated
c u r v e , t h e asymptotic c a p a c i t y of t h e l a r g e s t a i r c r a f t i s a b o u t 1,200 p a s s e n g e r s at
subsonic s p e e d (i.e. 1,200 p a s s e n g e r kilometers p e r h o u r o r 200,000 p a s s e n g e r
kilometers p e r y e a r ) . Another i n t e r e s t i n g f e a t u r e in Figure 2.3 i s t h a t t h e
productivity of all p a s s e n g e r a i r c r a f t i s confined within a r a t h e r n a r r o w band
1
Fraction ( F =
Figure 2.3
X
Passenger Aircraft Performance.
between the performance feasibility c u r v e and a "parallel" logistic c u r v e with a lag
of about nine years. This "parallel" logistic c u r v e coincides with t h e growth of t h e
world a i r t r a n s p o r t from Figure 2.2.
It took about 33 y e a r s f o r the performance of the most productive a i r c r a f t t o
i n c r e a s e from about one p e r c e n t of t h e estimated asymptotic performance t o about
half t h a t performance (e.g. t h e DC-3 r e p r e s e n t s the one-percent achievement and
the B747 roughly the 50-percent mark). In many ways, t h e achievement of the 50
p e r c e n t level r e p r e s e n t s a s t r u c t u r a l change in t h e development of the whole
passenger a i r c r a f t industry and airlines. Since w e a r e dealing with S s h a p e d growth
(i.e. a logistic c u r v e ) t h e growth p r o c e s s is exponential until t h e inflection point
(i.e. the 50 p e r c e n t level) is achieved. This means t h a t at the beginning t h e r e a r e
many doublings in the productivity of a i r c r a f t within periods of only a few years.
However, once t h e inflection point (the 50-percent level) is r e a c h e d , t h e r e i s only
-
2 We call the elapsed time between the one and 50 percent points A t , i.e. in t h i s example A t
33
years. Due t o the symmetry of the logistic function, the same time i s required for the increase
from 50 t o 99 percent of the saturation level.
one doubling l e f t until t h e s a t u r a t i o n level i s r e a c h e d . In t h e example from Figure
2.3, t h i s development p h a s e o c c u r r e d in 1969 with t h e introduction of t h e B747.
Since t h e B747 could in principle b e s t r e t c h e d by a b o u t a f a c t o r of two, i t could a l s o
b e t h e long-range a i r c r a f t during t h e n e x t two decades. T h e r e a f t e r , a new p h a s e of
growth i s conceivable with e i t h e r l a r g e r o r f a s t e r long-range a i r c r a f t a n d in t h e
more distant f u t u r e possibly both. Before t h e inflection point, s t r e t c h i n g does n o t
help f o r more than a few y e a r s due to r a t h e r f r e q u e n t doublings in productivity s o
t h a t principally new solutions are necessary. This a l s o means t h a t a wrong model on
t h e m a r k e t c a n b e a c r u c i a l b u t n e v e r t h e l e s s r e v e r s i b l e mistake provided t h a t t h e
manufacturer h a s l a r g e enough r e s o u r c e s a t h i s disposal t o launch a new, improved
performance model on t h e m a r k e t a f t e r a few y e a r s . However, a f t e r t h e inflection
point this i s no l o n g e r a possible s t r a t e g y since those a i r c r a f t t h a t are successful
c a n b e s t r e t c h e d t o meet t h e m a r k e t demand through s a t u r a t i o n . T h e r e f o r e , toward
t h e l a t e 1960s designing new long-range t r a n s p o r t suddenly became r i s k i e r than
b e f o r e s i n c e a second c h a n c e of launching a new model a f t e r a few y e a r s was n o
l o n g e r possible. The B747, f o r example, had t h e a p p r o p r i a t e productivity, while two
o t h e r competitors, t h e DC-10 a n d L l O l l were t o o small. Launching a 700 to 800
p a s s e n g e r a i r c r a f t in t h e n e a r f u t u r e could constitute a g r e a t r i s k s i n c e a s t r e t c h e d
B747 c a n d o t h e same job. A smaller long-range a i r c r a f t would most likely constitute
a f a i l u r e as well since i t would fall s h o r t of t h e m a r k e t requirements. The design of
a s u p e r s o n i c a i r c r a f t with a c a p a c i t y f o r 300 t o 400 p a s s e n g e r s , o r a hypersonic
t r a n s p o r t with s a y 200 t o 250 p a s s e n g e r s , may t h e r e f o r e b e a b e t t e r s t r a t e g y f o r
t h e f i r s t y e a r s of t h e n e x t c e n t u r y . To some e x t e n t this a l s o explains why Concorde
cannot b e a commercial s u c c e s s - with a c a p a c i t y of 100 p a s s e n g e r s i t w a s 1 5 0
p a s s e n g e r s s h o r t of being a s e r i o u s competitor t o t h e B747.
Figure 2.4 shows t h e p e r f o r m a n c e improvement of civil a i r c r a f t engines s i n c e
t h e beginning of aviation. The f i r s t piston engine visible on t h e plot i s t h e F r e n c h
Antoinette engine r a t e d a t 5 0 h p in 1906 a n d t h e l a s t i s t h e American Wright Turbo
Compound r a t e d at 3400 h p in 1950. These r e p r e s e n t a n improvement in power of
almost two o r d e r s of magnitude during a p e r i o d of 44 y e a r s , a n d a b o u t 90 p e r c e n t of
t h e estimated s a t u r a t i o n level f o r piston engines at a b o u t 3800 hp. A p a r a l l e l
development in t h e maximal t h r u s t of j e t engines follows with a lag of a b o u t 30 y e a r s :
s t a r t i n g in 1944 with t h e German J u n k e r s Juno 004 ( r a t e d at 900 kg) a n d ending with
t h e American P r a t t a n d Whitney JT9D in t h e e a r l y 1980s with 9 0 p e r c e n t of t h e
estimated s a t u r a t i o n level of a b o u t 29000 kg. Both pulses in t h e improvement of
a i r c r a f t engines are c h a r a c t e r i z e d with a A t of about 30 y e a r s . The midpoints of
t h e two pulses o c c u r r e d in 1936 a n d 1966 (i.e., t h e r e s p e c t i v e inflection points) a n d
coincide with t h e introduction of t h e DC-3 and B747. In f a c t , t h e P r a t t and Whitney
Twin Wasp, introduced in 1930, became t h e power plant f o r t h e DC-3. I t a l s o s e r v e d
as t h e basis-engine f o r subsequent and more powerful d e r i v a t i v e s s u c h as t h e Wasp
Major introduced in 1945 toward t h e end of t h e a i r c r a f t piston engine era. Thus,
c e r t a i n p a r a l l e l s are visible t o t h e dynamics of p a s s e n g e r a i r c r a f t development
beyond t h e obvious similarity in t h e time c o n s t a n t (At of a b o u t 30 y e a r s ) . Namely,
t h o s e engines introduced slightly b e f o r e t h e inflection point, s u c h as t h e Twin Wasp,
a r e "stretched" by doubling t h e cylinder rows t o i n c r e a s e t h e power. The Wright
T u r b o Compound r e p r e s e n t s t h e l a s t refinement in a i r c r a f t piston engines, t h e major
additional f e a t u r e being t h a t turbo-charging was used to d e r i v e shaft-power,
otherwise t h e engine w a s a d i r e c t d e r i v a t i v e from t h e Wright Cyclone s e r i e s
introduced in t h e e a r l y 1930s with Cyclone 9 (which originally powered t h e DC-2).
This r e s u l t indicates t h a t t h e time constant f o r t h e development of p a s s e n g e r
a i r c r a f t as one of t h e most modern t r a n s p o r t a t i o n modes a p p e a r s t o b e a b o u t 3 0
y e a r s . A s mentioned above, t h e s t a n d a r d industry design emerged during t h e
Fraction ( F =
X
--
-------
Pistons (HP)
(K = 3800)
--
---
Jets
-Max Thrust Kg -(K = 29,000)
- --
--
---
----
d-
--------
*
------
--
--------
-----
---
I
I
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
A. Griibler. 1986
Figure 2.4
P e r f o r m a n c e of A i r c r a f t Engines.
depression y e a r s (i.e., t h e 1930s). Thirty y e a r s l a t e r t h e B747, t h e f i r s t wide-body
jet t o e n t e r s e r v i c e , r e p r e s e n t e d one of t h e most significant improvements in
commercial t r a n s p o r t and i t s productivity r e p r e s e n t e d half of t h e estimated
industry s a t u r a t i o n level t h a t may b e a p p r o a c h e d toward t h e end of t h i s c e n t u r y .
Thus, within a period of 6 0 y e a r s t h e life c y c l e i s completed, from standardization
and subsequent r a p i d growth c h a r a c t e r i z e d b y numerous improvements, through t h e
inflection point when t h e emphasis c h a n g e s t o competition c h a r a c t e r i z e d b y c o s t
reductions a n d rationalization. These c h a r a c t e r i s t i c s of t h e industry, including
s t e a d y performance improvement, are well illustrated by t h e development of t h e
B747 line. Next we will investigate t h e development of a n o l d e r system t h a t i s a
s t r o n g competitor f o r t h e a i r l i n e s in long-distance p a s s e n g e r t r a n s p o r t
the
automobile.
-
2.2 Automobile
A t t h e beginning of t h e c e n t u r y , v e r y few proponents of t h e automobile
envisaged t h a t i t would develop and disseminate throughout t h e world s o rapidly
during t h e last 100 years. But the f i r s t horseless c a r r i a g e s already posed a n
alternative t o t h e horse-drawn buggies and wagons. A s a commercial and
r e c r e a t i o n a l vehicle, t h e motor car offered many potential advantages compared t o
o t h e r modes of transportation, especially o v e r animal-drawn vehicles. P e r h a p s t h e
most important advantage was t h e possibility t o i n c r e a s e t h e radius of local
t r a n s p o r t ; being faster t h e automobile allowed many e n t r e p r e n e u r s to expand t h e i r
c i r c l e of customers and offered a more flexible mode of business and leisure
transport.
A t t h e beginning t h e r a i l r o a d s were not challenged by t h e automobile, but
r a t h e r helped t h e i r expansion since they offered a n efficient form of long-distance
t r a n s p o r t t h a t combined w e l l with t h e use of motor vehicles f o r local, urban and
r u r a l road t r a n s p o r t . Within a few decades, however, t h e automobile became a n
important form of t r a n s p o r t f o r both local and long-distance passenger t r a v e l in t h e
United States. Since t h e 1930s up t o t h e present, t h e total mileage traveled by
automobiles, and motor vehicles in general, was divided almost equally between
r u r a l and urban travel.
The automobile had a relatively l a t e s t a r t in the United S t a t e s compared with
European countries (e.g. France, Germany and t h e United Kingdom). In 1894 f o u r
motor vehicles were r e c o r d e d t o be in use in t h e United States. However, t h e
expansion of the automobile fleet' t h e r e a f t e r was impressive - 1 6 vehicles were in
use in 1896, 90 in 1897, 8,000 in 1900, almost half a million ten y e a r s l a t e r and more
than one million a f t e r a n o t h e r two y e a r s . Thus, both in terms of production and
number of vehicles in use, t h e United S t a t e s quickly surpassed European countries.
Figure 2.5 shows t h e rapid increase in t h e number of cars used in t h e United
States. By t h e 1920s m o r e than ten million automobiles were in use on American
roads and t h e 100 million mark was surpassed in 1970. Figure 2.5 also shows t h a t
the expansion of the automobile f l e e t i s c h a r a c t e r i z e d by two distinct s e c u l a r t r e n d s
with a n inflection in t h e 1930s followed by less rapid growth r a t e s . Since the t w o
s e c u l a r t r e n d s of the c u r v e a p p e a r to be roughly linear on t h e logarithmic scale in
Figure 2.5, the automobile fleet evolved through two exponential p u l s e s . Our
working hypothesis i s t h a t t h e two t r e n d s indicate two different phases of
dissemination of motor vehicles in t h e United States. The f i r s t c h a r a c t e r i z e s t h e
substitution of horse-drawn road vehicles, and t h e second the actual growth of r o a d
t r a n s p o r t a f t e r o t h e r , animal-drawn vehicles essentially disappeared from American
roads. Only a f t e r t h e completion of this substitution p r o c e s s did t h e automobile
emerge a s a n important competitor to t h e railroads f o r t h e long-distance movement
of people and goods, and p e r h a p s , also a s a competitor t o urban transportation
modes, such as t h e tram, subway o r local t r a i n . Thus, t h e f i r s t expansion phase is
more rapid since i t r e p r e s e n t s a "market takeover", whereas t h e second r e p r e s e n t s
t h e actual growth of t h e r o a d vehicle fleets and t h e i r associated i n f r a s t r u c t u r e s
such as highway systems.
Due t o t h e obvious problems associated with t h e lack of historical r e c o r d s
about t h e e x a c t number of horse-drawn vehicles in the United S t a t e s during the f i r s t
decades a f t e r the introduction of t h e automobile in 1895, w e c a n only approximately
d e s c r i b e t h e assumed substitution of the h o r s e by t h e motor car during t h e f i r s t ,
Figure 2.5
Number of Automobiles a n d Road H o r s e s (and Mules) in US.
more r a p i d , expansion p h a s e of t h e motor vehicle fleets. A s a r o u g h approximation
of t h i s substitution p r o c e s s , w e use t h e number of d r a f t animals ( r o a d h o r s e s and
mules) a n d automobiles given in Figure 2.5. Sometimes h o r s e a n d saddle were used
a s a "road vehicle", b u t o f t e n more t h a n o n e h o r s e was used t o pull buggies and
wagons. City omnibuses r e q u i r e d a b o u t 15 h o r s e s t o b e in u s e t h e whole d a y a n d a
s t a g e c o a c h p r o b a b l y e v e n more, s i n c e t h e h o r s e s were r e p l a c e d a t e a c h s t a t i o n .
Thus, Figure 2.5 may overemphasize t h e number of horse-drawn vehicles if t h e
number of d r a f t animals i s used as a p r o x y f o r t h e number of v e h i c l e s a c t u a l l y in
use. On t h e o t h e r hand, w e h a v e not included farm work animals in Figure 2.5,
although c e r t a i n l y f a r m h o r s e s were a l s o used as a means of t r a n s p o r t , especially in
t h e r u r a l a r e a s . Thus, t h e disadvantage of t h i s rough comparison of t h e number of
animal-drawn vehicles a n d motor cars i s t h a t t h e e s t i m a t e s of non-farm h o r s e s a n d
mules a r e c e r t a i n l y not v e r y a c c u r a t e and are unevenly s p a c e d in time. Despite t h i s
disadvantage, Figure 2.6 i n d i c a t e s t h a t t h e automobile r e p l a c e d h o r s e - a n d muledrawn r o a d vehicles d u r i n g a r e l a t i v e l y s h o r t p e r i o d and t h a t t h e substitution
p r o c e s s p r o c e e d e d along a logistic path.
Motor vehicles a c h i e v e d a one-percent
3 One g e n e r a l f i n d i n g of a l a r g e number of s t u d i e s i s t h a t s u b s t i t u t i o n o f an old t e c h n o l o g y b y a new
one, e x p r e s s e d i n f r a c t i o n a l t e r m s , f o l l o w s c h a r a c t e r i s t i c S s h a p e d c u r v e s . F i s h e r a n d P r y
(1971) f o r m u l a t e d a s i m p l e b u t p o w e r f u l model of t e c h n o l o g i c a l s u b s t i t u t i o n b y p o s t u l a t i n g t h a t
t h e r e p l a c e m e n t of a n old by a new t e c h n o l o g y p r o c e e d s along t h e l o g i s t i c g r o w t h c u r v e :
f/(l-f ) = e x p ( a t +H), w h e r e t i s t h e i n d e p e n d e n t v a r i a b l e u s u a l l y r e p r e s e n t i n g s o m e u n i t of t i m e ,
a a n d @ a r e c o n s t a n t s , is t h e f r a c t i o n a l m a r k e t s h a r e of t h e n e w c o m p e t i t o r , w h i l e 1-f i s t h a t of
t h e old one.
Figure 2.6
Substitution of Horses by C a r s , US.
s h a r e in r o a d vehicles s h o r t l y a f t e r 1900, and a 5 0 p e r c e n t s h a r e in 1917. A
complete t a k e o v e r of t h e "market" o c c u r r e d in 1930 with 2 3 million cars o v e r 0.3
million r o a d h o r s e s and mules compared t o almost two million t e n y e a r s e a r l i e r . This
r e s u l t indicates t h a t t h e inflection point of t h e s e c u l a r t r e n d of r e g i s t e r e d c a r s
from Figure 2.5 actually coincides with t h e end of t h e substitution of animal-drawn
r o a d vehicles a n d explains t h e "saturation" in t h e growth of motor vehicles
p e r c e i v e d b y many a n a l y s t s during t h e l a t e 1920s and e a r l y 1930s. This p e r c e i v e d
s a t u r a t i o n marks t h e beginning of a new p h a s e in t h e motorization of America, with
growth rates comparable t o t h o s e of t h e expansion of horse-drawn vehicles b e f o r e
t h e automobile age. S e e n from t h i s p e r s p e c t i v e , t h e growth in t h e number of a l l
road vehicles i s a continuous p r o c e s s o v e r t h e e n t i r e p e r i o d from 1850 t o d a t e .
Figure 2.7 shows t h e s e c u l a r i n c r e a s e of all r o a d vehicles, horse-drawn and motor
powered, as a logistic growth p r o c e s s with a n a p p a r e n t s a t u r a t i o n level of a b o u t 350
million vehicles a f t e r t h e y e a r 2030 a n d A t of a b o u t 100 y e a r s .
Thus, w e are dealing with two simultaneous p r o c e s s e s , t h e growth of r o a d
t r a n s p o r t in g e n e r a l a n d t h e substitution of h o r s e c a r r i a g e s and wagons by
automobiles. Because t h e s e two s e c u l a r developments o v e r l a p in time t h e y t o g e t h e r
have t h e e f f e c t of producing two growth t r e n d s in t h e automobile f l e e t with a n
inflection point in t h e 1930s marking t h e s t r u c t u r a l c h a n g e in t h e composition of t h e
r o a d vehicle f l e e t s , b u t only one logistic growth t r e n d f o r a l l r o a d vehicles. Thus,
like a i r c r a f t , r o a d vehicles constitute a kind of d i s t r i b u t e d i n f r a s t r u c t u r e t h a t
expands in time as one connected system.
Figure 2.7
A l l Road Vehicles in Use, US.
In f a c t , both a i r a n d r o a d t r a n s p o r t systems r e q u i r e e l a b o r a t e a n d
sophisticated i n f r a s t r u c t u r e s . P e r h a p s t h e most obvious examples are a i r p o r t s a n d
supporting ground systems f o r a i r c r a f t , and r o a d s a n d s e r v i c e i n f r a s t r u c t u r e f o r
r o a d vehicles. In t h e c a s e of t r a i n s a n d a i r c r a f t i t i s self evident t h a t a i r p o r t s a n d
r a i l r o a d s were c o n s t r u c t e d with t h e single p u r p o s e of providing t h e i n f r a s t r u c t u r e
f o r t h e s e t r a n s p o r t modes. However, in t h e case of t h e automobile i t i s not s o c l e a r
w h e t h e r t h e r o a d s provided t h e niche into which t h e motor car e x p a n d e d o r if good
r o a d s had to b e developed b e c a u s e t h e car f l e e t s were expanding. Whether t h e
automobile c a u s e d t h e n e e d f o r good r o a d s , o r t h e c o n s t r u c t i o n of good r o a d s
c a u s e d t h e development of t h e automobile i n d u s t r y (an argument a l r e a d y d e b a t e d in
t h e 1930s, see e.g. Epstein, 1928). t h e expansion of r o a d vehicle f l e e t s i s p a r a l l e l e d
b y t h e mileage growth of s u r f a c e d r o a d s , although t h e t o t a l mileage of a l l r o a d s
i n c r e a s e d v e r y slowly from 3.16 million miles in 1 9 2 1 t o 3.85 million miles in 1981.
Figure 2.8 shows t h e t o t a l r o a d mileage in t h e United States a n d t h e mileage of
u r b a n streets ( e a r l i e r defined as municipal s t r e e t s ) , r u r a l r o a d s a n d a l l u r b a n a n d
r u r a l s u r f a c e d r o a d s (bituminous p e n e t r a t i o n , a s p h a l t , c o n c r e t e , wood, s t o n e a n d
o t h e r ) . The f i g u r e i l l u s t r a t e s t h a t t h e growth of s u r f a c e d r o a d s p a r a l l e l e d t h e
growth of all r o a d vehicle f l e e t s while t h e mileage of a l l r o a d s i n c r e a s e d v e r y
slowly. However, t h e expansion of s u r f a c e d r o a d s p r e c e d e d t h e expansion of motor
vehicles. In 1 9 0 5 e i g h t p e r c e n t of all r o a d s were s u r f a c e d , b u t less t h a n 8 0
thousand motor vehicles were in use compared t o a b o u t 3.3 million r o a d h o r s e s a n d
mules (in addition t o t h e 22 million d r a f t animals used f o r farming). Thus, t h e e a r l y
s u r f a c e d r o a d s were developed f o r h o r s e s a n d not automobiles, b u t m o t o r v e h i c l e s
1000 fllles
J
10
*
t
3
-
rural
surfaced/
Figure 2.8
Mileage of all Roads, US.
quickly expanded into t h e growing i n f r a s t r u c t u r e .
Figure 2.9 shows t h e substitution of unsurfaced b y s u r f a c e d r o a d s . In 1 9 1 0
a b o u t 1 0 p e r c e n t of all r o a d s were s u r f a c e d , during t h e 1940s a b o u t o n e half, a n d
today a b o u t 9 0 p e r c e n t are s u r f a c e d , s o t h a t t h e substitution p r o c e s s l a s t e d (i.e. A t
is) a b o u t 75 y e a r s . T h e r e f o r e , we c a n conclude t h a t t h e introduction of s u r f a c e d
r o a d s p r e c e d e d t h e introduction of motor vehicles in t h e United S t a t e s , b u t t h a t t h e
f i r s t rapid-growth p h a s e of motor vehicle f l e e t s o c c u r r e d while l e s s t h a n one half of
American r o a d s were s u i t a b l e f o r t h e i r use. I t i s a l s o i n t e r e s t i n g to n o t e t h a t t h e
substitution p r o c e s s does n o t r e f l e c t t h e vigorous r o a d c o n s t r u c t i o n e f f o r t a f t e r
t h e d e p r e s s i o n y e a r s in t h e United S t a t e s , b u t r a t h e r i n d i c a t e s a l a c k of s u c h e f f o r t
d u r i n g t h e 1910s a n d 1920s b e c a u s e t h e a c t u a l expansion of s u r f a c e d mileage i s
somewhat below t h e long-term t r e n d during t h e s e two d e c a d e s . A similar
underexpansion o c c u r r e d d u r i n g t h e e a r l y 1970s, b u t a p p e a r s t o h a v e b e e n
r e a b s o r b e d d u r i n g t h e l a s t few y e a r s . This i s a r e a s s u r i n g r e s u l t s i n c e i t confirms
t h e o b s e r v a t i o n t h a t i n f r a s t r u c t u r e i s a p r e r e q u i s i t e f o r t h e expansion of t r a n s p o r t
systems. R a i l r o a d s a n d a i r p o r t s h a d to b e c o n s t r u c t e d f o r t r a i n s a n d a i r c r a f t a n d ,
in t h e same way, s u r f a c e d r o a d s were r e q u i r e d f o r t h e widespread use of motor
vehicles. Figure 2.10 shows t h e i n c r e a s e of s u r f a c e d r o a d mileage as a logistic
growth p r o c e s s with a s a t u r a t i o n level of a b o u t 3.5 million miles (almost r e a c h e d
with 3.4 million miles today) t h a t p a r a l l e l s t h e substitution p r o c e s s of unsurfaced b y
s u r f a c e d r o a d s from Figure 2.9. Thus, s u r f a c e d r o a d s , as a n important
i n f r a s t r u c t u r e f o r r o a d t r a n s p o r t , a p p e a r to b e in s a t u r a t i o n today, while t h e
automobile f l e e t i s s t i l l growing a n d should r e a c h i t s estimated s a t u r a t i o n p h a s e in
about 50 years.
Figure 2.9
Substitution of Unsurfaced b y S u r f a c e d Roads, US.
Figure 2.10 Mileage of S u r f a c e d Roads, US.
2.3 Railroads
W e h a v e s e e n t h a t a i r t r a n s p o r t a n d t h e automobile are s t i l l expanding modes of
p a s s e n g e r t r a v e l . Railroads, on t h e o t h e r hand, are now in t h e post-saturation
development phase. In t e r m s of i n t e r c i t y p a s s e n g e r t r a f f i c in t h e United S t a t e s ,
t h e i r position vis-a-vie a i r c r a f t a n d t h e automobile i s being e r o d e d . I t i s symbolic
of t h i s d e c a y p r o c e s s t h a t t h e t r a n s c o n t i n e n t a l railway s e r v i c e h a s b e e n
discontinued in t h e U.S. While widespread a i r t r a v e l i s only a b o u t 5 0 y e a r s old a n d
t h e f i r s t automobile p e r h a p s about 1 0 0 y e a r s , t h e f i r s t r a i l r o a d s of significant
length were introduced 5 0 y e a r s e a r l i e r , o r more t h a n 1 5 0 y e a r s ago. Although
r a i l r o a d s were also developed l a r g e l y in E u r o p e , like t h e automobile t h e y h a d t h e i r
most d r a m a t i c growth in t h e United States. By 1840, o r more t h a n t e n y e a r s a f t e r
t h e f i r s t commercial lines went i n t o s e r v i c e , t h e United S t a t e s h a d almost 4,500 km
of r a i l r o a d compared t o E u r o p e ' s 3,000 km (see Taylor, 1951).
The Baltimore and Ohio Railroad, p r o b a b l y t h e f i r s t commercial r a i l r o a d in t h e
United S t a t e s , w a s c h a r t e r e d in 1829; two y e a r s l a t e r i t had 13 miles of t r a c k in
o p e r a t i o n . Many p r o j e c t s soon followed. In 1833 t h e Charleston and Hamburg
Railroad along t h e Savannah R i v e r r o u t e was t h e longest r a i l r o a d in t h e world u n d e r
single management with 1 2 6 miles of t r a c k . By 1935, t h r e e Boston r a i l r o a d s were in
o p e r a t i o n , o n e t o Lowell, o n e to W o r c e s t e r and t h e t h i r d to P r o v i d e n c e .
To a n e x t e n t , t h e e a r l y railway lines were f e e d e r lines f o r c a n a l and waterway
t r a n s p o r t systems in much t h e same way as t h e e a r l y commercial motor vehicles
were f o r railways. Tramways (as e a r l y dedicated t r a c k s with animal-drawn o r steam
t r a i n s were called) in t h e Pennsylvania coal fields augmented c a n a l t r a f f i c , and some
of t h e f i r s t r a i l r o a d s connecting t o t h e E r i e Canal originally s e r v e d as b r a n c h lines
f o r t h a t canal. In f a c t t h e e a r l y r a i l r o a d s were not allowed t o compete with t h e E r i e
Canal. But even t h e s e e a r l i e s t r a i l r o a d s were l a r g e l y independent t r a n s p o r t a g e n t s
and proved t o be s t u r d y r i v a l s f o r t h e o l d e r canals. Thus railways were both f e e d e r
lines f o r canals where t h e y could not compete with t h e canals, but a l s o provided
a l t e r n a t i v e t r a f f i c r o u t e s , and consequently d i r e c t competition, t o c a n a l s a n d
turnpikes. F o r example, t h e Boston and Worcester Railway w a s a competitor of t h e
Blackstone Canal, and when completed, t h e Providence and Worcester Railroad p u t
t h i s c a n a l out of business. The Baltimore a n d Ohio Railroad took business away from
t h e Chesapeake and Ohio Canal, and t h e Charleston and Hamburg Railroad w a s
designed t o , and did to some e x t e n t , d i v e r t t r a f f i c from t h e lower Savannah R i v e r .
This i s again analogous t o t h e competition between motor vehicles a n d r a i l r o a d s , and
t h e eventual replacement of t r a i n s by motor vehicles in some m a r k e t segments, and
t h e symbiotic development of e a r l y motor vehicles as a f e e d e r system t o t h e
r a i l r o a d network.
S t a r t i n g in t h e 1830s, t h e expansion of t h e r a i l r o a d s in t h e United S t a t e s w a s
v e r y r a p i d f o r almost 100 y e a r s . This growth p r o c e s s i s illustrated in Figure 2.11,
J ~ h i c hshows t h e i n c r e a s e in o p e r a t e d mileage of f i r s t and o t h e r main t r a c k s in t h e
United S t a t e s s i n c e 1835. The mileage i n c r e a s e d as a single logistic pulse r e a c h i n g
s a t u r a t i o n in 1929 with a At of about 5 0 y e a r s .
FRRCTION (F=X/KI
Figure 2.11 Growth Pulse in Main Rail Track Operated, US.
I t declined logistically t h e r e a f t e r with a At of about 125 y e a r s . The increase in
terms of t h e actual length of o p e r a t e d main t r a c k i n f r a s t r u c t u r e , was from about
4,500 km (less than 3,000 mi) in 1840 t o o v e r 480,000 km (about 300,000 mi) in 1929;
about two o r d e r s of magnitude in 90 y e a r s . In comparison, t h e decline w a s a r a t h e r
slow process: by t h e 1980s t h e length of main t r a c k actually in operation d e c r e a s e d
by about one third t o some 320,000 km (about 200,000 mi). Thus, t h e phase of
decline (about 50 y e a r s ) a p p e a r s t o be slower than t h e growth phase probably
because older technologies and i n f r a s t r u c t u r e s e n t e r e d new niches a f t e r t h e
saturation and displacement by new competitors. For example, sailing ships, wood
f i r e s and h o r s e riding have all become favorite leisure time and sporting activities
although in t h e i r original markets were replaced by new technologies long ago.
Thus, in this sense t h e railways may e n t e r a new e r a of use although they have
virtually lost any significance as a mode of intercity passenger travel. Local
passenger t r a f f i c and t o u r i s t cruises (perhaps similar t o ocean cruises) may be
alternative uses f o r this l a r g e i n f r a s t r u c t u r e in t h e future. Some canals a r e
a l r e a d y serving such a purpose although they have not been profitable a s a means
of t r a n s p o r t since the hay days of railroads. But both canals and railroads still
offer efficient t r a n s p o r t f o r low-value goods ( p e r unit weight and/or volume).
Many technological improvements were introduced in the United S t a t e s during
t h e f i r s t decades of t h e r a i l r o a d expansion. Most of t h e e a r l y American railroads
adopted wooden r a i l s often 20 t o 25 f e e t long capped with a n iron s t r a p o r b a r . In
1831 R o b e r t I. Stevens o r d e r e d iron T-rails from England and installed them on t h e
New J e r s e y Railroad (see Taylor, 1962), but i t was not until t h e 1860s t h a t T-rails
became a prominent design f e a t u r e on American railroads. In 1847 they became
mandatory in t h e s t a t e of New York, although wooden r a i l s were still in use on t h e
western r o u t e s then under construction. Iron r a i l s were a significant improvement
since they made the use of heavier locomotives and loads possible and t h e r e b y
increased t h e efficiency of r a i l t r a n s p o r t . L a t e r , t h e iron r a i l s were substituted by
steel. Thus, t h e basic construction materials in r a i l r o a d i n f r a s t r u c t u r e were
shifted from wood t o l a r g e r s h a r e s of initially iron and l a t e r steel. A t t h e same
time, t h e e n e r g y s o u r c e s also changed from t h e d r a f t animals t h a t were used in t h e
f i r s t tramways t o steam locomotives fired by wood, which then remained t h e
principal fuel used by r a i l r o a d s until about 1870 ( S h u r r and Natschert, 1960). Wood
w a s then replaced by coal and l a t e r steam locomotives in general were replaced by
diesel ones. Figure 2.12 shows t h e substitution of steam by diesel locomotives. The
f i r s t diesel locomotive w a s introduced in 1925 during t h e time when t h e total number
of locomotives peaked a t about 69,000 and a few y e a r s b e f o r e t h e length of main
t r a c k in operation r e a c h e d i t s maximum and s t a r t e d t o decline. Some e l e c t r i c
locomotives were introduced e a r l i e r but they n e v e r gained any importance in t h e
United S t a t e s and always stayed below a two p e r c e n t s h a r e in t h e total locomotive
fleet. The replacement of steam by diesel locomotives w a s a swift p r o c e s s t h a t
lasted slightly longer than 20 y e a r s (a little s h o r t e r than t h e time taken f o r t h e
substitution of h o r s e s by automobiles t h a t lasted less than 30 years). In 1938 diesel
locomotives r e a c h e d a one-precent s h a r e in total locomotives and by the 1960s more
than a 99 p e r c e n t s h a r e . Thus, while t h e substitution of steam by diesel locomotives
was a f a s t technological change in t h e composition of t h e fleet, t h e continuous
i n c r e a s e in performance of t h e railroad t r a n s p o r t system i s c h a r a c t e r i z e d with
longer s e c u l a r trends. Since t h e f i r s t designs a t t h e beginning of t h e l a s t c e n t u r y ,
t h e traction of locomotives increased through improvements in t h e efficiency of
energy conversion and subsequent i n c r e a s e of horsepower, and through increased
weight (only possible because of t h e improvements in t r a c k s and materials). In
terms of total installed horsepower of all locomotives, t h e absolute peak was
achieved in 1929 with more than 100 million horsepower of about 60,000 (mostly
FRACTION IF1
Figure 2.12 Substitution of Steam b y Diesel Locomotives, US.
steam) locomotives. This peak coincides with t h e maximal length of main t r a c k s a l s o
achieved in 1929. Although t h e t o t a l installed h o r s e p o w e r d e c r e a s e d a f t e r 1929, t h e
a v e r a g e t r a c t i v e e f f o r t of all locomotives continued to i n c r e a s e t h r o u g h t h e 1 9 7 0 s
b e c a u s e t h e t o t a l number of locomotives also declined s i n c e 1925.
A number of o t h e r i n d i c a t o r s of t h e r a i l r o a d system in t h e United States show
t h a t t h e 1920s r e p r e s e n t e d t h e culmination of railways. While t h e c a p a c i t y
continued t o i n c r e a s e in a n analogous way to t h e t r a c t i v e e f f o r t of locomotives, t h e
number of p a s s e n g e r - t r a i n c a r s in s e r v i c e p e a k e d in 1924 at more t h a n 57,000 a n d
f r e i g h t - t r a i n c a r s in s e r v i c e peaked in 1925 at more t h a n 2.4 million. The number of
p a s s e n g e r s c a r r i e d a n d passenger-miles also peaked during t h e same d e c a d e
( p a s s e n g e r s a t o v e r 1.2 billion a n d passenger-miles at more t h a n 4 7 billion both in
1920). All of t h e s e i n d i c a t o r s declined subsequently to somewhere between 3 0 a n d
40 p e r c e n t of t h e maximal values r e a c h e d during t h e 1920s.
A c e r t a i n p a r a l l e l in t h e development of r a i l r o a d s a n d automobiles c a n b e
d e t e c t e d . In a more s u p e r f i c i a l way both systems imitated t h e design of t h e
t r a n s p o r t modes t h a t t h e y were competing with and eventually substituted. F i r s t
motor vehicles were l i t e r a l l y horseLess c a r r i a g e s : t h e y were almost identical
e x c e p t f o r t h e d i f f e r e n c e in t h e prime mover. Analogously, e a r l y r a i l r o a d
p a s s e n g e r c a r s were identical to s t a g e c o a c h e s both in design a n d a p p e a r a n c e . More
fundamentally, in t h e United S t a t e s t h e expansion of main t r a c k w a s only slightly
f a s t e r t h a n t h e expansion of s u r f a c e d r o a d s . Both growth p r o c e s s e s a r e
c h a r a c t e r i z e d with a At of r o u g h l y 5 0 y e a r s (i.e. r a i l r o a d s of a b o u t 47 a n d r o a d s
a b o u t 55), but a r e s e p a r a t e d in time by a b o u t 5 0 y e a r s . The inflection points of t h e
t w o growth pulses a r e s e p a r a t e d by 5 6 y e a r s ; t h e main t r a c k s r e a c h e d half t h e
s a t u r a t i o n level in 1890 and s u r f a c e d r o a d s in 1946. Thus, t h e growth of t h e s e two
i n f r a s t r u c t u r e s is c h a r a c t e r i z e d by a "time constant" of a b o u t 5 0 y e a r s , while t h e
decline of r a i l r o a d i n f r a s t r u c t u r e a p p e a r s to b e a slower p r o c e s s . Another
fundamental similarity in t h e evolution of t h e two t r a n s p o r t a t i o n systems i s t h a t
important changes in r o a d t r a n s p o r t o c c u r r e d during t h e y e a r s when most
p e r f o r m a n c e indicators of railways were s a t u r a t i n g . Railways s a t u r a t e d during t h e
1920s and during t h e same d e c a d e t h e substitution of h o r s e s b y automobiles w a s
completed. O t h e r fundamental innovations were a l s o i n t r o d u c e d in t h e r a p i d l y
expanding automotive i n d u s t r y during t h i s p e r i o d s u c h as mass production a n d
closed car bodies. Thus, while t h e r a i l r o a d s were s a t u r a t i n g , t h e automobile
industry matured a n d introduced important c h a n g e s t h a t g e n e r a t e d subsequent
growth.
Tt i s useful t h e r e f o r e to distinguish t w o d i f f e r e n t a s p e c t s in t h e evolution of t h e
t w o t r a n s p o r t i n f r a s t r u c t u r e s . While t h e growth of main t r a c k s a n d s u r f a c e d r o a d s
l a s t e d on t h e o r d e r of 5 0 y e a r s , t h e technological c h a n g e s a n d slibstitution of old b y
new equipment i s a much f a s t e r p r o c e s s of a b o u t 1 0 to 20 y e a r s at t h e level of
locomotive or automotive fleets. These p r o c e s s e s continue e v e n a f t e r t h e s a t u r a t i o n
p h a s e i s r e a c h e d as t h e substitution of steam b y diesel locomotives indicated. Thus,
technological changes are important in both growing and declining industries. Tn
growing industries new technologies are introduced t h r o u g h new additions a n d
replacement, while in t h e declining i n d u s t r i e s new technologies are introduced
exclusively t h r o u g h p a r t i a l replacement of old technologies.
2.4 Canals
I t a p p e a r s t h a t t h e evolution of r a i l a n d r o a d t r a n s p o r t systems p o r t r a y s
similar f e a t u r e s and time c o n s t a n t s ( A t ) in t h e i r p e r f o r m a n c e improvement,
technological snbstitution, a n d i n t h e i n c r e a s e in t h e size of t h e i r s u p p o r t i n g
i n f r a s t r u c t u r e s . The important e v e n t s in t h e evolution of t h e t w o systems, however,
a r e displaced in time b y a b o u t 5 0 y e a r s . Railroads s a t u r a t e d during t h e 1920s when
some of t h e most important technological changes and improvements in r o a d
t r a n s p o r t were initiated. Thus, t h i s similarity i s p e r h a p s indicative of a n i n v a r i a n c e
in t h e development p a t t e r n of t r a n s p o r t systems a n d t h e i r underlying
i n f r a s t r u c t u r e s . A s e r i o u s problem a r i s e s , however, when comparing t h e s e t w o
t r a n s p o r t a t i o n modes with t h o s e t h a t d o not depend exclusively o n t h e rigid, manmade links between them. Airways and waterways a r e examples of t r a n s p o r t systems
t h a t r e l y l e s s on t h e man-made links between t h e nodes b e c a u s e t h e y u s e t h e n a t u r a l
environment (i.e. a i r , r i v e r s a n d c o a s t a l waters) b u t n e v e r t h e l e s s r e q u i r e a n
e l a b o r a t e i n f r a s t r u c t u r e such as a i r p o r t s , h a r b o r s and canals. Consequently, i t is
difficult to a s s e s s t h e t o t a l length of t h e implicit a i r a n d waterway r o u t e s t h a t would
b e equivalent to t h e length of main r a i l r o a d t r a c k s o r s u r f a c e d r o a d s . In both
c a s e s , however, t h e r e are a b s t r a c t c o n c e p t s t h a t would, in principle, c o r r e s p o n d to
t h e length of t h e grid: t h e network of c e r t i f i e d r o u t e c a r r i e r s o r f e d e r a l airways in
a i r t r a n s p o r t , and t h e t o t a l length of continental l ~ a t e r w a y s and c a n a l s .
Unfortunately, t h e annual i n c r e a s e in a c t u a l o p e r a t e d mileage length of a l l a i r
c a r r i e r r o u t e s and t h e mileage of used continental waterways and c a n a l s is not v e r y
a c c u r a t e l y documented in h i s t o r i c a l r e c o r d s . Thus, h e r e w e c a n r e l y only on s p a r s e
a c c o u n t s and p r o b a b l y i n a c c u r a t e estimates.
The f i r s t d e c a d e s of t h e 1 9 t h c e n t u r y in t h e United S t a t e s m a r k e d t h e beginning
of l a r g e r o a d s , canals, tramways a n d l a t e r railway c o n s t r u c t i o n p r o j e c t s . The y e a r s
from a b o u t 1 8 0 0 to 1 8 3 0 h a v e b e e n called t h e "turnpike era" b e c a u s e during t h i s
p e r i o d a number of t h e r o a d s designed f o r t r a v e l between t h e l a r g e r towns o r to t h e
w e s t a c r o s s t h e mountains were completed. Turnpikes, however, were a l r e a d y being
abandoned during t h e 1 8 2 0 s b e c a u s e of a l a c k of financial s u c c e s s ( s e e Taylor,
1962). During t h e same p e r i o d a t t e n t i o n w a s given to c a n a l c o n s t r u c t i o n in a n
a t t e m p t t o develop a more e f f e c t i v e means of i n t e r n a l t r a n s p o r t a t i o n t o complement
c o a s t a l m e r c h a n t t r a n s p o r t . t o c a n a l c o n s t r u c t i o n while t h e construction of
t u r n p i k e s declined. The "canal era" l a s t e d until t h e railways became t h e main mode
of long-distance t r a n s p o r t a few d e c a d e s l a t e r . From t h i s point of view, t h e 1 8 3 0 s
were v e r y t u r b u l e n t y e a r s : many t u r n p i k e s were abandoned, c a n a l c o n s t r u c t i o n w a s
r e a c h i n g i t s p e a k , a n d some e a r l y railway p r o j e c t s were a l r e a d y completed. Thus,
s i n c e t h e 1830s t h e r e h a v e b e e n at l e a s t t h r e e d i f f e r e n t t r a n s p o r t modes t h a t t o
some e x t e n t provided complementary s e r v i c e s b u t w e r e a l s o competing d i r e c t l y in
many m a r k e t segments. In c o n t r a s t t o t u r n p i k e s and railways, c a n a l s connected t h e
v a r i o u s n a t u r a l links of t h e inland waterway system a n d did not r e p r e s e n t a
t r a n s p o r t i n f r a s t r u c t u r e in themselves. Instead, t h e y are r a t h e r c o m p a r a b l e t o
b r i d g e s a n d tunnels as t h e connecting links of r o a d o r r a i l t r a n s p o r t networks.
Thus, c a n a l s made t h e inland waterways into a n i n t e g r a t e d t r a n s p o r t system b y
connecting t h e l a k e s in t h e n o r t h with t h e r i v e r s in t h e south-east a n d mid-west.
However, t h e g r e a t waterway a c r o s s t h e United States n e v e r materialized.
The f i r s t c a n a l s were built during t h e 1780s a n d t h e Richmond Falls was t h e
f i r s t c a n a l t o e x c e e d a length of 7 miles when completed in 1793. From t h e n on t h e
p a c e of c a n a l c o n s t r u c t i o n a c c e l e r a t e d : b y 1 8 0 0 t h e t o t a l length of c a n a l s e x c e e d d
5 0 miles and by 1 8 2 5 more t h a n 1 , 0 0 0 miles w e r e in o p e r a t i o n . Rapid c o n s t r u c t i o n
continued f o r a n o t h e r 20 y e a r s o r s o , r e a c h i n g 3.600 miles in 1850 a n d leveling off
at a b o u t 4,000 miles 20 y e a r s l a t e r . T h e r e a f t e r t h e c a n a l business was s o s e r i o u s l y
e r o d e d b y competition from t h e r a i l r o a d s t h a t many important c a n a l s were
decommissioned. Subsequently, t h e length of a l l c a n a l s in use p r o c e e d e d t o decline.
In t h e United S t a t e s , t h e r i s e and fall of o p e r a t e d c a n a l s p a r a l l e l s t h e growth a n d
decline of t h e main railway t r a c k s but i s displaced in time b y a b o u t 5 0 y e a r s . In
both c a s e s t h e growth in mileage of t h e o p e r a t e d i n f r a s t r u c t u r e i n c r e a s e d r a p i d l y ,
but a f t e r s a t u r a t i o n t h e decline w a s l e s s r a p i d b y f a r .
Figure 2.13 shows t h e i n c r e a s e in t h e length of c a n a l s in t h e United States as a
logistic growth pulse with a s a t u r a t i o n level of a b o u t 4,000 miles a f t e r t h e 1860s.
The inflection point, o r t h e maximum rate of growth, w a s r e a c h e d i n 1835 a n d t h e At
i s a b o u t 3 0 y e a r s . Thus, c a n a l s h a v e a time c o n s t a n t c o m p a r a b l e t o t h a t of t h e
airways but s h o r t e r t h a n railways and r o a d s . A possible explanation f o r t h i s
d i f f e r e n c e i s t h a t both c a n a l s a n d airways r e p r e s e n t only o n e important component
of t h e i r a c t u a l i n f r a s t r u c t u r e s , which f o r t h e f o r m e r includes all waterways in
addition t o some man-made c a n a l s , a n d f o r t h e latter a l a r g e i n f r a s t r u c t u r e of
s u p p o r t i n g systems. On t h e o t h e r hand, r a i l r o a d s and s u r f a c e d r o a d s in themselves
c o n s t i t u t e a l a r g e c o n n e c t e d i n f r a s t r u c t u r e t h a t i s essentially a l l built f o r a
s p e c i f i c p u r p o s e , w h e r e a s t o a l a r g e e x t e n t t h e w a t e r a n d airways utilize t h e
n a t u r a l environment with additional s u p p o r t i n g i n f r a s t r u c t u r e s . Thus, t h i s r e s u l t
may simply i l l u s t r a t e t h a t i t t a k e s l o n g e r t o c o n s t r u c t l a r g e i n f r a s t r u c t u r e s s u c h as
r o a d s a n d t r a c k s compared with c o n s t r u c t i n g s e l e c t e d links (canals o r more
a b s t r a c t l y a i r c o r r i d o r s ) a n d nodes ( a i r p o r t s and h a r b o r s ) in o r d e r t o e x p a n d a new
t r a n s p o r t system such as water a n d airways into a n a l r e a d y available n a t u r a l
environment.
XK
Fraction F = -
Figure 2.13 Length of Canals, US.
2.5 Transport Infrastructures
The d i f f e r e n c e in t h e time c o n s t a n t s between a i r a n d inland w a t e r t r a n s p o r t
systems on t h e o n e hand a n d r a i l and r o a d t r a n s p o r t on t h e o t h e r , indicate t h a t at
l e a s t at t h i s level of comparison t h o s e t r a n s p o r t systems with more e x t e n s i v e
i n f r a s t r u c t u r a l r e q u i r e m e n t s may t a k e l o n g e r to e x p a n d a n d , possibly, to complete
t h e whole life c y c l e from growth t o s a t u r a t i o n a n d l a t e r s e n e s c e n c e . In o r d e r to
assess w h e t h e r t h e time c o n s t a n t s a r e r e a l l y d i f f e r e n t , Figure 2.14 shows t h e
substitution of d i f f e r e n t t r a n s p o r t systems during t h e last 180 y e a r s in t h e United
S t a t e s in t e r m s of t h e o p e r a t e d mileage of t h e competing i n f r a s t r u c t u r e s - c a n a l s ,
main railway t r a c k s , s u r f a c e d r o a d s and f e d e r a l airway r o u t e miles. Thus, t h e
growth of t h e t r a n s p o r t networks i s s e e n h e r e as t h e competition p r o c e s s of t h e
f o u r t r a n s p o r t modes in t e r m s of t h e t o t a l length of o p e r a t e d mileage. S e e n from
t h i s p e r s p e c t i v e t h e substitution of t h e f o u r systems o v e r time a p p e a r s as a r e g u l a r
process.
A number of i n v a r i a n t f e a t u r e s a r e i n h e r e n t in t h i s substitution p r o c e s s .
4 In dealing w i t h more t h e n t w o competing technologies, we must generalize t h e F i s h e r and Pry
FRRCTION [ F I
0.99
Figure 2.14 Substitution of T r a n s p o r t I n f r a s t r u c t u r e s , US.
A t any give time, t h e r e a r e at l e a s t t h r e e important t r a n s p o r t i n f r a s t r u c t u r e s
competing i n t e r m s of s h a r e s of t h e t o t a l r o u t e length of all t r a n s p o r t modes. The
longest t r a n s p o r t i n f r a s t r u c t u r e i s always l o n g e r t h a n at l e a s t half t h e total length.
Consequently, t h e s e c o n d a n d t h i r d longest t r a n s p o r t i n f r a s t r u c t u r e s sum to l e s s
than half of t h e total length. This symmetry a n d dominating r o l e of t h e longest
i n f r a s t r u c t u r e h a s b e e n complemented by a n o t h e r r e g u l a r f e a t u r e during t h e last
1 8 0 y e a r s . The time c o n s t a n t ( A t ) i n c r e a s e s from l e s s t h a n 5 0 y e a r s f o r t h e growth
of railway t r a c k s h a r e s to almost 90 y e a r s f o r s u r f a c e d r o a d s a n d more t h a n 1 3 0
y e a r s f o r airway r o u t e s as s h a r e s of t o t a l length. The time c o n s t a n t i n c r e a s e d b y
a b o u t 40 y e a r s f o r s u c c e s s i v e i n f r a s t r u c t u r e s . The d i s t a n c e among t h e s a t u r a t i o n
p e r i o d s (time of maximal m a r k e t s h a r e s ) of r a i l t r a c k s and s u r f a c e d r o a d s i s a b o u t
100 years.
model, s i n c e i n s u c h c a s e s l o g i s t i c s u b s t i t u t i o n c a n n o t b e p r e s e r v e d i n a l l p h a s e s o f t h e
s u b s t i t u t i o n process. E v e r y c o m p e t i t o r undergoes t h r e e d i s t i n c t s u b s t i t u t i o n phases: growth,
s a t u r a t i o n and decline. T h i s i s i l l u s t r a t e d b y t h e s u b s t i t u t i o n p a t h o f r a i l t r a c k s , which c u r v e s
t h r o u g h a m a x i m u m f r o m i n c r e a s i n g t o d e c l i n i n g m a r k e t s h a r e s ( s e e F i g u r e 2.14). I n t h e m o d e l o f
t h e s u b s t i t u t i o n p r o c e s s , w e a s s u m e t h a t o n l y o n e c o m p e t i t o r is i n t h e s a t u r a t i o n p h a s e a t a n y
given time, t h a t declining technologies f a d e a w a y s t e a d i l y a t l o g i s t i c r a t e s and t h a t new
competitors e n t e r t h e m a r k e t and grow a t l o g i s t i c r a t e s . As a r e s u l t , t h e s a t u r a t i n g technology
i s l e f t w i t h t h e r e s i d u a l m a r k e t s h a r e s (i.e., t h e d i f f e r e n c e b e t w e e n 1 a n d t h e s u m o f f r a c t i o n a l
m a r k e t s h a r e s o f a l l o t h e r c o m p e t i t o r s ) a n d is f o r c e d t o f o l l o w a n o n l o g i s t i c p a t h t h a t J o i n s i t s
period of g r o w t h t o I t s s u b s e q u e n t period of decline. A f t e r t h e c u r r e n t , s a t u r a t i n g c o m p e t i t o r
h a s r e a c h e d a l o g i s t i c r a t e o f d e c l i n e , t h e n e x t o l d e s t c o m p e t i t o r e n t e r s its s a t u r a t i o n p h a s e a n d
t h e p r o c e s s i s r e p e a t e d u n t i l all b u t t h e m o s t r e c e n t c o m p e t i t o r a r e i n decline. A m o r e
c o m p r e h e n s i v e d e s c r i p t i o n o f t h e m o d e l a n d a s s u m p t i o n s i s g i v e n i n N a k i c e n o v i c (1979).
This r e s u l t may a p p e a r t o c o n t r a d i c t o u r e a r l i e r o b s e r v a t i o n t h a t t h e t o t a l
length of r a i l t r a c k s and s u r f a c e d r o a d s took longer t o c o n s t r u c t t h a n w a t e r and
airways. In f a c t , t h e substitution dynamics of i n f r a s t r u c t u r e lengths o f f e r s a
surprisingly consistent time t a b l e compared with t h e duration of growth pulses of
t h e f o u r t r a n s p o r t modes during t h e p a s t 180 y e a r s . The a p p a r e n t inconsistency i s
due t o t h e d i f f e r e n t ways of measuring t h e growth rates and l i f e c y c l e s of t h e
r e s p e c t i v e i n f r a s t r u c t u r e s . In t h e c a s e of m a r k e t s h a r e s w e are analyzing t h e
i n c r e a s e of a p a r t i c u l a r t r a n s p o r t i n f r a s t r u c t u r e in t e r m s of t h e length of a l l
networks t o g e t h e r . Thus, even t h e v e r y r a p i d growth rate of airway r o u t e mileage
i s t r a n s l a t e d into a comparatively long time constant b e c a u s e at t h e same time t h e
total length of a l l t r a n s p o r t networks i s a l s o growing rapidly. Due t o t h e s e r a p i d
growth rates, t h e s h a r e of s u r f a c e d r o a d s h a s been declining s i n c e t h e 1970s
whereas t h e total length of s u r f a c e d r o a d s i s still growing toward t h e s a t u r a t i o n
level (see ).
Thus, t h e total length of t r a n s p o r t i n f r a s t r u c t u r e c a n s t i l l b e growing a n d e v e n
b e decades away from ultimate s a t u r a t i o n and final s e n e s c e n c e while t h e s h a r e s of
i t s length in t h e length of a l l t r a n s p o r t i n f r a s t r u c t u r e s are declining. This w a s t h e
case with canals, r a i l r o a d s and s u r f a c e d r o a d s . Thus, t h e s a t u r a t i o n a n d decline of
market s h a r e s p r e c e d e s s a t u r a t i o n in absolute growth in a n increasing market. This
i s s o b y definition, but i t means t h a t t h e eventual s a t u r a t i o n of a n y competing
technology c a n b e anticipated in t e r m s of t h e substitution dynamics in a growing
market. The logistic growth p h a s e of r a i l t r a c k s s p a n s t h e p e r i o d from 1840 t o s a y
1916 (see Figure 2.11) with s a t u r a t i o n in t h e 1920s and s e n e s c e n c e t h e r e a f t e r . The
dominance of r a i l t r a c k s in terms of m a r k e t s h a r e s a l s o lasted form 1840 t o 1915. In
t h i s p a r t i c u l a r c a s e t h i s means t h a t t h e beginning of t h e growth pulse coincides with
t h e beginning of market dominance and t h a t s a t u r a t i o n immediately follows t h e .loss
of m a r k e t dominance. The s a t u r a t i o n in m a r k e t s h a r e s , however, o c c u r r e d in t h e
1870s, indicating t h a t s a t u r a t i o n in t h e growth pulse must o c c u r , although i t w a s
more than f o u r decades away.
Although t h e substitution of o l d e r by younger t r a n s p o r t a t i o n modes w a s a
r e g u l a r p r o c e s s when measured in terms of total mileage of t h e f o u r t r a n s p o r t
i n f r a s t r u c t u r e s , i t i s n e v e r t h e l e s s only a p r o x y f o r t h e r e a l dynamics of
t r a n s p o r t a t i o n systems, which should b e measured in some common p e r f o r m a n c e
unit. However, since t r a n s p o r t systems provide a whole r a n g e of s e r v i c e s , i t i s
difficult t o define such a common d e s c r i p t o r . Two obvious c h o i c e s would b e t o use
ton o r p e r s o n kilometers p e r y e a r as a common unit. N e v e r t h e l e s s , t h i s i s still
i n a p p r o p r i a t e s i n c e such a common unit does not distinguish between f r e i g h t a n d
p a s s e n g e r t r a n s p o r t o r between s h o r t and long-distances. Thus, t h e r e i s n o obvious
short-cut and i t a p p e a r s n e c e s s a r y t o analyze both p a s s e n g e r and f r e i g h t
s e p a r a t e l y f o r both s h o r t a n d long distances (e.g. i n t r a a n d i n t e r c i t y t r a v e l ) .
Fortunately, historical d a t a a r e available t h a t make i t possible t o r e c o n s t r u c t t h e
dynamics of t h e s e substitution p r o c e s s e s f o r at l e a s t some countries. F o r example,
Figure 2.15 shows t h e substitution of d i f f e r e n t t r a n s p o r t a t i o n modes in i n t e r c i t y
(long-distance) p a s s e n g e r t r a v e l in t h e United States s i n c e 1950.
By excluding u r b a n a n d metropolitan t r a n s p o r t b e c a u s e explicit s t a t i s t i c s are
generally lacking, t h e competition f o r i n t e r c i t y p a s s e n g e r t r a f f i c i s r e d u c e d t o f o u r
significant t r a n s p o r t modes. Figure 2.15 shows t h e substitution of railways, busses,
cars and airways as competing t r a n s p o r t a t i o n systems f o r long-distance t r a v e l . The
s h a r e s of e a c h mode of t r a n s p o r t a r e calculated in t e r m s of passenger-miles
t r a v e l e d in a given y e a r . According t o t h e market substitution analysis in Figure
2.15, t h e automobile i s still t h e main choice f o r t h e majority of Americans and will
F/I 1-FI
FRACTION IF1
Figure 2.15 I n t e r c i t y P a s s e n g e r T r a f f i c Substitution, US.
remain dominantly s o well into t h e n e x t c e n t u r y in s p i t e of t h e m a r k e t s h a r e
i n c r e a s e s gained by a i r t r a v e l . The l o s e r s are t h e railways and busses. The
substitution dynamics indicate t h a t during t h e n e x t two d e c a d e s t h i s t r e n d will
expand t h e s h a r e of a i r w a y s in i n t e r c i t y t r a v e l t o almost 40 p e r c e n t , r e d u c e t h e
s h a r e of automobiles t o l i t t l e more t h a n 60 p e r c e n t , a n d virtually eliminate railways
a n d busses. Thus, automobiles will remain t h e most important, although declining,
form of long-distance t r a v e l t h r o u g h o u t t h i s c e n t u r y in t h e United S t a t e s , while
a i r c r a f t will continue t h e i r r a p i d expansion by increasing t h e m a r k e t s h a r e s t h e y
currently control.
Unfortunately, F i g u r e 2.15 d o e s not indicate t h e full drama of t h i s r e p l a c e m e n t
p r o c e s s b e c a u s e d a t a are not available f o r t h e p e r i o d b e f o r e 1950. N e v e r t h e l e s s ,
t h e substitution p r o c e s s i s consistent with t h e mileage substitution of t h e r e s p e c t i v e
t r a n s p o r t a t i o n i n f r a s t r u c t u r e s from Figure 2.14. For example, t h e s h a r e of main
railway t r a c k s d e c r e a s e s down to l e s s t h a n a o n e - p e r c e n t s h a r e b y t h e end of t h e
c e n t u r y , a n d t h e s h a r e of railways in i n t e r c i t y t r a v e l phases-out e v e n e a r l i e r
during t h e 1970s. During t h e same d e c a d e t h e s h a r e s of both automobiles in
i n t e r c i t y t r a v e l and of s u r f a c e d r o a d mileage a r e s a t u r a t i n g . In b o t h c a s e s t h e
s h a r e s of airways are increasing and are e x p e c t e d t o r e a c h a position of dominance
(with c o n t r o l of more t h a n half t h e "market") during t h e f i r s t d e c a d e s of t h e n e x t
century.
A l l of t h e s e examples h a v e indicated t h a t t h e s t r u c t u r a l c h a n g e s in t r a n s p o r t
systems and t h e i r r e s p e c t i v e i n f r a s t r u c t u r e s t a k e p l a c e o v e r long time periods.
T h e r e is a l s o s t r o n g evidence t h a t some f e a t u r e s of t h e s e c h a n g e s are r a t h e r
invariant in time. E a c h of t h e t r a n s p o r t systems developed (with logistic
improvement of p e r f o r m a n c e a n d i n c r e a s e s in t h e length of t h e i r r e s p e c t i v e
networks), s a t u r a t e d , and t h e n p r o c e e d e d into a p e r i o d of s e n e s c e n c e . E x a c t l y t h e
same p a t t e r n i s r e p e a t e d i n t h e s e c u l a r c h a n g e s of m a r k e t s h a r e s as t h e s e systems
compete with e a c h o t h e r .
The a b o v e i s obviously only a p a r t i a l d e s c r i p t i o n of t h e s e complex systems a n d
t h e r e are c e r t a i n l y many o t h e r , p e r h a p s b e t t e r , ways of d e s c r i b i n g t h e dynamics of
t h e s e systems. The intriguing a s p e c t of t h e logistic d e s c r i p t i o n of t h e development
of t r a n s p o r t a t i o n systems i s t h a t t h e y a p p e a r to b e interwoven with r e g u l a r f e a t u r e s
a n d a p a t t e r n of substitution dynamics o v e r a p e r i o d of a b o u t t w o c e n t u r i e s . In
o r d e r to indicate t h a t t h i s i s n o t a s i n g u l a r f e a t u r e unique to t h e evolution of
t r a n s p o r t a t i o n systems, w e will now show t h a t a similar r e g u l a r i t y e x i s t s in t h e
evolution of e n e r g y systems.
3 PRIMAKY ENERGY
3.1 Energy Consumption
A t t h e beginning of t h e 1 9 t h c e n t u r y , fuel wood, a g r i c u l t u r a l wastes and
mechanical wind and water power supplied most of t h e inanimate e n e r g y in addition
t o animal and human muscle power. This, f o r p r e s e n t s t a n d a r d s , p o o r e n e r g y menu,
a l r e a d y r e p r e s e n t e d a sophisticated e n e r g y system compared t o e a r l i e r p r a c t i c e s .
W e have s e e n t h a t a considerable i n f r a s t r u c t u r e of r o a d s (turnpikes) and canals w a s
in place in t h e 1 9 t h c e n t u r y f o r timber and l a t e r c o a l t r a n s p o r t . Mining,
manufacture and i r r i g a t i o n were a l s o usually associated with e l a b o r a t e systems of
dams and water-wheels. This indicates t h a t in t h e e a r l y industrial development p h a s e
e n e r g y use depended on t h e t r a n s p o r t system, and t h a t e n e r g y w a s one of t h e more
important components of goods t r a n s p o r t e d on c a n a l s , waterways, t u r n p i k e s and
roads.
In primary e n e r g y terms, fuel wood r e p r e s e n t e d most of t h e e n e r g y inputs.
Figure 3 . 1 gives t h e annual consumption of a l l fuel wood, fossil e n e r g y s o u r c e s ,
d i r e c t uses of mechanical water power and h y d r o e l e c t r i c power consumption in t h e
United S t a t e s s i n c e 1800. Data a r e plotted on a logarithmic s c a l e and show t h e
exponential growth p h a s e s in consumption of t h e most important s o u r c e s of p r i m a r y
e n e r g y during t h e l a s t 180 y e a r s by piece-wise l i n e a r s e c u l a r t r e n d s .
In t h e United S t a t e s t h e consumption of fuel wood, o n c e t h e most important
s o u r c e of e n e r g y , h a s declined s i n c e t h e beginning of t h e c e n t u r y , although i t s use
i s still widespread, especially in t h e developing p a r t s of t h e world. With t h e
expansion of r a i l r o a d s , t h e s t e e l industry a n d t h e application of steam in g e n e r a l ,
coal use i n c r e a s e d exponentially until t h e 1910s a n d h a s oscillated e v e r since. Both
oil and n a t u r a l g a s were introduced during t h e 1870s and t h e i r consumption h a s
i n c r e a s e d with even more r a p i d exponential growth r a t e s e v e r since. In f a c t , oil
and n a t u r a l g a s c u r v e s h a v e t h e same s h a p e a n d almost identical growth r a t e s ; t h e y
a r e just shifted in time by about 1 0 t o 15 y e a r s . The use of oil and n a t u r a l g a s grew
in parallel with the petrochemical industry, e l e c t r i c i t y a n d e l e c t r i c a l industry,
i n t e r n a l combustion and e l e c t r i c prime movers. Nuclear e n e r g y i s still in i t s e a r l y
phase of development, t h e r e f o r e t h e s t e e p growth prevailing o v e r t h e l a s t d e c a d e
may not b e indicative of i t s f u t u r e r o l e . During t h e l a s t y e a r s , however, t h e growth
of nuclear e n e r g y in t h e United S t a t e s a n d worldwide h a s declined t o more moderate
rates.
-
-
Figure 3.1
-
-
P r i m a r y E n e r g y Consumption, U.S.
3.2 Energy Substitution
Thus, during t h i s p e r i o d of almost two c e n t u r i e s , e n e r g y consumption did n o t
d r a w equally from all s o u r c e s , n o r did t h e use of a l l e n e r g y s o u r c e s i n c r e a s e
equally. Yet, p r i m a r y e n e r g y consumption (including fuel wood) i n c r e a s e d
exponentially at a n a v e r a g e growth rate of a b o u t t h r e e p e r c e n t p e r y e a r . The
decline of o l d e r e n e r g y s o u r c e s was more t h a n compensated f o r b y t h e r a p i d growth
of t h e new ones. Thus, i t i s evident t h a t t h e o l d e r forms of e n e r g y h a v e b e e n
substituted by t h e newer ones. Figure 3.2 shows p r i m a r y e n e r g y substitution in t h e
United S t a t e s . 5
Figure 3 . 2
P r i m a r y E n e r g y Substitution, US.
Mechanical w a t e r power (mostly h y d r o and some wind mills) and h y d r o e l e c t r i c
power a r e not o b s e r v a b l e in t h e f i g u r e d u e t o t h e i r low contribution t o t o t a l e n e r g y
supply: t h e y b a r e l y e x c e e d e d t h e one-percent level during v e r y s h o r t p e r i o d s and
are otherwise u n d e r t h a t c r i t i c a l level. Thus, b e f o r e t h e 1820s fuel wood provided
f o r virtually a l l t h e e n e r g y needs of t h e United States. Coal e n t e r e d t h e competition
p r o c e s s in 1817 at t h e o n e - p e r c e n t level a n d up t o t h e 1880s i t w a s essentially a two
w h a t e v e r gains c o a l made were t r a n s l a t e d i n t o losses f o r fuel
technology m a r k e t
wood.
-
N e v e r t h e l e s s , wood remained a n important c o n s t r u c t i o n material and s o u r c e of
h e a t and power well i n t o t h e l a s t d e c a d e s of t h e 1 9 t h c e n t u r y s o t h a t t h e steam a g e
began in a n economy based on wood use. The f i r s t steam-boats and locomotives w e r e
f i r e d with wood, which remained t h e principal fuel used by r a i l r o a d s until a b o u t
1870 ( S h u r r and N a t s c h e r t , 1960). The i r o n i n d u s t r y was a n o t h e r l a r g e wood
consumer. Around 1850, more t h a n half of a l l t h e i r o n produced w a s s t i l l smelted
5 T h e f r a c t i o n a l s h a r e s (f) a r e n o t p l o t t e d d i r e c t l y b u t a s t h e l i n e a r t r a n s f o r m a t i o n o f t h e l o g i s t i c
c u r v e , i.e. f/(l-f)- a s t h e r a t i o o f t h e m a r k e t , s h a r e t.eken b y a e l v a n e n e r g y s o u r c e o v e r t h e s u m
of t h e m a r k e t s h a r e s of all o t h e r competing e n e r g y s o u r c e s . T h i s f o r m of p r e s e n t a t i o n r e v e a l s
t h e logistic substitution path a s an almost linear secular trend with small annual perturbations.
T h u s , t h e p r e s e n c e o f s o m e l i n e a r t r e n d s i n F i g u r e 3.2 i n d i c a t e s w h e r e t h e f r a c t i o n a l s u b s t i t u t i o n
of e n e r g y s o u r c e s follows a l o g i s t i c curve.
with c h a r c o a l . In s p i t e of t h e s e l a r g e uses of wood, t h e total amount consumed in
manufacturing and t r a n s p o r t a t i o n was small compared to t h e huge quantities used in
households. By 1880, t h e industrial use of wood declined so t h a t domestic u s e
accounted f o r more t h a n 9 6 p e r c e n t of fuel wood consumed ( S c h u r r and N a t s c h e r t ,
1960). A t t h e same time, c o a l a l r e a d y supplied almost one-half of all e n e r g y needs,
most of i t being used by emerging industries. In 1880, c o a l supplied almost 9 0
p e r c e n t of t h e fuel used f o r smelting iron. Thus, in t h i s r e s p e c t , t h e end of t h e l a s t
c e n t u r y marks t h e beginning of t h e industrial development p e r i o d in t h e United
States.
The f i r s t use of c r u d e oil and n a t u r a l g a s in t h e United States d a t e s back to t h e
beginning of t h e 1 9 t h c e n t u r y and both r e a c h e d t h e o n e - p e r c e n t m a r k e t s h a r e
during t h e 1880s. From t h e n o n t h e use of c r u d e oil expanded somewhat f a s t e r as
time p r o g r e s s e d and by 1950 c r u d e oil consumption s u r p a s s e d t h a t of coal. The use
of n a t u r a l g a s s u r p a s s e d c o a l nine y e a r s l a t e r . I t should b e noted t h a t even as l a t e
as t h e 1920s t h e use of c r u d e oil w a s not much l a r g e r t h a n t h e consumption of f u e l
wood. When compared with e a r l i e r p e r i o d s , i t i s r e m a r k a b l e t h a t t h e s t r u c t u r e of
e n e r g y consumption changed more during t h e p e r i o d of oil dominance.
The 1950s, when oil became t h e dominant s o u r c e of e n e r g y , r e p r e s e n t t h e
beginning of more intense competition between various e n e r g y s o u r c e s both in t h e
United S t a t e s and in t h e world. During 1 5 0 y e a r s t h e e n e r g y s o u r c e t h a t dominated
t h e e n e r g y supply at t h e same time a l s o c o n t r i b u t e d more t h a n one-half of a l l
p r i m a r y e n e r g y consumption - from 1800 to 1880 fuel wood and from 1880 t o 1950
coal. This i s similar to t h e dominance of o n e t r a n s p o r t i n f r a s t r u c t u r e with more
t h a n half of a l l mileage o b s e r v e d in t h e substitution of c a n a l s , r a i l t r a c k s , s u r f a c e d
r o a d s a n d airways. During t h e 1970s, c r u d e oil w a s close t o achieving a 50-percent
s h a r e , b u t b e f o r e a c t u a l l y surpassing t h i s mark p r o c e e d e d t o decline. Thus, during
t h e l a s t t h r e e d e c a d e s t h r e e important s o u r c e s of e n e r g y s h a r e d t h e m a r k e t without
a single s o u r c e having a pronounced dominance, which i s c o n t r a r y t o t h e p a t t e r n
o b s e r v e d during e a r l i e r p e r i o d s and t h e substitution of t r a n s p o r t i n f r a s t r u c t u r e s .
Figure 3.2 shows n a t u r a l g a s as t h e dominanting e n e r g y s o u r c e a f t e r t h e 1980s,
although c r u d e oil still maintains a b o u t a 3 0 p e r c e n t m a r k e t s h a r e b y t h e end of t h e
c e n t u r y . The f u t u r e potential competitors of n a t u r a l g a s , s u c h a s n u c l e a r o r s o l a r
e n e r g y , h a v e not y e t c a p t u r e d sufficient m a r k e t s h a r e s t o allow estimation of t h e i r
f u t u r e p e n e t r a t i o n r a t e s . The s t a r t i n g point f o r m a r k e t p e n e t r a t i o n of n u c l e a r
e n e r g y c a n b e d a t e d b a c k to t h e 1960s when n u c l e a r power a c q u i r e d slightly l e s s
t h a n a one-percent s h a r e in p r i m a r y e n e r g y . Allowing f o r f u r t h e r cancellations of
a l r e a d y o r d e r e d power p l a n t s a n d possible decommission of t h o s e in o p e r a t i o n and
c o n s t r u c t i o n , we h a v e assumed t h a t n u c l e a r e n e r g y could at most double i t s c u r r e n t
m a r k e t s h a r e t o a b o u t f o u r p e r c e n t b y t h e y e a r 2000 and h a v e used t h i s assumed
p e n e t r a t i o n r a t e f o r t h e p r o j e c t i o n in Figure 3.2. This l e a v e s n a t u r a l g a s with t h e
lion's s h a r e in p r i m a r y e n e r g y advancing i t s position t o t h e dominant e n e r g y s o u r c e
a f t e r this c e n t u r y .
Thus, a prominent f e a t u r e of t h e projection of p r i m a r y e n e r g y substitution
dynamics i n t o t h e f u t u r e i s t h e emergence of n a t u r a l g a s as t h e dominant e n e r g y
s o u r c e during t h e n e x t d e c a d e s . According t o 1 . more t h a n half of a l l t h e p r i m a r y
e n e r g y consumed during t h e f i r s t d e c a d e s of t h e n e x t c e n t u r y will b e n a t u r a l g a s .
This r e s u l t i l l u s t r a t e s not only t h a t t h e n a t u r a l g a s bubble will b c a b s o r b e d in a few
y e a r s , b u t a l s o t h a t methane technologies will develop in t h e f u t u r e c r e a t i n g new
growth s e c t o r s .
Although, this r e s u l t i s unexpected in t e r m s of t h e numerous e n e r g y d e b a t e s of
t h e last 1 0 t o 15 y e a r s , i t i s p e r h a p s r e a s s u r i n g t h a t w e may not h a v e t o r e l y on
n u c l e a r o r a l t e r n a t i v e e n e r g y s o u r c e s f o r a n o t h e r 50 y e a r s o r s o a f t e r all. Instead,
t h e possible f u t u r e t h a t emerges would r e q u i r e l e s s r a d i c a l c h a n g e s , but still b e a
challenging t a s k t o develop new technologies and improve t h e p e r f o r m a n c e of those
a l r e a d y employed, such as d e e p drilling, pipelines, a n d methane conversion into
o t h e r e n e r g y c a r r i e r s (e.g., e l e c t r i c i t y a n d methanol). Despite t h e c u r r e n t
difficulties in expanding t h e use of n a t u r a l g a s in a time of worldwide economic
slowdown and low e n e r g y (i.e., c r u d e oil) p r i c e s , o u r s c e n a r i o paints a d i f f e r e n t
p i c t u r e , a l b e i t in t h e long r u n . In o r d e r t o gain a b e t t e r understanding of how such
changes may come about to allow methane t o e m e r g e as t h e dominant e n e r g y s o u r c e
of t h e f u t u r e , w e will f i r s t investigate t h e development of oil and n a t u r a l g a s
production. T h e r e a f t e r w e will briefly r e t u r n t o t h e b r o a d e r p i c t u r e of p r i m a r y
e n e r g y substitution and analyze t h e evolution of e n e r g y t r a n s p o r t i n f r a s t r u c t u r e s .
3.3 Oil and Natural Gas Production
Already t h e g e n e r i c name "oil and gas" indicates t h a t during most of i t s
century-old h i s t o r y n a t u r a l g a s o r methane w a s known as a by-product of oil.
During t h e e a r l y days n a t u r a l g a s was both essential b u t often a nuisance t o t h e oil
p r o d u c e r . Methane p r e s s u r e in a n oil and gas deposit s e r v e d t o pump t h e oil t o t h e
s u r f a c e but i t w a s a nuisance because t h e g a s t h a t actually r e a c h e d t h e s u r f a c e h a d
to b e f l a r e d in o r d e r t o avoid t h e d a n g e r of explosion. Thus, n a t u r a l g a s w a s in f a c t
e x t r a c t e d t o g e t h e r with oil but w a s usually wasted. A t t h e same time c i t y g a s (mostly
methane) w a s being produced from c o a l and oil t o supply premium fuel especially f o r
lighting and domestic uses. I t i s not s u r p r i s i n g t h e r e f o r e t h a t some associated g a s
was soon used f o r consumption.
according t o S c h u r r , et.al. (1960) t h e e a r l i e s t r e c o r d e d commercial use of
n a t u r a l g a s in t h e new world d a t e s back t o 1 8 2 1 ( a t t h e time when c o a l supplied just
one-percent of primary e n e r g y and fuel wood and d r a f t animals t h e r e s t ) , when i t
w a s used as lighting fuel in Fredonia, New York. Natural g a s continued t o b e used
sporadically throughout t h e 19th c e n t u r y . The f i r s t pipeline was c o n s t r u c t e d from
Murrysville t o Pittsburgh (Pennsylvania) in 1883 a f t e r t h e discovery of a l a r g e well
in 1878. Despite such pioneering p r o j e c t s by t h e emerging oil and g a s industry,
methane w a s in g e n e r a l considered a waste product. By 1878, both c r u d e oil a n d
n a t u r a l g a s s u r p a s s e d a one-percent s h a r e in primary e n e r g y consumption b u t most
of t h e n a t u r a l g a s consumed in t h e following d e c a d e s was used in t h e vicinity of t h e
oil fields.
Natural g a s production h a s s i n c e grown rapidly b u t b e c a u s e until t h e last
decades most methane discoveries were r e l a t e d t o t h e s e a r c h f o r oil, n a t u r a l g a s
e x t r a c t i o n w a s mainly associated with oil production. Accurate s t a t i s t i c s of n a t u r a l
g a s production from oil and g a s wells (associated and non-associated g a s ,
respectively) a r e not available f o r t h e p e r i o d b e f o r e 1935. Figure 3 . 3 shows t h e
s t e a d y i n c r e a s e in n a t u r a l g a s production from g a s wells (gas technology). In 1935
about 40 p e r c e n t of t h e methane produced was from oil wells (oil technology) but
Figure 3 . 3 shows t h a t by t h e end of t h e c e n t u r y 90 p e r c e n t of production should b e
d in total
from non-associated deposits. The d e c r e a s i n g s h a r e s of a ~ s o c i a t ~ egas
production i l l u s t r a t e t h e f a c t t h a t t h e n a t u r a l g a s industry i s in t h e p r o c e s s of
decoupling itself from oil. The intimately and i n e x t r i c a b l y r e l a t e d e x t r a c t i o n ,
FRRCT ION IF I
Figure 3.3
N a t u r a l Gas Production from Oil and Gas Wells, US.
t r a n s p o r t , conversion and end-use technologies f o r oil and methane may b e slowly
diverging on increasingly independent p a t h s .
Figure 3.4 shows a r e f i n e d v e r s i o n of t h e p r i m a r y e n e r g y substitution dynamics
form Figure 3.2. This r e s u l t indicates t h a t technological substitution c a n b e
c h a r a c t e r i z e d by v e r y r e g u l a r time c o n s t a n t s provided t h a t t h e h i s t o r i c a l d a t a i s
a c c u r a t e enough to provide t h e information r e q u i r e d f o r f u r t h e r analytical
resolution. This i s to a n e x t e n t possible in t h e c a s e of p r i m a r y e n e r g y consumption
b e c a u s e d i f f e r e n t e n e r g y s o u r c e s c a n b e measured in common (physical, e n e r g y )
units and b e c a u s e t h e i r use i s r e l a t i v e l y well documented in t h e United States f o r
t h e l a s t 1 9 0 y e a r s . Figure 3.4 r e p r e s e n t s such a h i g h e r resolution b e c a u s e
associated n a t u r a l g a s (oil technology from Figure 3.3 i s now r e a l l o c a t e d to t h e use
of c r u d e oil a n d l e a v e s t h e non-associated g a s from g a s wells to "gas technology".
This r e s u l t shows t h a t although a s s o c i a t e d g a s h a s long b e e n a v a i l a b l e as a by
p r o d u c t of oil i t s use d o e s not r e p r e s e n t t h e a c t u a l evolution of g a s technologies.
Figure 3.4 shows t h a t t h i s refinement to t h e substitution p r o c e s s so improves t h e
r e g u l a r i t y t h a t t h e time c o n s t a n t s now c l u s t e r at a b o u t 70 y e a r s f o r a l l e n e r g y
s o u r c e s and t h a t t h e s a t u r a t i o n i n t e r v a l s between c o a l , oil and g a s technologies are
also s e p a r a t e d by a b o u t 50 y e a r s . During t h e s a t u r a t i o n p e r i o d s of t h e dominant
e n e r g y s o u r c e s , new ones a r e introduced. Gas technologies a r e introduced during
t h e s a t u r a t i o n of c o a l , a n d n u c l e a r e n e r g y during t h e s a t n r a t i o n of oil d u e to t h e
addition of associated g a s technologies. The a c t u a l oil s h a r e s now i n c r e a s e d so t h a t
t h e importance of oil during t h e l a s t d e c a d e s i s visible as c l e a r dominance of m o r e
t h a n half of a l l e n e r g y supplies.
Figure 3.4
E n e r g y Substitution and Gas Technologies, U .S.
This r e s u l t i s encouraging s i n c e i t indicates a possible n e x t s t e p in t h e analysis
of t h e technological evolution of t r a n s p o r t systems and i n f r a s t r u c t u r e s . The
division of n a t u r a l g a s into oil and g a s technologies i s equivalent t o assigning some
f e e d e r tramways t o e a r l y r a i l r o a d s and o t h e r t o canal i n f r a s t r u c t u r e in terms of a
common measuring unit and, possibly, assigning f e e d e r r o a d vehicles t o r a i l r o a d s ,
especially t h e r a i l r o a d owned horse-vehicles. An a c c u r a t e analysis of t h e model
s p l i t among t h e d i f f e r e n t models of t r a n s p o r t a t i o n , in t e r m s of at l e a s t one common
p e r f o r m a n c e indicator, i s t h e n e x t n e c e s s a r y and p r o b a b l y v e r y awarding s t e p .
3.4 Oil and Gas Transport
In c o n t r a s t t o oil and g a s , wood w a s primarily consumed locally, close t o t h e
s o u r c e . Some fuel wood w a s t r a n s p o r t e d o v e r l o n g e r d i s t a n c e s mostly by r i v e r
flotation and distributed by waterways o r roads. Coal on t h e o t h e r hand, r e p r e s e n t s
a more c o n c e n t r a t e d form of e n e r g y than fuel wood and coal mines a more
c o n c e n t r a t e d s o u r c e t h a n f o r e s t s (since c o a l h a s a h i g h e r h e a t content p e r unit
weight t h a n wood) s o t h a t i t w a s generally t r a n s p o r t e d o v e r longer distances t h a n
fuel wood. The e x t r e m e c a s e i s t h e modest o v e r s e a s coal t r a n s p o r t , b u t more
usually coal w a s t r a n s p o r t e d (nationwide) by b a r g e s , t r a i n s o r t r u c k s ( e a r l i e r h o r s e
wagons). Thus, t h e s h i f t from a wood t o c o a l economy w a s accompanied by t h e
expansion of e n e r g y t r a n s p o r t o v e r longer distances and t o increasing t r a n s p o r t
modes. The widespread u s e of c r u d e oil b r o u g h t a n o t h e r t r a n s p o r t mode in addition
t o t a n k e r s , t r a i n s and t r u c k s - oil pipelines. Pipelines are becoming a n important
f r e i g h t t r a n s p o r t mode with market s h a r e s in t o t a l ton-kilometers p e r y e a r
comparable t o those of t r a i n and t r u c k t r a n s p o r t . They are a l s o comparable t o
railways in t e r m s of t h e t o t a l length of t h e i n f r a s t r u c t u r e o r grid: t h e t o t a l length
of main t r a c k in t h e United S t a t e s i s , about 200,000 miles, slightly s h o r t e r t h a n
c r u d e oil pipelines with a b o u t 230,000 miles. I t i s interesting t o note t h a t in t e r m s
of ton-kilometers, c a r loads and r e v e n u e , c o a l t r a n s p o r t r e p r e s e n t s b y f a r t h e
l a r g e s t commodity g r o u p in r a i l t r a n s p o r t . Thus, although t h e t o t a l length of t h e
r a i l and oil pipeline g r i d s i s equivalent, t h e big d i f f e r e n c e between t h e two
i n f r a s t r u c t u r e s i s t h a t s i n c e t h e 1920s t h e r a i l r o a d system h a s b e e n declining while
oil pipelines have been expanding. Figure 3.5 shows t h e r a p i d i n c r e a s e in t h e
pipeline length f o r c r u d e oil and petroleum p r o d u c t s in t h e United States.
1900
1925
1950
1976
2000
Year
A. Grubler, IIASA, 1986
Figure 3.5
Crude and P r o d u c t s Oil Pipelines Length, U.S.
The expansion of t h e oil pipeline g r i d p a r a l l e l s t h e i n c r e a s e of c r u d e oil s h a r e s
in t o t a l p r i m a r y e n e r g y consumption. Oil r e a c h e d a o n e - p e r c e n t s h a r e in e n e r g y
during t h e 1880s and at t h e same time t h e r a p i d i n c r e a s e in oil pipeline mileage
s t a r t e d and followed exponential t r e n d s until t h e 1930s ( t h e inflection point
o c c u r r e d in 1937). A s if b y coincidence, oil's l a r g e s t competitor, coal, r e a c h e d
maximal s h a r e s in p r i m a r y e n e r g y during t h e same decade. Thus, by 1 9 3 7 a b o u t half
of t h e c u r r e n t length of t h e oil pipeline network w a s a l r e a d y in p l a c e and t h e growth
rates declined slowly. During t h e 1980s t h e length should r e a c h t h e asymptotic
level about t h e same time as c r u d e oil s h a r e s i n t o t a l p r i m a r y e n e r g y s a t u r a t e . The
time c o n s t a n t ( A t ) of t h e expansion of oil pipelines i s 6 2 y e a r s o r half-way between
t h e time c o n s t a n t s f o r t h e expansion of r a i l t r a c k s and s u r f a c e d r o a d s (about 5 0 a n d
7 4 y e a r s , respectively).
Although oil i s s t i l l t h e most important e n e r g y s o u r c e , in t e r m s of p r i m a r y
e n e r g y consumption i t i s slowly being r e p l a c e d by n a t u r a l g a s . Figure 3.4 h a s shown
t h a t t h e amount of a s s o c i a t e d n a t u r a l g a s i s d e c r e a s i n g in total n a t u r a l g a s
production a n d , t h e r e f o r e , t h a t h i g h e r n a t u r a l g a s t r a n s p o r t a n d end-use a r e b a s e d
more on g a s and l e s s on oil technologies. This p r o c e s s i s a l s o r e f l e c t e d in t h e
i n c r e a s e of n a t u r a l g a s t r a n s p o r t and distribution pipelines when c o m p a r e d with oil
pipelines from Figure 3.5. A s mentioned a b o v e , t h e f i r s t n a t u r a l g a s pipeline in
America d a t e s b a c k t o t h e 1820s. The r a p i d expansion of t h e n a t u r a l g a s pipeline
network however, s t a r t e d during t h e 1890s, or a b o u t 20 y e a r s a f t e r t h e growth of
oil pipelines was initiated. Figure 3.6 shows t h a t this 2 0 y e a r s h i f t in time p e r s i s t s
through most of t h e growth c y c l e of t h e n a t u r a l g a s t r a n s p o r t system a n d
distribution i n f r a s t r u c t u r e .
The inflection point, with a b o u t half t h e eventual s a t u r a t i o n l e v e l achieved,
o c c u r r e d in 1 9 6 2 or 2 5 y e a r s a f t e r t h e inflection in t h e growth of oil pipelines.
Since t h e time c o n s t a n t i s a b o u t 5 5 y e a r s , and t h e r e f o r e c o m p a r a b l e t o t h a t of oil
pipelines (62 y e a r s ) , s a t u r a t i o n should a l s o o c c u r more t h a n 20 y e a r s l a t e r during
t h e 2020s. Again this i s symmetrical to t h e r e l a t i o n s h i p between t h e growth p h a s e s
of oil pipelines and oil p e n e t r a t i o n in p r i m a r y e n e r g y . The growth pulse s t a r t e d
when oil achieved a one-precent s h a r e of p r i m a r y e n e r g y , inflection o c c u r r e d
during t h e time when oil became t h e second l a r g e s t e n e r g y s o u r c e (by passing fuel
wood), and s a t u r a t i o n of pipeline length w a s synchronous with t h e s a t u r a t i o n of
m a r k e t s h a r e s . E x a c t l y t h e same p a t t e r n c a n b e o b s e r v e d during t h e growth pulse
of n a t u r a l g a s pipelines by comparing Figure 3 . 6 a n d Figure 3.2. The growth s t a r t e d
towards t h e end of t h e l a s t c e n t u r y when n a t u r a l g a s a c h i e v e d a one-percent s h a r e
in p r i m a r y e n e r g y . The inflection point w a s r e a c h e d in 1 9 6 2 when n a t u r a l g a s
became t h e second l a r g e s t e n e r g y s o u r c e (by passing coal), and s a t u r a t i o n of b o t h
n a t u r a l g a s m a r k e t s h a r e s and length of pipeline should b e achieved during t h e
2020s.
A l a r g e d i f f e r e n c e between t h e growth pulses of oil and n a t u r a l g a s pipelines i s
in t h e length of t h e r e s p e c t i v e t r a n s p o r t and distribution networks. Figure 3.5
gives a s a t u r a t i o n level estimate f o r oil pipeline length of a b o u t 240,000 miles ( o r
a b o u t t h e c u r r e n t length of r a i l r o a d t r a c k s ) , whereas t h e asymptotic l e v e l f o r t h e
length of n a t u r a l g a s pipelines i s estimated at more t h a n 1,300,000 miles (more t h a n
five times h i g h e r ) . F o r t h e time being n a t u r a l g a s is t r a n s p o r t e d almost exclusively
through t h e pipeline g r i d . Oil and petroleum p r o d u c t s however a r e a l s o shipped b y
t a n k e r s , t r a i n s , t r u c k s a n d f o r some military use e v e n by a i r c r a f t . Besides some
smaller quantities of liquefied n a t u r a l g a s and liquid n a t u r a l g a s p r o d u c t s , most
n a t u r a l g a s r e a c h e s t h e consumer e i t h e r in a gaseous form or as e l e c t r i c i t y . The
pipeline network f o r n a t u r a l g a s t r a n s p o r t a n d distribution i s t h e r e f o r e a l s o much
A. Griibler, IIASA, 1986
Figure 3.6
N a t u r a l Gas Pipeline Length, U.S.
l o n g e r t h a n t h a t f o r c r u d e oil and petroleum p r o d u c t s . This of c o u r s e poses t h e
question of w h e t h e r we c a n e x p e c t n a t u r a l g a s to continue t o b e almost exclusively
t r a n s p o r t e d b y pipelines in t h e f u t u r e , especially if i t s p r o j e c t e d use e x p a n d s as
dramatically as i l l u s t r a t e d in Figure 3.2. F o r liquid n a t u r a l g a s p r o d u c t s especially,
i t is likely t h a t o t h e r t r a n s p o r t modes will a l s o b e used, conceivably e v e n a i r c r a f t .
From t h e technical point of view t h e r e a r e no principal o b s t a c l e s to using t h i s
t r a n s p o r t mode f o r e n e r g y , t h e only question i s whether i t would b e economical and
competitive to d o so.
This cannot b e resolved h e r e , but w e mention t h i s a l t e r n a t i v e f o r t h e f u t u r e
because similar solutions were found in t h e p a s t t o meet t h e e v e r increasing need t o
t r a n s p o r t more e n e r g y o v e r longer distances. Both t r a n s p o r t and e n e r g y systems
must meet s t r i n g e r economic and environmental requirements o v e r longer distances
and in s h o r t e r time. A f a s t e r means of t r a n s p o r t , and d e n s e r and c l e a n e r e n e r g y
forms were n e c e s s a r y technological measures in t h e p a s t t o improve t h e
performance of t h e s e systems. We c a n t h e r e f o r e e x p e c t f u r t h e r improvements in
t h e n e a r f u t u r e and t h e s e could b e fulfilled b y a s t r o n g e r r e l i a n c e on n a t u r a l g a s
and a i r c r a f t until b e t t e r solutions and t h e development of completely new systems
are devised during t h e n e x t c e n t u r y . During t h e n e x t f o u r t o five d e c a d e s w e will
r e l y on improved versions of t h e c u r r e n t e n e r g y and t r a n s p o r t systems and
i n f r a s t r u c t u r e s , s i n c e o u r r e s u l t s indicate t h a t t h e time c o n s t a n t s involved in
installing new i n f r a s t r u c t u r e s are in t h e o r d e r of 50 y e a r s .
4 CONCLUSIONS
In a number of examples analyzed in t h i s p a p e r , we h a v e shown t h a t t h e growth
and s e n e s c e n c e of t r a n s p o r t i n f r a s t r u c t u r e s c a n b e d e s c r i b e d as a r e g u l a r p r o c e s s
with logistic s e c u l a r t r e n d s . W e have a l s o o b s e r v e d t h a t t h e time c o n s t a n t s ( A t ) of
t h e s e growth p r o c e s s e s c l u s t e r e d a r o u n d 5 0 y e a r s with a r a n g e of between 3 0 to 75
y e a r s . Considering t h a t t h e quality of h i s t o r i c a l d a t a concerning t h e growth of t h e
t r a n s p o r t i n f r a s t r u c t u r e s l e a v e s much to b e d e s i r e d , i t i s r e m a r k a b l e t h a t t h e f o u r
network or g r i d t r a n s p o r t systems c l u s t e r e v e n more densely between 47 and 75
y e a r s . This includes t h e time c o n s t a n t s f o r railway t r a c k s , s u r f a c e d r o a d s , oil a n d
n a t u r a l g a s pipelines. The time c o n s t a n t s f o r c a n a l s and p e r f o r m a n c e improvements
in a i r c r a f t t r a n s p o r t w e r e s h o r t e r at a b o u t 3 0 y e a r s . In t h e case of c a n a l s a n d
railway t r a c k s s e n e s c e n c e l a s t s much l o n g e r t h a n t h e growth p r o c e s s . The t o t a l
length of c a n a l s , and railways 5 0 y e a r s l a t e r , declined with a much l o n g e r time
constant (of almost 1 5 0 y e a r s ) so t h a t c a n a l s are still in u s e d e s p i t e a c e n t u r y long
decline: t h i s explains t h e long time c o n s t a n t s in t h e substitution of i n f r a s t r u c t u r e s .
Although t h e growth in length of a l l network or g r i d t r a n s p o r t a t i o n i n f r a s t r u c t u r e s
w a s a v e r y f a s t p r o c e s s , from a b o u t 4,000 miles of canals t o a b o u t 4 million miles of
railways, r o a d s a n d airways (a growth of t h r e e o r d e r s of magnitude in a b o u t 1 5 0
y e a r s ) , t h e substitution of t r a n s p o r t i n f r a s t r u c t u r e s ( s e e Figure 2.14) l a s t e d l o n g e r
t h a n t h e a c t u a l growth pulses f o r e a c h of t h e f o u r individual i n f r a s t r u c t u r e s . The
time c o n s t a n t in t h e substitution p r o c e s s i n c r e a s e d from 5 0 y e a r s f o r t h e growth of
railway s h a r e s to almost 9 0 y e a r s f o r s u r f a c e d r o a d s a n d more t h a n 1 3 0 y e a r s f o r
airways, compared with a time c o n s t a n t of 3 0 y e a r s f o r t h e growth pulse of c a n a l s
and a b o u t 5 0 y e a r s f o r railways a n d roads.
A more consistent analysis of t h e evolution of t r a n s p o r t systems a n d t h e i r
i n f r a s t r u c t u r e s would r e q u i r e a comparison of t h e p e r f o r m a n c e a n d s e r v i c e s
provided by t h e d i f f e r e n t modes o v e r long p e r i o d s . F o r t h e time being i t w a s not
possible to r e c o n s t r u c t s u c h a n i n d i c a t o r f o r t.he o v e r a l l t r a n s p o r t system, b u t
Figure 2.15 shows a good p r o x y f o r s u c h a comparison of i n t e r c i t y p a s s e n g e r t r a v e l
during t h e l a s t 37 y e a r s . The substitution of t h e f o u r major modes of long-distance
t r a v e l in t h e United S t a t e s i s a r e g u l a r p r o c e s s t h a t singles o u t a i r c r a f t as t h e
t r a n s p o r t mode with t h e highest growth potential. In t e r m s of t h e dynamics and
g e n e r a l implications, t h i s r e s u l t i s consistent with t h e time c o n s t a n t s o b s e r v e d f o r
t h e growth pulses and substitution of t h e f o u r t r a n s p o r t modes - c a n a l s , railways,
r o a d s and airways.
The r e f i n e d version of t h e p r i m a r y e n e r g y substitutiondynamics(Figure 3.4)
indicates t h a t technological substitution c a n b e c h a r a c t e r i z e d by v e r y r e g u l a r time
c o n s t a n t s provided t h a t t h e h i s t o r i c a l d a t a i s a c c u r a t e enough to provide t h e
information r e q u i r e d f o r f u r t h e r analytical resolution. This i s to a n e x t e n t possible
in t h e case of p r i m a r y e n e r g y consumption b e c a u s e d i f f e r e n t e n e r g y s o u r c e s c a n b e
measured in common (physical, e n e r g y ) units and b e c a u s e t h e i r use i s r e l a t i v e l y well
documented. In this example, t h e a s s o c i a t e d n a t u r a l g a s i s r e a l l o c a t e d t o oil
technology a n d t h e non-associated g a s from g a s tnrells to "gas technology". This
refinement to t h e substitution p r o c e s s so improves t h e r e g u l a r i t y t h a t t h e time
c o n s t a n t s c l u s t e r at a b o u t 7 0 y e a r s f o r a l l e n e r g y s o u r c e s a n d t h e s a t u r a t i o n
i n t e r v a l s between c o a l , oil and g a s technologies a r e a l s o s e p a r a t e d b y a b o u t 5 0
y e a r s . During t h e s a t u r a t i o n p e r i o d s of t h e dominant e n e r g y s o u r c e s , new o n e s are
introduced. Gas technologies are introduced during t h e s a t u r a t i o n of c o a l , and
n u c l e a r e n e r g y during t h e s a t u r a t i o n of oil d u e to t h e addition of a s s o c i a t e d g a s
technologies. The p e n e t r a t i o n rate of g a s technologies i s comparable to t h e
p e n e t r a t i o n r a t e of oil a n d c o a l leading to eventual m a r k e t dominance in t h e n e x t
c e n t u r y . This r e s u l t i s encouraging s i n c e i t indicates a possible n e x t s t e p in t h e
analysis of t h e technological evolution of t r a n s p o r t systems a n d i n f r a s t r u c t u r e s .
A g e n e r a l conclusion i s t h a t technological c h a n g e s , s u c h as t h e substitution of
r o a d vehicles o r locomotives, l a s t a few d e c a d e s , while c h a n g e s in t h e t r a n s p o r t
system and evolution of i n f r a s t r u c t u r e s a r e l o n g e r p r o c e s s e s with time c o n s t a n t s of
between t h r e e and s e v e n d e c a d e s . This means t h a t t h e t r a n s p o r t i n f r a s t r u c t u r e s
themsleves will not c h a n g e d r a s t i c a l l y during t h e rest of t h e c e n t u r y , b u t
c o n c u r r e n t technological c h a n g e s in vehicles, a i r c r a f t and n e c e s s a r y equipment will
impove both t h e p e r f o r m a n c e a n d quality of t h e t r a n s p o r t s e r v i c e s provided by t h e
c u r r e n t systems.
More specifically, r o a d vehicles will remain t h e dominant form of long-distance
t r a s p o r t during t h e n e x t 2 0 y e a r s , b u t t h e importance of airways should i n c r e a s e in
time. Both t r a n s p o r t a n d e n e r g y systems must meet s t r i n g e r economic a n d
environmental r e q u i r e m e n t s o v e r longer d i s t a n c e s a n d in a shorter time. Our
r e s u l t s of t r a n s p o r t i n f r a s t r u c t u r e evolution and e n e r g y substitution indicate t h a t
a i r c a r f t and n a t u r a l g a s r e p r e s e n t evolutionary r a t h e r t h a n r e v o l u t i o n a r y
technologies t h a t could meet t h e s e more s t r i n g e n t requirements. Both a i r c a r f t and
n a t u r a l g a s technologies could meet t h e s e r e q u i r e m e n t s t h r o u g h refinements a n d
improvements in c u r r e n t designs and p r a c t i c e s during n e x t two d e c a d e s , b u t new
solutions must b e developed during t h i s p e r i o d f o r t h e d e c a d e s t h e r e a f t e r . In
p a r t i c u l a r , t h e p e r f o r m a n c e of t r a n s p o r t a i r c r a f t i s estimated t o s a t u r a t e at a b o u t
1.2 million passenger-killometers p e r h o u r which i s r e a c h a b l e with c u r r e n t a i r c a r f t
technology a n d some improvements. However, t h e r e a f t e r a i r c r a f t would b e r e q u i r e d
to e x c e e d t h e s e levels implying e i t h e r l a r g e subsonic l i n e r s (with p e r h a p s a few
thousand p a s s e n g e r s ) o r h y p e r s o n i c t r a n s p o r t with a m o r e modest c a p a c i t y of a few
hundred p a s s e n g e r s . The f i r s t a l t e r n a t i v e a p p e a r s unlikely s i n c e i t would r e q u i r e
v e r y powerful engines a n d t h e i r r a t i n g a p p e a r s to b e s a t u r a t i n g i n unison with t h e
a i r c a r f t p e r f o r m a n c e , ( s e e Figure 2.4). Thus, a new engine ( p e r h a p s t u r b o / r a m o r
ram/scram) could power a h y p e r s o n i c a i r c r a f t of t h e n e x t c e n t u r y witah a
p e r f o r m a n c e of a few thousand passenger-kilometers p e r h o u r . The n a t u r a l g a s
economy a l s o provides t h e n e c e s s a r y liquid hydorgen.
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