Benefit-Cost Analysis of Variable Pricing Projects:
QuickRide HOT Lanes
Mark Burris, P.E., M.ASCE1; and Edward Sullivan, P.E., M.ASCE2
Abstract: Researchers identified a potential methodology for obtaining the incremental societal costs and benefits from a variable pricing
project and applied that methodology to the QuickRide high occupancy/toll 共HOT兲 lanes in Texas. This is one of the longest running
variable pricing projects in the United States and, as such, it provided useful historical data and trends upon which to estimate future
benefits and costs. This analysis found that the incremental societal benefits of QuickRide exceeded incremental societal costs for the time
period considered. A companion paper that used the same methodology to examine the benefits and costs of the SR-91 Express Lanes
found similar results. However, the differences between the benefits and costs were dramatically different for the two projects, indicative
of the relative size of the two projects and the number of travelers impacted. On SR-91, tens of thousands of travelers were impacted on
a daily basis where QuickRide’s impact was limited to approximately 400 travelers per day. Interestingly, the benefit-cost ratios of the two
projects were similar, both between 1.5 and 1.7.
DOI: 10.1061/共ASCE兲0733-947X共2006兲132:3共183兲
CE Database subject headings: Benefit cost ratios; Pricing; Tolls; High occupancy vehicles; Texas; Traffic management.
Introduction
Facing increasing difficulties in funding transportation infrastructure improvements to handle ever increasing traffic congestion
共Schrank and Lomax 2002兲, agencies in charge of highway transportation are increasingly considering the application of value
pricing to their roadways. Value pricing includes 共FHwA 2002兲:
1. Managing demand through tolls that vary by time of day,
day of week, or season;
2. Using flat or variable tolls to efficiently preserve congestionfree use of both new and previously existing spare capacity,
such as in high occupancy/toll 共HOT兲 lanes;
3. Cordon and area pricing with flat or variable tolls;
4. Priced queue-jumps and other congestion-bypass facilities;
5. Converting traditionally fixed costs 共insurance, registration,
etc.兲 to variable costs;
6. Cash out of subsidized employee parking; and
7. Car sharing.
The first four methods listed above have the potential to use tolls
to both help finance infrastructure improvements and manage
congestion—dealing with two of the critical dilemmas facing
transportation agencies. Some pricing methods increase options
available to travelers in the form of both premium and discount
1
Assistant Professor, Dept. of Civil Engineering, Texas A&M Univ.,
3136 TAMU, College Station, TX 77843. E-mail: [email protected]
2
Professor, Dept. of Civil and Environmental Engineering, California
Polytechnic State Univ., San Luis Obispo, CA 93407. E-mail:
[email protected]
Note. Discussion open until August 1, 2006. Separate discussions
must be submitted for individual papers. To extend the closing date by
one month, a written request must be filed with the ASCE Managing
Editor. The manuscript for this paper was submitted for review and possible publication on November 12, 2004; approved on May 4, 2005. This
paper is part of the Journal of Transportation Engineering, Vol. 132,
No. 3, March 1, 2006. ©ASCE, ISSN 0733-947X/2006/3-183–190/
$25.00.
services such as access to a faster lane 共methods 2 and 4兲, and
discounts for adjusting time of travel 共methods 1 and 3兲. Variable
pricing is a feature of many value pricing projects, where tolls
vary by time of day. These pricing strategies reduce traffic
demand for the most congested times and locations, improving
traffic flow.
In theory, the use of variable pricing in the form of marginal
cost pricing has been shown to maximize net societal benefits
共Walters 1968; Hau 1992; Small and Gomez-Ibanez 1997;
Mohring 1999兲. These benefits occur because the total cost of
travel 共marginal social cost兲 exceeds the average private cost paid
by drivers during congested periods 共see Fig. 1兲. This disparity
leads to an inefficiently high demand 共q1 in Fig. 1兲 and a welfare
loss 共the hatched area of Fig. 1兲. The optimal traffic flow 共q2兲
Fig. 1. Optimal pricing of transportation
JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006 / 183
occurs at the point where the demand for travel 共Curve D-D in
Fig. 1兲, which measures the marginal benefit to users of each
additional trip, intersects the marginal social cost curve. At the
optimum flow, q2, any increase or decrease in traffic would
decrease the net societal benefits derived from the use of the road.
In theory, the optimal flow of traffic can be achieved if drivers are
charged a toll of ␶.
Planners, engineers, and economists have developed theoretical models to predict the impact of congestion pricing 共both in its
pure marginal social cost pricing form and using variations of
marginal social cost pricing兲. Applying these models to actual
traffic conditions, researchers predicted the resulting societal
costs and benefits 共Hyman and Mayhew 2002; May et al. 2002;
Santos and Rojey 2003兲. In almost every case, societal benefits
exceeded societal costs—although the impacts were often regressive to neutral with respect to the relative benefits enjoyed by
different income groups. To improve the equity of the pricing
program some writers examined various toll revenue allocation
schemes 共Small 1992; Litman 1999; Parry and Bento 1999兲.
Despite these findings, many transportation agencies remain
reluctant to proceed with variable pricing projects. Part of this
reluctance may stem from the lack of actual empirical data on the
benefits and costs of operational variable pricing projects. This
lack of actual data is not surprising since only 19 variable pricing
projects have been implemented 共Burris and Pendyala 2002兲, and
many of those have been implemented too recently to provide the
data required for a benefit-cost analysis 共BCA兲. This research was
undertaken to provide an empirical reference point by performing
a BCA on one of the US’s longest running projects:
the QuickRide Program 共HOT lanes兲, in Houston 共see Fig. 2兲.
共A companion paper used the same methodology to perform a
BCA for the SR-91 Express Lanes.兲
In analyzing this project, researchers used 4 years of historical
data to derive historical costs and benefits and to project future
costs and benefits. Based on these data, net societal benefits
exceeded costs for the period considered, although the difference
was small.
The next section of the paper includes an overview of the BCA
methods used. In the succeeding section the benefits and costs of
the variable pricing project are documented. The last section of
the paper includes a summary and conclusion.
Framework for the Benefit Cost Analysis
In this research, the net incremental societal benefits and costs of
a variable pricing project were quantified. This included the incremental benefits and costs resulting from the implementation of
the variable pricing project, but did not include any transfers of
wealth among different groups. In such an analyses it is critical to
carefully define the attributes of the “base case” scenario. This
scenario did not exist, but rather it is what would have likely
occurred if the variable pricing project had not been undertaken.
As such, it provides the reference point against which the incremental societal costs and benefits of the variable pricing project
are measured. Our base case assumed that the HOT lanes in
Houston continued to operate as HOV lanes, without ever incorporating the option of toll paying travelers 共see the following
section for details specific to the individual project兲.
The variable pricing project examined here, along with most
pricing projects around the world, rely on electronic toll collection 共ETC兲 for vehicle identification and toll payments. ETC
equipment has a limited life span, and therefore benefit-cost
analyses of ETC projects 共along with other intelligent transportation system projects兲 typically examine benefits and costs for
a 10-year time frame 共USDOT 2002兲. This research also used
a 10-year time frame for cost and benefit streams. Although
this may be seen as conservative, it was appropriate since
one of the HOT lanes was slated to undergo major reconstruction and expansion after this time period. All benefits and
costs were converted to year 2002 dollars using discount and
inflation rates published by the federal government 共real⫽3.1%,
nominal⫽5.1%, inflation⫽1.9%兲 共OMB 2002兲.
Benefits
In general, the benefits travelers derive from making trips is
measured by the area formed between the demand curve 共D-D in
Fig. 1兲 and the horizontal line indicating the cost of travel at the
given demand 共line p1 in Fig. 1兲. If a change in transportation
infrastructure or travel options causes the area between these
two curves to increase then the change results in a net benefit
for those travelers. As discussed previously, society as a whole
benefits to the maximum extent possible when the cost of the
trip equals the marginal social cost—eliminating the welfare
loss caused primarily by the additional time penalty each new
vehicle imposes on existing drivers under congested conditions.
Unfortunately, the shapes of these curves are generally unknown
and calculating a change in benefits often amounts to estimating
the change in travel costs for travelers and aggregating these
changes.
It is common to estimate user cost changes due to changes in
travel time savings, vehicle operation and ownership costs, and
safety improvements 共USDOT 2000; AASHTO 2003兲. However,
cost savings associated with safety were not examined here
because the accident rates for the travel options were similar and
no benefits were assumed from a safety aspect. One additional
item examined here was costs associated with emissions, due to
the increased interest in such impacts.
Travel Time Savings
The benefits of this variable pricing project, and the majority
of transportation improvements, are dominated by travel time
savings. Although it is relatively straightforward to estimate the
amount of travel time saved due to a transportation improvement,
it is far more difficult to determine the value of that travel time
saved. A great deal of research has focused on determining
appropriate values of time 共VOT兲 共Calfee and Winston 1998;
Small et al. 1999; Bates et al. 2001; Hensher 2001兲. Much of this
research has found that the values of time for commute trips range
from 20% to over 50% of the drivers’ wage rates 共USDOT 2003兲.
These values have been shown to increase with increased traffic
congestion 共Small et al. 1999兲, and there was considerable traffic
congestion in the free lanes beside the variable pricing project
examined.
The VOT was further refined in this research based on the
premise that, other things being equal, people who chose to pay
tolls to avoid congestion must have had values of time at least
equal to the toll divided by the amount of time saved. Similarly,
people who chose not to pay tolls to avoid congestion would
usually be expected to have had values of time less than the
toll divided by the time that could have been saved. However,
this simple premise was complicated by eligibility issues, such as
the requirement to have a transponder in order to use these toll
facilities.
184 / JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006
Table 1. Unit Values of Emission Reductions
Delucchi
Pollutant
Low
共$/kg兲
a
High
共$/kg兲
Small and Kazimi
and Levinson b
共$/kg兲
1.59
23.34
NOx
VOC
0.13
1.45
CO
0.01
0.10
PM10
a
Delucchi 共2000兲.
b
Values obtained by Small and Kazimi
共2002兲.
Values used
in this analysis
共$/kg兲
1.33
1.71
0.0063
1.59
1.45
0.01
12.17
共1995兲 as modified by Levinson
the default value used in the Federal Highway Administration
共FHwA兲 STEAM model 共FHwA 2003兲. Costs were inflated
according to an average health care index 共+3.5% per year,
USHCFA 2001兲 to calculate values for the entire evaluation
period.
Fig. 2. Houston’s HOT lanes 共figure created by John Hobbs,
used with permission兲
Vehicle Operating and Ownership Costs
Another potential benefit derived from roadway improvements
is the reduction in vehicle operating and ownership costs. In this
application, since the distance traveled for each option was
identical, it was assumed that there would be no significant
difference in ownership costs and the bulk of operational cost
savings would be derived from any reduction in fuel consumption. Based on the changes in speeds caused by the variable
pricing project, the changes in fuel consumption were estimated
using Fig. 3 共West et al. 1999兲.
The total change in fuel consumption was converted to a dollar
value based on the price of fuel at the pump 共approximately $1.50
in 2000兲. Taxes were subtracted from the pump price because
taxes are transfers of wealth and should not be included in calculating incremental societal costs and benefits. The net benefit from
reducing fuel consumption was valued at approximately $1.12 per
gallon 共year 2000 dollars兲.
Emissions
The final benefit category considered was the change in vehicle
emissions. The changes in emissions were found using Mobile 5b
in Houston and the California EMFAC model for SR-91 in the
companion paper 共CARB 1996; Barth et al. 2001; CARB 2003兲.
Mobile is the mobile source emissions estimation program used in
the majority of the United States while EMFAC is specifically
calibrated for the California vehicle fleet. Once the changes in the
quantities of pollutants 关nitrous oxides 共NOx兲, volatile organic
compounds 共VOC兲, carbon monoxide 共CO兲, and 共in California兲
particulate matter 共PM10兲兴 were determined, the values of these
changes were estimated using default values shown in Table 1.
To convert emissions to monetary values, the costs associated
with most pollutants were obtained from research done by
Delucchi 共2000兲 and Small and Kazimi 共1995兲 共see Table 1兲. Both
of these sources based their costs of emissions on the cost
of health care to treat diseases related to the emissions of
motor vehicles. The values used in this analysis were on the
conservative end of the estimates. In the case of PM10 emissions
共in California兲, the unit cost of $12.17/kg was adopted, which is
Costs
Incremental costs were more straightforward to estimate. All costs
共excluding transfers兲 that the agency incurred due to the project
were included. Start up costs were amortized over the 10 years
evaluation period and added to any operation and maintenance
costs of the project over and above costs that would have
occurred under the base case scenario.
Benefit-Cost Analysis of Houston Quickride
For the analysis period, the Houston QuickRide project consisted
of high occupancy/toll 共HOT兲 lanes on the Katy Freeway 共I-10兲
and Northwest Freeway 共US 290兲 in Houston 共see Fig. 2兲. Each
highway had one barrier-separated reversible high occupancy
vehicle 共HOV兲 lane that was open on weekdays 5–11 a.m.
inbound and 2–8 p.m. outbound. Normally open to HOV 2+
vehicles, the lanes were restricted to HOV 3+ vehicles during
6:45–8:00 a.m. on both freeways and 5:00–6:00 p.m. on Katy
Freeway. However, HOV 2+ drivers who registered for the
QuickRide program could use the lanes during these hours if they
paid a $2 toll per trip. In this way the toll paid by HOV2 travelers
on the HOV lane varied by time of day, with the peak period
costing $2 and the off-peak having no toll.
The HOV lane on the Katy Freeway was constructed in 1984.
The lane was originally restricted to buses and vanpools but the
lane operator quickly relaxed these restrictions to accept any
HOV 2+ vehicle. By 1988, the need to alleviate congestion led to
the additional occupancy restrictions during the morning peak
hour. The afternoon peak period followed shortly after. The same
restrictions were later placed on the HOV lane on the Northwest
Freeway during the morning peak period. This was how the HOV
lanes operated for several years prior to QuickRide beginning in
mid-January 1998 on the Katy Freeway and November 2000 on
the Northwest Freeway.
Prior to QuickRide, the increased occupancy restriction
eliminated HOV lane congestion, but resulted in significant
excess capacity 共Burris and Hannay 2003兲. This was chosen as
the base case against which the costs and benefits of QuickRide
were compared. In this base case, which assumed no QuickRide,
HOV2 vehicles could not legally use the HOV lane during the
HOV 3+ restricted periods. The analysis covered the time period
JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006 / 185
Table 2. Travel Alternatives to QuickRide
Travel alternative
Table 3. 2001 Travel Time Savings
Estimated percentage of trips
that used this travel method
prior to QuickRidea
Travel by bus on the HOV or GPLs
8
HOV2 during off-peak on HOV lane
7
HOV2 during peak on GPLs
26
HOV3+ on HOV lane
2
SOV on GPLs
54
Other
3
a
These estimates were obtained from a 1998 survey of QuickRide
enrollees.
from mid-January 1998 to mid-January 2008, corresponding to
10 years of QuickRide usage on the Katy Freeway and just over
7 years on the Northwest Freeway.
QuickRide Benefits
The number of QuickRide trips was determined using a database
that contained all recorded QuickRide trips. Future QuickRide
usage was estimated to be the average of volumes for the years
2002 and 2003. This was likely a conservative estimate as it
assumed a 0% growth in the number of QuickRide trips.
For each of these trips it was assumed that the benefits derived
from using QuickRide exceeded the benefits derived from the
travelers’ alternative methods of travel. The most probable travel
alternatives are listed in Table 2. Note that the data in Table 2 can
be considered only rough estimates since they were obtained in
1998 and did not include US 290 travelers.
Each of these travel options provided a reduced utility for
travelers with respect to using QuickRide. It is extremely difficult
to both 共1兲 quantify the number of current QuickRide trips
that would fall into each of the categories in Table 2 and 共2兲 to
quantify the additional benefits of a QuickRide trip versus each
alternative. Therefore, in this analysis, the benefits of QuickRide
were derived by comparing a QuickRide trip to a single occupancy vehicle 共SOV兲 trip at the same time on the general purpose
lanes 共GPL兲. Thus the additional benefits derived from using
QuickRide compared to SOV travel were assumed to be similar to
the benefits of QuickRide compared to other travel options. For
example, this assumes benefits derived by HOV2 travelers who
兺
segments
兺
冤
Freeway
Time
Katy a.m.
6:45–7:00
7:00–7:15
7:15–7:30
7:30–7:45
7:45–8:00
Weighted average 共a.m.兲
11.1
19.5
23.6
23.5
10.2
29.76
27.25
24.48
23.37
24.79
25.50
53.98
59.81
60.21
60.11
59.48
59.22
11.6
15.4
18.6
20.1
18.1
17.3
Katy p.m.
5:00–5:15
5:15–5:30
5:30–5:45
5:45–6:00
Weighted average 共p.m.兲
7.0
14.2
12.2
6.7
28.35
26.13
26.97
28.61
27.19
57.19
58.34
57.63
58.70
57.98
13.7
16.2
15.2
13.8
15.0
Northwest a.m. 6:45–7:00
7:00–7:15
7:15–7:30
7:30–7:45
7:45–8:00
Weighted average 共a.m.兲
2.8
8.0
14.0
16.2
7.2
34.36
31.89
28.72
27.44
30.09
29.35
53.01
57.91
58.85
59.52
59.82
58.72
6.3
8.6
10.9
12.0
10.1
10.5
used to travel during the off-peak period but could now drive at
their preferred time of travel in the HOT lanes using QuickRide
were similar to the benefits derived by an SOV peak-period traveler switching to HOV2 and using the HOT lane as a QuickRide
traveler.
Value of Travel Time Savings
To determine the travel time savings gained by using the HOT
lanes, vehicle travel times on both the GPLs and the HOT lanes
were analyzed. The dataset used included several million speed
entries for individual vehicles based on their actual travel times
between several automatic vehicle identification 共AVI兲 readers
placed along the HOT and general purpose lanes 共GPLs兲 of the
Houston freeways 共data available at http://traffic.tamu.edu兲. Using
these data, the average travel speeds on both the HOT and GP
lanes were found for each 15-min period, on each highway, for
each year, using Eq. 共1兲
兺 observations
users
兺
n=1
work days
average speed =
Eq. 共1兲 was used to determine the average space mean speed
共Banks 2002兲 weighted by the number of observations for a given
segment and the length of that segment. To determine the travel
time savings, these average speeds plus the average distance
traveled on the HOT lanes were required. Survey data from
QuickRide users, taken in 1998, was used to find that the average
GPL
HOT lane
average average
Time
Vehicles speed
speed
savings
per day 共mph兲
共mph兲
共min/veh兲
1
⫻ # observations
speedn
兺
冥
⫻ lengthsegment
lengths
segments
# work days in year
共1兲
distance traveled on the Katy HOT lane by QuickRide users
was 11 mi 共2.3 mi less than the length of the facility兲. For the
Northwest Freeway, data on entry and exit of all vehicles on the
HOT lane was used since there were no data on QuickRide users
alone. Assuming QuickRide trips were of similar length as all
HOT lane trips, the average distance traveled was 10.6 mi 共3.1 mi
186 / JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006
Fig. 3. Fuel consumed versus travel speed 共data from West et al. 1999兲
less than the length of the facility兲. Using these data the average
travel time savings of travel in the HOT lanes versus the GPLs
was determined. Next, the average carpool formation time of
4.33 min 共from the survey of drivers兲 was subtracted to account
for the time lost in forming carpools. These average travel time
savings for each year 共see Table 3 for representative values for a
single year兲 were entered into Eq. 共2兲 to determine the total value
of travel time savings.
10
VTTS =
兺
y=1
冋
9
VoTy ⫻
共TSyi ⫻ Vehyi兲 ⫻ QRdaysy
兺
i=1
册
共2兲
where VTTS⫽value of travel time savings 共$兲 for all QuickRide
users 共in 2002 dollars兲; 1–10; these indicate the 10 years of
QuickRide usage examined 共the first three on US 290 had
0 VTTS兲; VoTy⫽value of time in year y⫽$15.56 per person-hour,
$31.13 per vehicle-hour in 2002 and adjusted by the discount rate
共3.1%兲 for other years. This was based on 35% of the wage
rate of QuickRide users 共from the survey兲 and $0 for children
共who comprise approximately 21% of QuickRide carpool passengers兲; i = 1 – 9; these indicate the nine, 15-min time segments 共as
shown in Table 3兲 for the Katy Freeway or i⫽1–5 for the five,
15-min time segments on the Northwest Freeway; TS⫽travel time
saved by traveling in the HOT lane compared to the GPLs 共h兲;
Veh⫽average number of vehicles per day that used QuickRide
共vehicles/day兲; and QRdays⫽number of QuickRide days per year,
typically just over 250 per year. The total value of travel time
savings over the entire period 共converted to year 2002 dollars兲
was $2.36 million.
Fuel Usage
The fuel saved by QuickRide users versus GPL users was estimated using travel speeds from the GPLs and HOT lanes. The
localized travel speeds were converted to fuel use 共gal/mil兲 using
Fig. 3. The results for the HOT lanes were likely to be more
accurate than for the GPLs because vehicle speeds on the HOT
lanes contained much less variability 共see Fig. 4兲 and therefore
Fig. 4. Speed distributions on the HOT and GP lanes
JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006 / 187
Table 4. 2003 Fuel Consumption 共FC兲 Savings on Katy Freeway
Table 5. Weighted Average Emission Savings 共2002兲
FCHOT
Daily
Vehicles
FCGPL
共per day兲 共gal/veh mi兲 共gal/veh mi兲 fuel savings 共gal兲
Time
6:45–7:00 a.m.
7:00–7:15 a.m.
7:15–7:30 a.m.
7:30–7:45 a.m.
7:45–8:00 a.m.
5:00–5:15 p.m.
5:15–5:30 p.m.
5:30–5:45 p.m.
5:45–6:00 p.m.
Total
8.59
0.024
0.022
15.68
0.025
0.021
21.22
0.026
0.020
22.71
0.027
0.021
15.81
0.027
0.021
9.28
0.032
0.021
17.43
0.037
0.021
15.97
0.037
0.021
11.35
0.034
0.020
138.04
⫻254 days⫻ $1.13/ gal=
0.3
0.7
1.4
1.6
1.1
1.1
3.1
2.8
1.7
13.8
$3,980
Katy a.m.
Katy p.m.
US 290 a.m.
10
兺
y=1
再
9
CoFy ⫻
⫻ QRdaysy
冎
VOC
共g/veh兲
CO
共g/veh兲
NOx
共g/veh兲
5.3
6.1
3.6
35.2
67.0
7.9
−6.8
−5.0
−6.9
2.
the AVI readings of travel times between two AVI locations
共1–5 mi apart depending on location兲 more accurately represented
the actual vehicle speeds.
Conversely, vehicle speeds on the GPLs during these times
were highly variable. In this case, an average speed of 15mph
over a freeway segment was likely indicative of stop and go
traffic where speeds actually varied from near 0 to 30 mph. Since
fuel usage increases rapidly at speeds below 25 mph the true fuel
usage on the GPLs was likely greater than what was found using
average speeds. A more accurate estimate would use second-bysecond speed profiles, but such data were unavailable. Therefore a
conservative estimate of fuel savings was derived using Eq. 共3兲
FS =
Time
period
关共FCML − FCHOT兲yi ⫻ Vehyi ⫻ D兴
兺
i=1
共3兲
where FS⫽value of fuel savings 共$兲 for all QuickRide users 共in
2002 dollars兲; y⫽1–10; these indicate the 10 years of QuickRide
usage examined; CoFy⫽cost of fuel in year y⫽$1.116/gallon in
2000 共$1.50/gallon at the pump $0.384/gallon in taxes兲 and
adjusted by the discount rate of other years; i⫽1–9; these indicate
the nine, 15-min time segments 共as shown in Table 4兲 for the Katy
Freeway or i⫽1–5 for five, 15-min time segments for the Northwest Freeway; FC⫽fuel consumed on the GPLs or the HOT lane
共gallons per mile兲; Veh⫽average number of vehicles per day that
used QuickRide 共vehicles/day兲; D⫽average distance traveled per
vehicle, 11 mi on Katy, 10.6 mi on US 290; and QRdays⫽number
of QuickRide days per year, typically just over 250 per year.
These calculations resulted in a total fuel savings of $33,700.
An example of the results from 1 year is shown in Table 4.
Emissions
The final benefit examined was the change in emissions from
vehicles using QuickRide. Once again, the vehicle speeds
were used to calculate the changes in emissions from a vehicle
traveling on the GPLs versus one traveling on the HOT lane. Note
that this method should have also provided a conservative
estimate, for two reasons:
1. As with fuel consumption, vehicle emissions increase significantly in stop and go traffic. The fact that speed data
contained only average speeds over 1–5 mi segments
reduced the ability to accurately account for stop and go
conditions on the GPLs; and
If QuickRide did not exist, over half of the QuickRide
travelers would have chosen to travel in SOVs. Therefore
each QuickRide vehicle corresponded to more than one
vehicle removed from the GPLs. However, we conservatively assumed a one-to-one vehicle replacement in this
calculation.
Calculation of the changes in emissions was done in much
the same manner as fuel consumption, as shown in Eq. 共4兲 and
Table 5
3
PR =
10
兺
兺
p=1 y=1
再
9
CoPpy ⫻
⫻ QRdaysy
冎
关共PEML − PEHOT兲yi ⫻ Vehyi ⫻ D兴
兺
i=1
共4兲
where PR⫽value of pollution reduction 共in 2002 dollars兲 due to
all QuickRide users; p⫽1–3; these indicate the three pollutant
species 共VOC, NOx, SO2兲 examined; y⫽1–10; these indicate the
10 years of QuickRide usage examined; CoPy⫽cost of pollutant
共see Table 1兲 共$/kg兲 in year y 共adjusted for other years using the
discount rate of 3.1%兲; i⫽1–9; these indicate the nine, 15-min
time segments 共as shown in Table 4兲 for the Katy Freeway or
i⫽1–5 for five, 15-min time segments for the Northwest Freeway;
PE⫽pollutant emitted on the GPLs or the HOT lane as a function
of speed 共based on Mobile 5a兲 共kg per mile兲. Veh⫽average number of vehicles per day that used QuickRide 共vehicles/day兲;
D⫽average distance traveled per vehicle, 11 mi on Katy, 10.6 mi
on US 290; and QRdays⫽number of QuickRide days per year,
typically just over 250 per year.
An example of this is shown in Table 6. The total benefit from
reduced vehicle emissions on both freeways was found to be
−$1,100. The shift from the GPLs to the HOT lane reduced the
overall volume of pollutants. However, it was the pollutant with
Table 6. Values of Emissions Savings: Katy Freeway
Total emissions savings
Year
1998
1999
2000
2001
2002
2003
2004a
2005a
2006a
2007a
2008a
Total
a
Projected.
188 / JOURNAL OF TRANSPORTATION ENGINEERING © ASCE / MARCH 2006
QR
共days兲
VOC
共$兲
CO
共$兲
NOx
共$兲
Total
共$兲
238
253
254
252
253
254
253
253
253
253
15
164
192
181
224
264
411
389
395
400
406
24
2
0
0
5
15
26
24
25
25
26
2
−316
−416
−387
−405
−321
−367
−353
−358
−363
−369
−22
−150
−224
−205
−175
−42
70
60
61
62
63
4
−475
Table 7. Summary of Costs and Benefits for QuickRide 共2002 Dollars兲
Benefit category
Value
Travel time savings
Fuel savings
Emissions savings
$2,360,000
$33,700
$−1,100
Costs
Start up costs
Operations and maintenance
$477,900
$1,010,700
Benefit cost ratio
1.61
the smallest health impact, and therefore lowest economic impact,
CO, that was reduced the most. The most costly pollutant, NOx,
increased due to the HOT lane vehicles traveling at speeds near
60 mph. This caused the negative total economic value of the
change in emissions. As stated earlier, this was a conservative
estimate of the reduction in emissions. Due to this fact, the actual
result may have been closer to neutral.
Acknowledgments
QuickRide Costs
The costs of the QuickRide project included agency start up costs
plus annual operation and maintenance costs. The $2 toll and
$2.50 monthly enrollment fee were not included as they were
simply transfers from the driver to the QuickRide agency. Additionally, the travel speed and level of service on the HOT lane
were not degraded so previous users of the HOT lane did not
experience additional travel costs due to the presence of QuickRide participants. Conversely, the limited number of QuickRide
enrollees leaving the GPLs did not significantly impact travel on
those lanes and therefore no benefits were calculated for GPL
users.
The Texas Department of Transportation and Houston
METRO supplied cost figures for QuickRide from 1997 to 2002.
These cost figures included all costs incurred due to the QuickRide program over and above the HOV lane operations 共the base
case兲. Based on these figures, researchers attempted to separate
start up costs and annual costs and arrived at the following cost
estimates:
Average monthly operation
and maintenance costs:
Katy start up costs:
US 290 start up costs:
Total costs:
thousands of travelers were impacted on a daily basis where
QuickRide’s impact was limited to approximately 400 travelers
per day. Interestingly, the benefit-cost ratios of the two projects
were similar, both between 1.5 and 1.7. Although these ratios
were similar for these two projects, other variable pricing projects
are likely to yield different results.
The analysis also found that the majority of benefits were
derived from travel time savings. The VOT was the key factor in
determining total benefits. Although a great amount of research
has been done to estimate VOT, the bulk of it has been through
stated preference surveys, often analyzing different mode choices.
More research is needed on VOT derived from operational toll
projects, particularly ones where the toll varies by time of day.
This will allow researchers to better quantify both the VTTS and
the benefits derived by travelers who gain the option of traveling
congestion-free at their preferred time of day. This data may be
derived from existing variable pricing projects and, in turn, help
quantify the benefits of proposed future projects.
$8,263 共in 2002 dollars兲
$362,389 共in 1997 dollars兲
$52,482 共in 2000 dollars兲
$1,488,600 共in 2002 dollars兲
QuickRide Summary
The total benefits of QuickRide over the 10 year period exceeded
costs by 61% 共see Table 7兲.
Conclusions
This analysis of QuickRide, one of the earliest operational variable pricing projects in the U.S., found that the incremental
societal benefits exceeded costs. Similar results were found in a
companion paper that investigated the corresponding benefits
and costs for the SR-91 Express Lanes. The magnitudes of the
differences in benefits and costs were dramatically different for
the two projects, indicative of the relative size of the two
projects and the number of travelers impacted. On SR-91, tens of
The writers would like to thank the FHwA’s Value Pricing
Program for support of the projects analyzed in this research.
Additionally, Houston METRO and TxDOT partnered with the
FHwA in supporting these projects and the efforts made by all of
those agencies are gratefully acknowledged. Additional thanks to
Doug Lee and two anonymous reviewers for examining an earlier
version of this paper. Any errors and omissions are entirely the
fault of the writers.
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