•
Chapter 9
STRATEGIES AND NETWORK NEEDS
Session Objective
The objectives of this session are to enable participants to
• Relate the results of condition assessment to the most appropriate
maintenance and rehabilitation strategy for a road section.
• Identify overall network needs to arrive at funding requirements.
Determining Strategies
•
•
Once the pavement condition information is collected it must be analyzed
to determine the maintenance and rehabilitation needs. This analysis must be
made using certain standards, along with sound engineering judgment. The
analysis should look at the measured condition of each section and determine
the cause of the observed distress and how it can best be corrected.
A basic concept of pavement management is that maintenance resources
should be spent on only those pavements that are in good enough condition to
warrant such expenditures. It should be pointed out that a pavement will
generally perform well for a number of years. Once the deterioration process
begins, however, the pavement fails very quickly. Deficiencies which were
originally in the pavement surface can quickly snowball and become structural
deficiencies. When this occurs, the cost of pavement rehabilitation increases
dramatically in a relatively short period of time.
Given the present condition of a pavement, there is a maintenance and
repair strategy that is most appropriate. "Strategy" refers to an overall
approach to maintenance and repair actions. It is helpful to avoid confusing
(1) how an activity is funded with (2) this concept of strategy. It really
doesn't matter if a surface treatment, for example, is applied with in-house
forces or by contract. As far as long-term performance of the pavement is
concerned, it only matters that the proper preventive maintenance activity was
applied at the right time .
9-1
There are five general strategies that can be considered for paved
surfaces:
Routine Maintenance - For roads in reasonably good condition, routine
maintenance is generally the most cost-effective use of funds. If at all
possible, all routine maintenance needs should be funded each year. Routine
maintenance usually includes local patching, crack sealing, and other
relatively low-cost actions. Distresses such as isolated medium or high
severity bumps or potholes that may have a considerable negative impact on the
performance of a section are usually corrected first.
Preventive Maintenance - This strategy is a more expensive activity
designed to arrest deterioration before it becomes a serious problem. Surface
seals are excellent examples of preventive maintenance. A common source of
poor performance of seals is inadequate repair of existing distress before
sealing, so extensive repair work may also be included in preventive
maintenance. Repair and seal needs will probably have to be programmed over
several years in order of priority because of the expense. Routine
maintenance should be performed on those sections that are not programmed for
the current budget year.
•
Deferred Action - The road sections which fall into this category receive
minimum funds for the current budget year. These sections are beyond the
point where preventive maintenance will be effective but have not yet
deteriorated to the point of needing rehabilitation. Selecting this strategy
is deferring action, so an agency must be prepared to fund rehabilitation or
reconstruction when it becomes necessary. This strategy is normally not
appropriate for aggregate surfaced roads.
Rehabilitation - Rehabilitation usually includes overlays or extensive
recycling. Funding for completion of these major projects may depend upon
federal or other outside sources. The established priorities should be
followed if possible, although managers should realize that priorities may
change for a variety of reasons. For example, estimates for a particular job
may exceed available funds, insurmountable administrative restrictions on
funds may exist, or very valid political reasons to change priorities may
9-2
•
•
occur. Sections that fall into this strategy category that are not programmed
for the current budget year should fall into the deferred action strategy.
Reconstruction - The comments on rehabilitation projects also apply to
reconstruction projects. The main difference is in the costs that might be
expected. Reconstruction would involve complete removal and replacement of a
failed pavement and might also involve features other than just pavement such
as widening, realignment, traffic control devices, safety hardware, and major
drainage work. Lead times of five to ten years might be required because of
the significant nature of required investments and the time necessary to
develop plans, acquire right-of-way, and other funding.
Typical Actions - Exhibits 9-1 through 9-4 list typical actions that
might be performed within each strategy.
The proper maintenance and repair strategies are best selected using a
•
•
life-cycle cost analysis. This process can be time consuming if attempted for
every decision for every pavement section. If a detailed economic analysis is
not used, the most appropriate strategy can be selected using a logic scheme
as suggested in Exhibits 9-5 and 9-6. Such a scheme, of course, can be
refined with a life-cycle analysis using average costs for typical activities,
then using the resulting decision criteria as the standard for all sections.
If such an approach is taken, different criteria for each pavement type can be
selected.
It should be noted that there is considerable overlap of possible
strategies on the PCI performance curve. In the example shown in Exhibit 9-5,
there are two or three possible strategies for any PCI value from 25 to 15.
This is a very realistic approach because the deterioration of pavements is a
gradual process. A change in just a few PCI points will not usually make one
strategy preferable over another.
Within certain ranges of condition, one must look at the factors that
went into the overall condition rating. Predominately surface distress such
as weathering, ravelling, or bleeding would indicate a need for preventive
maintenance over other strategies. On the other hand, if most of the
condition rating is a result of structural distress such as alligator
cracking, potholes, or failed patches, then it may be best not to expend
preventive maintenance funds and plan a rehabilitation effort. Roughness can
also help determine strategy decisions.
9-3
Exhibit 9-l'
TYPICAL ACTIONS
AGGREGATE SURFACE
Strategy
•
Recommended Actions
A. Routine Maintenance
• Blading
• Local repairs
• Pothole filling
B. Preventive Maintenance
• Ditch cleaning
• Dust control
• Strategy A actions as necessary
• Spot aggregate addition
D. Rehabilitation
• Scarifying and recompaction
• Strategy A and B actions as necessary
• Stabilization
• A structural addition of aggregate (2
inches or more)
E. Reconstruction
•
• Strategy D actions as necessary
• Removal and replacement of the entire
pavement structure
• Paving with a surface treatment,
asphaltic concrete or portland ceme~t
conc rete.
• Geometric, safety, and traffic
improvements as necessary
9-4
•
•
Exhibit 9-2
TYPICAL ACTIONS
FLEXIBLE PAVEMENTS
Strategy
Recommended Actions
A. Routine Maintenance
•
•
•
•
B. Preventive Maintenance
• Strategy A and C actions as necessary
Crack sealing
Skin patching
Local repairs
Strategy C actions as necessary
• Surface seals
• Thin overlays
•
C. Deferred Action
• Patching of high severity potholes,
shoving, corrugations and rutting
D. Rehabilitation
• Strategy A, B, and C actions as
necessa ry
• Removal of a portion of the surface if
necessa ry
• Structural overlay
E. Reconstruction
• Strategy D actions as necessary
• Removal and replacement of the entire
pavement structure
• Geometric, safety and traffic
improvements as necessary
9-5
Exhibit 9-3
TYPICAL ACTIONS
RIGID PAVE'MENTS
Strategy
A. Routine Maintenance
Recommended Actions
•
•
•
Crack sealing
Local repa irs of low to medium severity
faulting, blow-ups and divided slabs
Strategy C actions as necessary
B. Preventive Maintenance
• Strategy A actions necessary
• Limited slab replacement
• Clean and seal joints
• Slab stabilization
• Strategy C actions as necessary
C. Deferred Action
• High
• High
D. Rehabilitation
•
severity blow-up repa i r
severity divided slab repair
Strategy A, B, and C actions as
necessary
• Up to 50 percent slab replacement
• Grinding or milling to restore
rideabi 1ity
• Structural overlay
E. Reconstruction
•
• Strategy D actions as necessary
• Greater than 50 percent slab replacement
• Removal and replacement of entire
pavement structure
• Geometric, safety, and traffic
improvements as necessary
9-6
•
Exhi bit 9-4
TYPICAL ACTIONS
COMPOSITE PAVEMENTS
•
Strategy
Recommended Actions
A. Routine Maintenance
•
•
•
•
B. Preventive Maintenance
• Strategy A and C actlons as necessary
Crack sealing
Skin patching
Local repairs
Strategy C actions as necessary
• Surface seals
• Thin overlays
• Slab stabilization
•
C. Deferred Action
• Patching and repairs of high severity
blow-ups, and bond loss
D. Rehabilitatlon
• Strategy A, B, and C actions as
necessary
• Removal of overlay portion
• Joint repairs
• Structural overlay
E. Reconstruction
•
• Strategy 0 actions as necessary
• Grinding or milling PCCP to restore
rideabi 1ity
• Removal and replacement of the entire
pavement structure
9-7
Matching Condition Assessment and Strategy
The overall rating, actual distresses and their causes, and performance
of the surface over time should be analyzed to determine the most appropriate
•
strategy. A strategy should be thought of as an overall approach at this
point rather than specific decisions about where to patch or how many inches
of overlay to apply.
EXHIBIT 9-5
MAINTENANCE AND REHABILITATION STRATEGIES
A. ROUTINE
MAINTENANCE
100
90
B. PREVENTIVE
MAINTENANCE
.....
r-~-~-~-~-~-~-~-~-~-~-~-~-~--
1-+-1f----'~
C. DE FER
ACTION
80
D. REHABILITATION
70
o
•
E. RECONSTRUCTION
60
Q.
50
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 40
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 30
-------------------------------------20
10
YEARS
9-8
•
. vI
•
JAIi'v
1~~~~
rr V\
r. l
~
k
Exhibit 9-6
MAINTENANCE AND REHABILITATION
STRATEGY SELECTION
PC I
Other Considerations
76-95
None
A
61-75
Normal or Small Amount
of Surface Distress
Mostly Surface Distress
A
51-60
•
r
r4'"
41-50
26-40
0-25
Strategy
B
Mostly Surface Distress
Distress Evenly Balanced
Mostly Structural Distress or
very Rough (PSI < 2.0)
Relatively Smooth (PSI
Rough (PSI ~ 2.5)
~
2.5)
C
o
C
o
Relatively Smooth to Rough (PSI~ 2.0)
Very Rough (PSI ~ 2.0)
E
None
E
Strategy Keys:
A ­ Routine Maintenance
B ­ Preventive Maintenance
C ­ Deferred Action
D ­ Rehabilitation
E ­ Reconstruction
•
B
9-9
o
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Elements of Fiscal Policy
Many elements of society have encountered severe problems in meeting
financial obligations.
Local governments are no exception.
Long-standing
financing practices are often not adequate to meet today's needs and this is
particularly true in regard to local roads. In developing roadway programs,
however, it is helpful to remember some basic principles of roadway finance
which have stood the test of time. A sound roadway finance policy should:
•
Assess roadway needs clearly
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Provide budget amounts that are adequate and affordable
•
Involve the public in defining needs, funding levels, and taxes
•
Provide funding levels that are predictable
•
Maintain or establish an equitable tax structure
•
Be simple to administer and easy to understand
•
Estimates of expenditures are critical to the development of policy and
program contents for the current and future fiscal years.
Crucial to that
development is a projection of current trends to establish future needs.
It
is essential that the level and quantity of work output for a given fiscal
year be developed to provide a solid financial planning base.
Detailed work
plans will serve to place long-term plan components within a budgeting year
framework.
Capital investments must be programmed for implementation. It is
increasingly important for a capital program to consist of a systematically
prioritized group of projects. This helps insure that the scarce dollars are
used effectively in meeting public needs.
9-10
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•
Goals and Objectives
The logical sequence in establishing a plan for roadway maintenance and
capital improvement investments is to first decide upon long-range goals and
i
objectives, develop a program to reach those objectives (usually for 5-years),
and finally begin implementation of that program with the upcoming annual
!
budget.
Without the first step of clearly deciding where the local government
wi~hes to be in 10 or 20 years, annual road maintenance and capital
improvement programs are unlikely to be particularly beneficial in the long
ru~.
The establishment of goals and objectives is properly a political
pr~cess that should include the full participation of the public. Public
input not only reveals specific needs and areas of concern but will also help
I
ensure
support for the adopted program.
Many communities have master plans that have established general
lorlg-range goals and objectives. Specific transportation plans may also
ex'st, along with land-use plans. Goals and objectives for road surfaces
I
sh~uld be established within the overall frame-work of these more general
pl~ns.
The integration of these two concerns has at least two positive side
ef~ects:
• Those concerned with the condition and maintenance of road surfaces
will become better acquainted with overall transportation needs and
plans and can better anticipate impacts on their operations.
• Planners will become more sensitive to the impacts of large capital
improvement programs on operations and maintenance.
Road surface goals and objectives can take many forms.
Some examples are:
• Pave all roads with ADT's in excess of 100 vpd.
•
• Within 5-years raise the average PCI of the network to the following
levels:
- Arterials
- 70
Collectors
- 65
Local Access
- 60
9-11
• Lengthen the period between surface treatments from five years to
seven years, without lowering the level of condition.
• Lower the portion of the surface maintenance budget for unplanned,
emergency maintenance to 20 percent.
•
Clearly stated, achievable, long-range goals and objectives help to keep
programs and budgets in focus, for all members of an organization, as well as
managers. Goals and objectives that have been adopted by an elected board
also make it easier to justify funding programs that have been developed to
achieve those goals and objectives.
Determining Network Needs
There are three general approaches to determining overall pavement needs,
in terms of dollars. Regardless of the approach taken it is important to
associate costs to goals and objectives. If this can be done with some degree
of creditability managers will find program and budget approval much easier.
Each of the three approaches are discussed below, from the most simple to the
most complete:
•
Historical Trends - In the absence of inventory and condition data, local
governments can review expenditures for various strategies over a period of
time (say five to ten years) and relate these expenditures against a
subjective evaluation of the condition of the road surfaces. This is the
procedure that local governments must use in the absence of a more formal
procedure. Although this procedure may appear rather crude it can be refined
and made very useful for very small networks. The key to successful use of
this procedure is to document the condition of the network so performance can
be tracked over time. This allows for an evaluation of the effectiveness of
funding levels so the projections and needs can be determined.
Frequency of Activity - This procedure uses the average life of certain
activities, average costs, and the network inventory to arrive at total
network needs in terms of average annual investments. Perhaps the best way to
describe this process is a simple example. A rural county has 48 miles of
9-12
•
•
bituminous surface treated (SST) roads. If the average cost of the SST is
$7l200 per mile of 2-lane road and SST lasts an average of six years, then the
avkrage annual network need would be:
I
(48)(7,200) = $57,600
6
Si~ilar
evaluations would be needed for other surface types and treatments.
I Systematic Approach - The frequency method is very helpful in arriving at
•
•
aVfrage investment requirements but does not take into account actual
COpdition nor needed changes in strategies. In fact, some of the roads in the
abfve example may be performing very well and will need a treatment only every
ei~ht years.
Others may be failing after two years and infact should be
reyonstructed with a more substantial pavement structure.
The most complete way to arrive at total network needs is to assess
co6dition and assign strategies to each section, as discussed in Chapters 7,
8,l and 9, then apply average unit costs to each strategy and area. The result
Of!this process will be the total current network needs, using the most
ap~ropriate strategies to fit current conditions.
I A systematic approach can use portions of the two procedures discussed
earlier to help arrive at network needs and long-range goals and objectives.
Foh instance, if records are kept of levels of investments along with average
patement condition measurements as a result of distress surveys, then average
costs to raise the network condition can be developed. Also, expected
frJquencies
of activities can be used along with the currently assigned
I
I
strategy to help arrive at long-range needs.
At its most sophisticated, a systematic approach to network needs might
arrive
at an average network condition (say a PCI of 58) and a total current
I
neJd of $200,000 to raise the PCI to 80. Assuming that the total needs cannot
be funded immediately, it is possible to arrive at a target average condition,
th~ years it will take to arrive at that condition, and the average annual
I
in~estment needed to accomplish that objective.
Using our example, a
I
long-range goal might be to bring the network condition up to 75 within four
ye~rs with an average annual investment of $65,000. This type of analysis can
be idone subjectively using the best information available along with plenty of
i
engineering judgment, or it can be done quantitatively (which normally
I
reduires a computer).
9-13
Bibliography
•
Evaluation of Pavement Maintenance Strategies, NCHRP Synthesis 11,
Transportation Research Board, September 1981.
•
•
9-14
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