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costs are primarily comprised of the costs of human fatali- computations. A somewhat simplified approach for comput-
ties, nonfatal injuries, and accompanying property damage. ing work zone time-delay costs is presented in NCHRP Report
· Discomfort costs. Costs associated with driving in congested 523 (Peshkin et al. 2004). The OPTime spreadsheet program
traffic or on rough roads. developed as part of that study on optimal timing of preventive
· Environmental costs. Costs associated with traffic noise and maintenance can be used to perform the computations. Fol-
with the operation of construction equipment in work zones. lowing are brief descriptions of how user costs can be incorpo-
rated into the EAC and BCR methods of cost-effectiveness
Additionally, user costs can be incurred during the estab- analysis:
lishment of a work zone or during normal (nonrestricted)
highway operating conditions: · In the EAC method, two aspects of user costs can be con-
sidered. The first aspect is the work zone user costs asso-
· Work zone costs. This category of user costs deals with costs ciated with each alternative preservation treatment.
brought about by the establishment of a work zone. A work Since the work zone characteristics of each alternative
zone is defined as an area of a highway where maintenance, will vary based on application rates, material setting/
rehabilitation, or construction operations are taking place, curing times, and other construction factors, the delays
which impinge on the number of lanes available to mov- experienced as a result of the different work zone require-
ing traffic or affect the operational characteristics of traffic ments will also vary.
flowing through the area (Walls and Smith 1998). A work · The second aspect is the work zone user costs associated
zone disrupts normal traffic flow, drastically reduces the with the timing of an assumed future rehabilitation at the
capacity of the roadway, and leads to specific changes in end of the preservation treatment's expected life. A preser-
roadway use patterns that affect the nature of user costs. vation treatment with a longer forecasted life results in a
· Normal operating condition costs. In between work zone delay in the timing of the assumed rehabilitation. When
periods, user costs are still incurred during normal operat- discounted to present-day costs, the work zone user costs
ing conditions. These include highway user costs associated associated with the rehabilitation will be lower than the
with using a facility during periods free of construction, same rehabilitation work zone user costs associated with a
repair, rehabilitation, or any work zone activity that restricts shorter life-preservation treatment. This is illustrated in
the capacity of the facility. Figure 3.4.
· In the BCR method, the user costs of all future preserva-
The inclusion of user costs as part of any economic analysis tion and rehabilitation treatments associated with each
of pavements is a controversial issue. While there is general preservation strategy can be computed as part of the
agreement that traffic delays increase user costs, the actual LCCA. Although the user cost NPV results may be com-
costs can be difficult to quantify and often overwhelm the bined with the agency cost NPV results, it is generally rec-
direct agency costs, particularly for high-volume facilities ommended that they be examined separately because of
(Peshkin et al. 2004). the possibility that they will overwhelm the agency costs.
Current FHWA-recommended practice is to consider
including in the economic analysis only the time-delay and
Selection of the Preferred
vehicle operating cost components associated with work
Preservation Treatment
zones. These components can be estimated reasonably well
and make up a large portion of the total user costs. Other Although treatment cost-effectiveness is a major consideration
work zone user cost components are too difficult to collect or in the selection of the preferred treatment, it is not the final
reasonably quantify, or they do not factor to an appreciable answer in the process. The reality of the decision-making
amount. Furthermore, for most pavement facilities in fair or process is that many other factors (economic and noneco-
good condition (e.g., pavements with a PSR of 2.5 or greater), nomic) must be considered along with cost-effectiveness.
user costs during normal operating conditions are minimal Some of these factors may have been previously considered as
(Peshkin et al. 2004). part of the steps to identify feasible treatments, yet may also
For projects in which time-delay and VOC work zone user be desired for consideration in the final selection. Examples
costs are likely to occur as a result of performing preservation include the availability of qualified (and properly equipped)
and/or rehabilitation activities, consideration should be given contractors and quality materials, the anticipated level of traf-
to evaluating these costs as part of the selected cost-effectiveness fic disruption, and surface characteristics issues.
analysis method. Detailed procedures for computing them Upon completion of the cost-effectiveness analysis, it may
are provided in the FHWA's Interim Technical Bulletin on be desirable to eliminate certain treatment alternatives on the
LCCA in Pavement Design (Walls and Smith 1998), and the basis of not being able to meet key financial goals. Such elim-
RealCost spreadsheet program can be used to perform the ination criteria might include the following:
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Pavement
Condition
Preservation
Treatment 1
(PT1)
Preservation
Treatment 2
(PT2)
Condition Threshold
(Trigger for Rehabilitation)
LifePT2 LifePT1
Time, years
UCRehab UCRehab
Discount future
UCRehab user costs to
NPV present day
(PT2) UCRehab
NPV
(PT1)
TPT2 TPT1 Time, years
Figure 3.4. Effect of preservation treatment life on discounted rehabilitation
user costs.
· Substantially lower cost-effectiveness compared with that which can also be assigned weights as part of a decision
of other treatment alternatives (e.g., EAC greater than 10% matrix:
higher than the EACs of the alternatives, B/C ratios greater
than 10% less than the ratios of the alternatives); · Economic attributes:
· Initial cost greater than available funding, resulting in neg- Initial cost;
ative impact on network-level budgeting; and Cost-effectiveness (EAC or B/C);
· Excessive user costs that would have serious negative impact Agency cost; and
on roadway users. User cost.
· Construction/materials attributes:
Availability of qualified (and properly equipped) con-
Alternatively, these economic factors can be combined
tractors;
with several noneconomic factors, as described below.
Availability of quality materials;
A useful mechanism to systematically and rationally
Conservation of materials/energy; and
evaluate the different factors and identify the preferred
Weather limitations.
treatment is the treatment decision matrix. In a treatment
· Customer satisfaction attributes:
decision matrix, various selection factors are identified for
Traffic disruption;
consideration and each factor is assigned a weight. The
Safety issues (friction, splash/spray, reflectivity/visibil-
weights are then multiplied by rating scores given to each
ity); and
treatment alternative, based on how well the treatment sat-
Ride quality and noise issues.
isfies each of the selection factors. The weighted scores of · Agency policy/preference attributes:
each treatment alternative are then summed and compared Continuity of adjacent pavements;
with the weighted scores of the other treatments. The treat- Continuity of adjacent lanes; and
ment with the highest score is then recognized as the pre- Local preference.
ferred treatment.
A fairly complete list of factors that are appropriate for A decision matrix that incorporates these factors and illus-
inclusion in the final selection process is provided below. trates the assignment of weights and the basis for rating scores
The factors are grouped according to different attributes, is provided in Table 3.6.
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Table 3.6. Example of Preservation Treatment Decision Matrix
Treatment 1 Treatment 2
Attribute Factor Combined Rating Weighted Rating Weighted
Attribute and Selection Factor Weight Weight Weight Score Score Score Score
Economic 40
Initial cost 30 12.0
Cost-effectiveness 30 12.0
Agency cost 10 4.0
User cost 30 12.0
Total 100
Construction/materials 25
Availability of qualified contractors 20 5.0
Availability of quality materials 20 5.0
Conservation of materials/energy 30 7.5
Weather limitations 30 7.5
Total 100
Customer satisfaction 25
Traffic disruption 40 10.0
Safety issues 40 10.0
Ride quality and noise issues 20 5.0
Total 100
Agency policy/preference 10
Continuity of adjacent pavements 20 2.0
Continuity of adjacent lanes 20 2.0
Local preference 60 6.0
Total 100
Cumulative Weighted Score
Note: Basis for treatment rating scores (1-to-5 scale); initial cost: 1 = highest, 5=lowest; cost-effectiveness: 1 = least cost effective, 5 = most cost-effective; agency cost:
1 = highest, 5 = lowest; user cost: 1 = highest, 5 = lowest; availability of qualified contractors: 1 = low/none, 5 = high; availability of quality materials: 1 = low/none,
5 = high; conservation of materials/energy: 1 = low, 5 = high; weather limitations: 1 = major, 5 = low/none; traffic disruption: 1 = major, 5 = low/none; safety issues:
1 = serious, 5 = none; ride quality and noise issues: 1 = serious, 5 = none; continuity of adjacent pavements: 1 = does not match at either end, 5 = matches at both ends;
continuity of adjacent lanes: 1 = does not match, 5 = matches; local preference: 1 = inconsistent with preference, 5 = consistent with preference.
