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OCR for page 45
45
$2,000
Involved Vehicle Intrusions per 100
Crash Costs due to Worker-
$1,500
Hours per Mile
$1,000
$500
$0
0 50000 100000 150000 200000 250000
Roadway AADT
Daytime Conditions Nighttime Conditions
Figure 26. Estimated costs of worker-involved vehicle
intrusion crashes during work activities involving temporary
lane closures.
countermeasure ideas, as well as to estimate the expected crash have limited opportunity to further improve conditions or
reductions that may be achieved by the countermeasures. safety through this strategy. In contrast, agencies whose poli-
cies, standards, and procedures are lacking would have the
potential to improve conditions and achieve measurable
Strategies to Improve Driver
safety benefits. In reality, differences between agencies may
Compliance with Work Zone
be much more subtle, with examples of both good and not-
Traffic Controls
so-good work zone implementations evident in either juris-
Good compliance with traffic laws and regulations in work diction. One could hypothesize that the higher rear-end crash
zones is critical to obtaining and maintaining a high level of percentages cited in the previous chapter are one way in
safety and orderly, efficient traffic flow. The NCHRP guid- which a lack of sign credibility manifests itself, leading to
ance document lists the following three specific strategies higher levels of inattentive or unsuspecting drivers who dis-
under this category that are believed to positively influence regard the advance warning signs of a work zone.
work zone safety: The remaining two strategies in this category both relate
to the effectiveness of law enforcement to ensure driver com-
· Improved credibility of signs, pliance with traffic laws and regulations in the work zone.
· Enhanced enforcement of traffic laws in work zones, and Essentially all states utilize law enforcement personnel in some
· Improved application of increased driver penalties in work fashion in their work zones (55). However, the manner in which
zones. enforcement personnel are used varies. Some agencies empha-
size the use of enforcement for active identification of violators
The first strategy, improving the credibility of signs, em- and issuance of citations in the work zone, whereas others
phasizes the importance of ensuring that the posted signing emphasize the use of enforcement presence for visibility and
in work zones meets current federal and state standards and attention-getting purposes during times when workers are out
reflects actual conditions in the work zone. Efforts to ensure in travel lanes at high risk next to moving traffic (55). Currently,
that the information presented via static and dynamic signing there is little objective evidence to suggest which approach is
is as accurate and as current as possible at all times is also more effective in promoting safety, although an ongoing
believed to result in improved driver compliance and, ulti- NCHRP project is examining this issue in more detail (56).
mately, work zone safety (52). Although this statement is in- Overall, there is some evidence to suggest that additional
tuitively obvious, the extent to which these efforts can be enforcement presence in both work zones and non-work
quantified in terms of potential work zone crash reductions zone locations can improve safety (57, 58, 59, 60). However,
or improvements is limited. Theoretically, agencies with good the amount of the improvement from a crash reduction per-
policies and standards in place as well as effective procedures spective varies due to differences in enforcement strategies
to monitor and quickly correct deficiencies in the field would used, the amount of additional enforcement used, and the
OCR for page 46
46
$15,000
Reduction in Crash Costs per 100
25% Reduction
in Crashes
$12,500
Hours per Mile
$10,000
$7,500
$5,000
$2,500 10% Reduction
in Crashes
$0
0 50000 100000 150000 200000 250000
Roadway AADT
Work Zone Active with Temporary Lane Closures
Work Zone Active without Temporary Lane Closures
Work Zone Inactive
Figure 27. Possible reductions in crash costs due
to enforcement presence: daytime conditions.
type of crash analysis used, making comparisons across studies expected to influence the potential of all crashes to occur.
difficult. Conservatively, crash reductions of up to 25 percent Both a 25 percent reduction and an even more conservative
in the vicinity of enforcement may be possible. If reductions 10 percent crash cost reduction are shown.
of this magnitude are achieved, the question becomes whether A review of some recent memorandums of understanding
the costs of providing that enforcement are outweighed by (MOUs) between highway and enforcement agencies to pro-
the reduction in crash costs that occur. Depending on the vide work zone enforcement support indicates hourly costs
characteristics of the work zone, the answer appears to be yes. of between $25 and $60 per hour per officer (between $2,500
Using the California crash models again for illustrative pur- and $6,000 per 100 hours). The costs may be higher in other
poses, Figure 27 and Figure 28 present the crash cost savings states. These costs can be compared to the crash cost savings
that would be achieved under the various work conditions estimated in the figures to determine the AADT level at which
during daytime and nighttime periods. Total crash costs, not the savings begin to exceed these costs (for a work zone 1 mile
just the additional crash costs due to work zone presence, are in length). At the lower end of the pay scale, it appears that
used in the analysis because enforcement presence would be enforcement can be economically justified under all work
$15,000
Reduction in Crash Costs per 100
$12,500
Hours per Mile
$10,000
25% Reduction
in Crashes
$7,500
$5,000
$2,500
10% Reduction
in Crashes
$0
0 50000 100000 150000 200000 250000
Roadway AADT
Work Zone Active with Temporary Lane Closures
Work Zone Active without Temporary Lane Closures
Work Zone Inactive
Figure 28. Possible reductions in crash costs due
to enforcement presence: nighttime conditions.
