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48 Improve coordination, planning, and scheduling of work a direct cause-effect analysis of crash cost reductions is not activities; possible. Use incentives to create and operate safer work zones; and Implement work zone quality assurance procedures Summary (i.e., safety inspections or audits). The information presented in this chapter provides some Work zone crash data systems are addressed in detail in insight into the magnitude of benefits possible by imple- the next chapter. The improvement of coordination, plan- menting some of the strategies listed in the NCHRP guid- ning, and scheduling of work activity strategy refers to ance document. Table 21 summarizes the results of this efforts to coordinate multiple agencies that may be affected assessment. Overall, strategies that reduce overall work by a particular project as well as to coordinate multiple proj- zone frequency and duration either indirectly or through ects in a region that may interact with each other from a accelerated contracting mechanisms appear capable of traffic perspective (52). This type of coordination is believed yielding substantial safety benefits. Likewise, efforts to re- to reduce the frequency and significance of traffic congestion duce overall traffic demands through work zones by way that may be created by work zones and thus, has a potential of trip reductions and mode choice changes have the safety benefit. However, the NCHRP document does recog- potential to provide substantial safety benefits (although nize that attempting to quantify the relationship between achieving even small reductions may be difficult in some this type of strategy and actual safety benefits would not be locations). Decisions to work at night now being made by feasible. Similarly, incentives to create and operate safer many agencies, although primarily a congestion mitigation work zones are also viewed as a way of raising awareness of strategy, can also be shown to yield crash cost reductions safety issues and ensuring that safety is constantly consid- when compared to doing the same work during daytime ered by agency and contractor personnel; however, data do hours. Finally, the provision of law enforcement in work not exist to allow assessment of the strategy upon work zone zones appears to be capable of yielding crash cost reduction crash costs. benefits that offset the cost of providing such enforcement The final strategy, implement work zone quality assur- in most situations. ance procedures, refers to the use of periodic inspections of In addition to these high-return strategies, there also ap- work zone traffic control and other features to ensure that pear to be a number of strategies that provide moderate crash they are installed and operating as intended throughout the cost reductions when applied. These include full roadway duration of each project (52). Several states conduct regular closures (this strategy may be particularly effective if median inspections of their work zones, both by personnel assigned crossovers and detours onto adjacent frontage roads are to the project (i.e., inspectors) as well as those not affiliated included), the design of future work zone capacity into high- with the day-to-day operations of the work zone (i.e., a dis- ways, and possibly the application of ITS strategies at work trict or division quality review team). In order for this tech- zones that are likely to experience frequent but unexpected nique to be effective, it must consider how the temporary bouts of congestion created by work zone activities. For work traffic control is functioning as a system from the user's per- zones of significant duration on high-volume roadways, meth- spective (i.e., is it providing clear and unambiguous path ods that protect against vehicle intrusions into the workspace guidance, etc.), not just whether the devices are present as (i.e., portable concrete barrier) may fall into this category called for in the traffic control plan (52). This strategy also as well. refers to the use of work zone safety audits, similar to road Relative to those strategies already listed, there are several safety audits, as a way to identify potential contributors to strategies in the guidance document for which the potential work zone crashes and ways to modify the work zone so as impact on crash costs is more limited. In many instances, the to mitigate those crashes as much as possible. The idea of frequency of crashes that the strategy is intended to target is work zone safety audits being performed before and during relatively small. Intrusion crashes on relatively short-duration a work zone project is fairly new. Guidance is currently projects would be one such example. Whereas intrusion pro- being developed as part of the previously mentioned FHWA tection on long-term projects on high-volume roadways Work Zone Safety Grant program (70). As with the other may ultimately be justifiable using portable concrete barri- strategies in this category, the ability to directly link efforts ers (as the per-hour cost of the countermeasure decreases of either inspections or audits to actual crash cost reduc- over time), other strategies to address more short-duration tions is quite limited. Anecdotal information implies a cor- situations have the potential to impact only a small portion relation between a systematic and regular application of of crash costs overall. Still, such strategies may be justified in these types of activities and reduced crash frequencies, but certain situations where risks are extremely high (such as

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49 Table 21. Potential effectiveness of agency strategies to improve work zone safety. Strategies Work Zone Potential Key Considerations Conditions Impact on Influenced Crash Costs Practices to Reduce Work Zone Duration All work zone High One of the most effective strategies available to reduce work zone crash and Number of Work Zones Required conditions costs. Full Roadway Closures All work zone Moderate-high Crash cost reductions in work zone may be offset by crash cost increases conditions on alternative routes if crash rates on alternative routes are substantially higher than that on the work zone route. Time-Related Contract Provisions to All work zone High Similar in effectiveness to first strategy listed in this table. Reduce Construction Duration conditions Moving Work Activities to Nighttime Active work zones High The effectiveness of this strategy in reducing work zone crash costs Hours with temporary increases exponentially at higher AADTs. lane closures Demand Management Programs to All work zone High Crash cost reductions in a work zone can be high if trips are reduced or Reduce Volumes through Work Zones conditions eliminated. If trips are simply diverted, crash cost reductions may be offset by higher crash rates on diversion routes. Designing Adequate Future Work Zone All work zone Moderate Similar crash cost reductions can be achieved by shifting work to Capacity into Highways conditions nighttime hours if lanes need to be temporarily closed. Improvement of Work Zone Traffic All work zone Low-moderate Crash cost reductions achieved only if current agency policies and Control Device Visibility conditions processes for ensuring quality devices are lacking. Improvement of Work Zone Personnel Active work zones Low Low frequency of these types of crashes. and Vehicle Visibility Reductions in Flaggers' Exposure to Active work zones Low-moderate Low frequency of these types of crashes. Traffic ITS Strategies to Improve Safety Active work zones Moderate Effectiveness depends on frequency of unexpected congestion that is created in work zone. Improvements in Work Zone Design All work zone Unknown Dependent upon design features to be improved. Guidance conditions Improvements for Pedestrians, Bicyclists, All work zone Unknown Data not available regarding effects of strategies on these user groups. Motorcyclists, and Heavy-Truck Drivers conditions Measures to Reduce Workspace All work zone Low-moderate Low frequency of these types of events limits the amount of crash cost Intrusions and Limit Consequences conditions reduction that can be achieved. Those that result in a worker being hit will be very severe and costly, however. Improved Credibility of Signs All work zone Unknown Data not available regarding effects of strategies on crash costs. conditions Enhanced Traffic Law Enforcement All work zone High Effectiveness dependent upon amount of enforcement presence applied. conditions Improved application of increased driver All Work Zone Low Higher penalties have not been shown to dramatically affect driver penalties in work zones Conditions behavior. Dissemination of work zone safety All Work Zone Unknown Effectiveness likely depends on extent of work zone safety information information to road users Conditions already being disseminated by agency. Work zone training programs and All Work Zone Unknown Effectiveness likely depends heavily on whether current agency training manuals for designers and field staff Conditions programs and tools are already of high quality and available. Develop/enhance agency-level work zone All Work Zone Unknown Effectiveness depends on whether analysis of the crash data leads to crash data systems Conditions changes in policies, procedures, and/or design criteria. Improved coordination, planning, and Primarily Active Unknown Reductions in total frequency and duration of work zones would yield scheduling of work activities Work Zones crash cost reductions similar to those listed in first and third strategies in this table. Incentives to create and operate safer All Work Zone Unknown Data not available regarding effects of strategies on crash costs. work zones Conditions Work zone quality assurance procedures All Work Zone Unknown Effectiveness depends heavily on whether current agency policies and (i.e., safety inspections or audits) Conditions procedures result in high-quality work zones already. during a bridge rail repair activity where workers have no Finally, the likely impacts of some strategies on crash costs reasonable escape route in the unlikely event that a vehicle cannot be assessed at this time. In most cases, the relation be- intrusion occurs). In those situations, though, the agency tween these types of strategies and crash cost reductions is and contractor are generally paying a premium to provide likely to be indirect. Consequently, the adoption of one or protection in excess of the likely reduction in crash costs to more of these strategies is likely to be based on factors other be achieved. than crash cost potential at individual work zones.