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37 work activity with or without temporary lane closures is ap- Accelerated Contract Provisions proximately $5,000. Conversely, the reduction of 100 hours of work activity on a roadway with an AADT of 250,000 vpd Previously, it was noted that efforts to reduce work zone would yield a $21,000 reduction in crash costs, based on the duration through accelerated construction techniques typi- values shown in Figure 16. cally increase project costs to some degree. The savings in crash costs associated with these techniques can partially off- set those project cost increases. However, it is typically up to Full-Time Roadway Closures the contractor to determine the magnitude of the additional When and where it is possible to do so, completely closing costs and how to best adjust the bid price to account for those a roadway section to allow construction or maintenance work costs. Another approach that agencies can take to accelerate to be performed eliminates the potential for traffic crashes to the work is to include time-related contract provisions that occur in the activity area (52). In addition, the elimination of provide incentives for completing the work faster (or disin- interactions between construction vehicles/equipment and centives if the work is not completed fast enough) and traffic often allows for larger workspaces and increased encourage the use of non-peak times for any temporary lane worker productivity, thus reducing the total duration of the closures that are required. Specific techniques that fall under work activity. It is possible that work quality can be improved this particular strategy include the following: as well. Closing one direction of a freeway and putting both directions of traffic on the other directional roadway via Cost-plus-time (also known as A+B) bidding, median crossovers is one example of this strategy. Likewise, Lane rentals, closing one direction and moving traffic onto the adjacent Incentive/disincentive clauses, and frontage road around the work zone is another example. Liquidated damages clauses. However, this strategy can entail the complete closure of both travel directions and detouring of traffic onto completely A number of resources are available that discuss these tech- different roadways in the region. niques in detail, which have been identified in the NCHRP The various factors that need to be considered before im- guidance (54). plementing a full-roadway closure (i.e., availability and ac- Traditionally, justification of these techniques and the values ceptability of detour routes; provision of adequate advance assigned to them have been made on the basis of potential notification to residents, businesses, and regular users of the travel time delays, which alone can result in large additional facility; etc.) are documented elsewhere (52). From a safety road user costs. From the perspective of safety, however, the assessment perspective, the amount by which traffic crashes ramifications of accelerating construction through the use of in the work zone is reduced can be significant since both the time-related contract provisions do provide some additional additional crash costs due to the work zone and the crashes benefit, identical to those described previously in the normally occurring on that roadway segment are eliminated. "Improvements in Maintenance and Construction Practices" However, these reductions in crash costs may be offset to some section. These values could be added to other costs (i.e., delay degree by an increase in crash costs on the detour route(s) due or deferred usage costs) typically considered in the overall de- to the additional traffic exposure that is placed on each route. termination of the values assigned to these techniques in a Whereas this is not likely to be a significant concern when construction or maintenance contract. median crossovers or frontage road detours are employed, it may be more important if traffic is being completely detoured Nighttime Work off of a freeway-type facility onto arterials and other surface streets. Normally, crashes occur more frequently on arterial The decision whether work must be performed at night streets than on freeways but are less severe. Consequently, a should involve a comprehensive cost-effectiveness evalua- detailed analysis of a particular site and the feasible alternative tion that should consider the implications of each alternative routes would be required to assess whether there is a net crash (including active night work) with respect to three key impact cost benefit to a full roadway closure. Estimating the addi- factors: tional crash costs on these detour routes requires information on how much additional traffic is being carried on each route, Impact to the community and traffic (business operations, the normal traffic volumes on those routes, and the SPF(s) for pedestrians and bicyclists, emissions, public transit, emer- each route (recognizing that the SPF for each route may vary gency services, noise effects, lighting and glare effects, traffic depending on the number and type of intersections, frequency diversion impacts, etc.); and use of driveways, etc.). These were not available for any of Impact on safety (construction safety, traffic safety, and the projects used in this database. safety during maintenance efforts); and