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Pages 34-49

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From page 34... ... The specific strategies are organized under the following objectives: • Reduce the number, duration, and impact of work zones, • Improve work zone traffic control devices, • Improve work zone design practices, • Improve driver compliance with work zone traffic controls, • Increase knowledge and awareness of work zones, and • Develop procedures to effectively manage work zones. The critique in that report included an assessment of the following considerations for each strategy under those objectives: • Types of work zone crashes targeted; • Expected effectiveness; • Keys to success; • Potential difficulties; • Appropriate measures and data and associated needs; • Organizational, institutional, and policy issues; • Implementation time considerations; • Costs; • Training and other personnel needs; • Legislative needs; and • Compatibility with other strategies. Read the entire page →
From page 35... ... In contrast, techniques that reduce the frequency and duration of work activity have a greater potential to reduce crash costs. At work zones on very low-volume roadways, a technique that reduces 100 hours of work activity without temporary lane closures would yield a crash cost reduction of about $5,000 ($600 per daytime period) Read the entire page →
From page 36... ... At roadway AADTs of about 25,000 vpd, the reduction of 100 hours of nighttime 36 $0 $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 0 50000 100000 150000 200000 250000 Roadway AADT A dd iti on al C ra sh C os ts p er 1 00 H ou rs p er M ile Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive Figure 15. Effect of strategies to reduce work zone frequency and duration: daytime conditions. Read the entire page →
From page 37... ... . From a safety assessment perspective, the amount by which traffic crashes in the work zone is reduced can be significant since both the additional crash costs due to the work zone and the crashes normally occurring on that roadway segment are eliminated. Read the entire page →
From page 38... ... Based on the data from this study, fairly significant reductions in crash costs can be achieved through fairly moderate reductions in trips in a work zone corridor due to TDM 38 -$5,000 $0 $5,000 $10,000 $15,000 $20,000 $25,000 $30,000 $35,000 $40,000 $45,000 0 50000 100000 150000 200000 250000 Roadway AADT Sa vi ng s in C ra sh C os ts p er 1 00 H ou rs p er M ile With Temporary Lane Closures Without Temporary Lane Closures Figure 17. Example of reduction in crash costs achieved by working at night. Read the entire page →
From page 39... ... If the latter 39 $0 $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 0 50000 100000 150000 200000 250000 Roadway AADT R ed uc tio n in C ra sh C os ts p er 10 0 Ho ur s pe r M ile 10% TDM Reduction - Daytime 10% TDM Reduction - Nighttime 20% TDM Reduction - Daytime 20% TDM Reduction - Nighttime Figure 18. Example of reduction in crash costs by travel demand management strategies during work activity with temporary lane closures. Read the entire page →
From page 40... ... As the graph indicates, if an agency is willing to do work at night that requires temporary lane closures, the safety benefits associated with roadway designs that reduce the number of lane closures that are required will be fairly negligible, regardless of the AADT of the roadway segment. In other words, an emphasis on design enhancements that reduce the frequency and duration of work zones has more of a potential safety benefit than enhancements that reduce the number of work hours that travel lanes need to be closed. Read the entire page →
From page 41... ... Reduction in crash costs by avoiding daytime lane closures through roadway design enhancements versus closing lanes at night. Read the entire page →
From page 42... ... At night, the values range from as little as $500 per 100 hours per mile at 5,000 vpd up to approximately $3,000 per 100 hours 42 $0 $5,000 $10,000 $15,000 0 50000 100000 150000 200000 250000 Roadway AADT R ed uc tio n in R ea r-E nd a nd Si de sw ip e Cr as h Co st s pe r 10 0 Ho ur s pe r M ile Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive $0 $5,000 $10,000 $15,000 0 50000 100000 150000 200000 250000 Roadway AADT R ed uc tio n in R ea r-E nd a nd Si de sw ip e Cr as h Co st s pe r 10 0 Ho ur s pe r M ile Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive Figure 22. Estimated reduction in crash costs due to a 10 percent reduction in rear-end and sideswipe collisions: daytime conditions. Read the entire page →
From page 43... ... As was noted from the NYSDOT crash data analysis reported in Table 4, intrusion crashes comprise a relatively small subset of freeway work zone crashes during temporary lane closures (9.8 percent of those occurring during the day and 14.4 percent of those occurring at night) Read the entire page →
From page 44... ... Further research is needed to determine the costs of some of these intrusion 44 $0 $5,000 $10,000 $15,000 0 50000 100000 150000 200000 250000 Roadway AADT Cr as h Co st s du e to V eh ic le In tr us io ns p er 1 00 H ou rs p er M ile Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive Figure 24. Estimated crash costs due to vehicle intrusions: daytime conditions. Read the entire page →
From page 45... ... The NCHRP guidance document lists the following three specific strategies under this category that are believed to positively influence work zone safety: • Improved credibility of signs, • Enhanced enforcement of traffic laws in work zones, and • Improved application of increased driver penalties in work zones. The first strategy, improving the credibility of signs, emphasizes the importance of ensuring that the posted signing in work zones meets current federal and state standards and reflects actual conditions in the work zone. Read the entire page →
From page 46... ... . At the lower end of the pay scale, it appears that enforcement can be economically justified under all work 46 Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive $0 $2,500 $5,000 $7,500 $10,000 $12,500 $15,000 0 50000 100000 150000 200000 250000 Roadway AADT R ed uc tio n in C ra sh C os ts p er 1 00 H ou rs p er M ile 25% Reduction in Crashes 10% Reduction in Crashes Work Zone Active with Temporary Lane Closures Work Zone Active without Temporary Lane Closures Work Zone Inactive $0 $2,500 $5,000 $7,500 $10,000 $12,500 $15,000 0 50000 100000 150000 200000 250000 Roadway AADT R ed uc tio n in C ra sh C os ts p er 1 00 H ou rs p er M ile 25% Reduction in Crashes 10% Reduction in Crashes Figure 27. Read the entire page →
From page 47... ... Conversely, if crash cost reductions of 25 percent are achieved, use of enforcement at this cost level is justifiable at all AADT levels during the day and once AADT levels exceed about 50,000 vpd, if the work activity and temporary lane closures are done at night. The third strategy in this category, improved application of increased driver penalties in work zones, is predicated on the notion that higher penalties consistently applied to violators of traffic laws in work zones will change driving behavior and yield a reduction in work zone crash costs. Read the entire page →
From page 48... ... However, the NCHRP document does recognize that attempting to quantify the relationship between this type of strategy and actual safety benefits would not be feasible. Similarly, incentives to create and operate safer work zones are also viewed as a way of raising awareness of safety issues and ensuring that safety is constantly considered by agency and contractor personnel; however, data do not exist to allow assessment of the strategy upon work zone crash costs. Read the entire page →
From page 49... ... Moving Work Activities to Nighttim e Hours Active work zones with temporary lane closures High The effectiveness of this strategy in reducing work zone crash costs increases exponentially at higher AADTs. Dem and Managem ent Programs to Reduce Volumes through Work Zones All work zone conditions High Crash cost reductions in a work zone can be high if trips are reduced or eliminated. Read the entire page →

From page 34...

... The specific strategies are organized under the following objectives: • Reduce the number, duration, and impact of work zones, • Improve work zone traffic control devices, • Improve work zone design practices, • Improve driver compliance with work zone traffic controls, • Increase knowledge and awareness of work zones, and • Develop procedures to effectively manage work zones. The critique in that report included an assessment of the following considerations for each strategy under those objectives: • Types of work zone crashes targeted; • Expected effectiveness; • Keys to success; • Potential difficulties; • Appropriate measures and data and associated needs; • Organizational, institutional, and policy issues; • Implementation time considerations; • Costs; • Training and other personnel needs; • Legislative needs; and • Compatibility with other strategies.