Work Zone Speed Management (2015) / Chapter Skim
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Pages 7-19
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7 PROBLEM STATEMENT SUMMARY AND SCOPE OF THIS SYNTHESIS REPORT This Synthesis of Practice focuses on speed management for work zones on roadways with ordinary (preconstruction) speed limits of 45 mph (70 km/h)
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8 Appropriate institutional arrangements are required for implementation of work zone speed management techniques and can be particularly challenging for some of the enforcement-related techniques discussed in chapter six. As Hyman has noted (2012)
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9 • When conditions become unstable average speeds may decline sharply, but crash rates may increase as a result of abrupt fluctuations in the running speed. It is also important to recognize that some speed reduction techniques can reduce average running speeds while increasing speed variation (differences between the fastest and slowest vehicles)
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10 mation presented to the driver. At higher speeds drivers do not have time to process all of the information that is being gathered visually; the human brain compensates by analyzing only the central part of the image (OECD 2006)
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11 caused by the road work extend upstream of the signs. The accuracy of the information reported by law enforcement on the "check the box" sections of crash report forms has also been questioned; for example, comparison of detailed Illinois crash narratives with statistical crash abstracts found that 65% of work zone crashes were miscoded (Raub et al.
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12 limits of the temporary traffic control zone [as defined by the U.S. Manual on Uniform Traffic Control Devices (MUTCD)
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13 stepped up immediately. In September 2012, the RCMP launched a provincewide safety blitz to catch speeders in construction zones, which involved officers dressed as construction workers observing drivers in the work zone and communicating with downstream officers to intercept speeders.
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14 time a driver exceeds the speed limit without apparent consequences. • Although speed is a factor in a very high percentage of serious and fatal crashes, many drivers underestimate these risks.
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15 major wrong by exceeding the work zone speed limit (Bolling and Nilsson 2001)
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16 if there are merges within the Activity Area. Multiplevehicle involvement can be high because of a lack of escape routes (especially if lane width is constrained by temporary concrete barriers)
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17 The location where speeds are measured is another consideration: some speed management measures have only a localized effect, while others are effective over a longer distance. When comparing the results of work zone speed studies it is also necessary to consider the observational methods and equipment used to compute the speeds.
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18 of the speed and axle spacing calculations (owing to the decrease in the significance of any error in tube length or tube spacing) " (Mendigorin et al.
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19 Finally, it is necessary to note that some of the speed management techniques included in this synthesis report have been tested only on a limited basis (e.g., small sample size, small number of sites, limited diversity of sites) , resulting in some uncertainty.
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