Analysis of Work Zone Crash Characteristics and Countermeasures (2018) / Chapter Skim
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Pages 36-45
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From page 36... ...
NCHRP Project 17-61 35 CHAPTER 3 Effects of Queuing and Crash Countermeasures at Interstate Work Zone Lane Closures Overview The analyses of the work zone crash datasets described in Chapter 2 verify the perceptions held by many practitioners that queues and congestion are a key contributor to rear-end collisions in work zones, especially on high-speed facilities such as freeways and interstates. Meanwhile, as noted in Chapter 2, multiple studies have shown rear-end collisions to be the predominant type of crash occurring in work zones, and often the type of crash that increases most significantly when a work zone is installed on a roadway segment.
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From page 37... ...
NCHRP Project 17-61 36 Methodology Description of the Study Corridor The Interstate 35 (I-35) Central Texas Expansion Project is a seven year, $2.1 billion highway expansion project currently underway along 96 miles within the Waco District, located between Austin and Dallas.
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From page 38... ...
NCHRP Pr F oject 17-61 igure 10. Conceptual operation of the 37 portable queue warning system.
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From page 39... ...
NCHRP Pr Figure 11 Descript Since 2 the corrid expected since the queue wa portable E of potenti nighttime data, for w over 400 closures w Determin Queuin Bluetooth Bluetooth likewise a that vehic used to de Each o Bluetooth segments upstream. assess wh oject 17-61 .
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From page 40... ...
NCHRP Pr developed travel tim minute tim present at average tr consecutiv lane closu 5-10 mph times wou magnitude closure m speeds thr The ho were then lane closu analysis f hours w hours w hours w hours w hours w hours w Figure 12 closure s oject 17-61 . If it had, th es over the a e intervals)
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From page 41... ...
NCHRP Project 17-61 40 Generally speaking, queues only developed for a portion of the nighttime lane closures when queuing did occur, and for many of the nights, no queues at developed at the lane closures. As a result, the dataset was heavily weighted towards non-queuing hours.
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From page 42... ...
NCHRP Pr Figure 13 Result As show deployed Likewise, than the n TxDOT a when the given nigh dataset fo conditions Table 6 in each c occurring during ho whereas th present. T crashes du zone or la what wou closures h work zon deployed the no sa EC w EC Se mod X oject 17-61 .
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From page 43... ...
NCHRP Project 17-61 42 crashes were 277% higher than would have been expected if no work zone or lane closure had occurred. During queued conditions when EOQWS & PRS were deployed, actual crashes were 331% higher.
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From page 44... ...
NCHRP Project 17-61 43 was present, both treatments yielded significant reductions in crashes relative to what would have been expected had the treatments not been deployed. Interestingly, the PRS only treatment achieved essentially the same crash reduction as the EOQWS and PRS combined, yielding 60.3% and 53.2% reductions in crashes, respectively.
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From page 45... ...
NCHRP Pr these cons (if any) to Figure 14 queuing.
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