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84 the dates and locations of all work zones. This file could be · Work zone fatal crashes are more common in the summer started considering only long-term construction projects on months than all fatal crashes. Interstates and state highways. · Almost 60 percent of work zone fatal crashes occurred on If results of this analysis show that most work zone fatalities roads with posted speed limits of 55 mph or greater. are occurring on Interstates, then crash reduction strategies · Work zone fatal crashes are more likely to involve more such as 19.1 A2-utilize full-time roadway closure for construc- than 2 vehicles than all fatal crashes. tion operations, or 19.1 F4-implement work zone quality assurance procedures could be implemented. This analysis is limited by the available data and many of If work zone crashes are concentrated in the daytime or the results from Exhibit X-4 could be related to exposure. In weekdays, Strategy 19.1 A4-use nighttime road work could be other words, more work zones occur in summer months and considered. Strategy 19.1 F2-improve coordination, planning therefore the proportion of work zone crashes is higher in and scheduling of work activities may also be effective in summer months than all crashes. work zone crash reduction. At this level, Strategy 19.1 F1-develop/enhance agency level If the percentage of pedestrian, bicyclists or motorcyclists work zone crash data systems should be considered. The ad- crashes is larger than for total crashes, then Strategy 19.1 dition of a highway inventory that is linked to crash data and C3-improve work zone safety for pedestrians, bicyclists and a work zone file that gives dates and locations of work zones motorcyclists should be considered. A large number of pedes- would enable a much more comprehensive analysis. trian crashes may also indicate worker crashes that are traffic If rear-end and multiple-vehicle crashes are more pre- crashes, as opposed to worker occupational injuries. This pat- dominant in work zones than for all crashes, Strategy 19.1 tern would point to Strategy 19.1 B4-reduce flagger exposure B2-improve visibility of work zone traffic control devices and to traffic, or Strategy 19.1 C2-implement measures to reduce Strategy 19.1 D2-improve credibility of signs should be im- work space intrusions and limit consequences of intrusions. plemented. If work zone crashes are concentrated in the daytime or weekdays, then Strategy 19.1 A4-use nighttime road work Level 3 Analysis and Strategy 19.1 F2-improve coordination, planning and In Level 3 analysis, work zone crashes are flagged but there scheduling of work activities may be effective in work zone is no work zone file or highway inventory. This analysis is de- crash reduction. pendent on crashes being flagged and how much information A large proportion of single vehicle crashes in work zones is obtained once they are flagged. If four fields are collected as may be a trigger to consider Strategy 19.1 B2-improve visi- recommended by the MMUCC then the Level 3 analysis can bility of work zone traffic control devices (particularity bar- be expanded to consider the type of work zone, the location riers), Strategy 19.1 B3-improve visibility of work zone per- within the work zone, and if workers are present at the time sonnel and vehicles, and Strategy 19.1 C2-implement of the crash. If the crash is simply flagged as a work zone crash measures to reduce work space intrusions (and limit conse- with no further details, the Level 3 analysis will be limited to quences of intrusions). a determination of the frequency and severity of work zone crashes versus all crashes in an agency. Level 4 Analysis Exhibit X-4 is taken from A Guide for Reducing Work Zone Collisions (17). While this exhibit contains only fatal crash If there is no flag for indicating a work zone crash, then it data, it is representative of the types of comparisons that can may be impossible to determine the nature of work zone be made in the Level 3 analysis. Results are typical of work crashes or if they are even a problem that should receive a pri- zone crash characteristics. ority treatment. Some crash forms do include fields that Results from this exhibit are outlined in A Guide for might indicate crashes related to work zones such as an item Reducing Work Zone Collisions and are typical of fatal work for "barricade" under traffic control, or "under repair" item zone accidents: in the road condition field. It may also be possible to manu- ally request the reports for recent major projects, and exam- · Almost 30 percent of fatal work zone crashes occurred on ine these crashes to determine the nature of the work zone urban or rural interstates, and this is more than double the crash problem. Strategy 19.1 F1-develop/enhance agency percentage of all fatal crashes. level work zone crash data systems should be a priority if no · Rear-end fatal crashes were over 2.5 times more common flag is available on the crash data form to indicate a work zone in work zones than in all fatal crashes. crash.
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85 Work Zone Fatal All Fatal Crashes Crashes Factor (Percent) (Percent) Time of Day Night 49 47 Day 50 52 Unknown 1 1 Day of Week Weekend 34 31 Weekday 66 69 Season Winter 22 16 Spring 24 26 Summer 27 31 Autumn 27 27 Roadway Function Rural, Interstate 7 13 Rural, Other 51 39 Urban, Interstate 6 15 Urban, Other 35 32 Unknown 1 1 Speed Limit 150 mph 44 38 5575 mph 52 58 Unknown 4 4 Number of Vehicles Involved One 57 53 Two 36 35 More Than Two 7 12 Manner of Two-vehicle Collision Rear-end 13 35 Head-on 26 21 Angle 32 22 Side-swipe, Opposite 21 15 Direction Side-swipe, Same Direction 6 7 Other or Unknown 2 1 Exhibit X-4. Comparison of factors: percentages of work zone and non-work zone fatal crashes (data from FARS, 2003).