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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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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).
