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Exhibit X-2. Application outputs (Ohio DOT).
when work zone rates are 50 to 100 percent greater than pre- type. Since it is not possible to determine work zone locations
work zone rates should be examined on a project-by-project and dates, it is not possible to determine exposure or to com-
basis. In Ohio, analyses of work zone crashes revealed that pute work zone crash rates.
many safety problems involved Interstate work zones with se- An example of a Level 2 analysis conducted by a state
vere congestion levels. If work zones on high volume road- highway agency is shown in Exhibit X-3. This exhibit shows
ways are a specific problem, then strategies aimed at reducing the frequency of work zone crashes by severity level and road
the number, duration and impact of work zones should be type. Severity of work zone crashes can be compared to the
examined. Project level reviews of crash data revealed nu- severity of all crashes. Also the severity of work zone crashes
merous crashes near on- and off-ramps. This result pointed by road type can be compared to the severity of all crashes by
to Strategy 19.1 C1 establish work zone design guidance, road type.
and Strategy 19.1 A1 improved maintenance and construc- Other computations are possible in the Level 2 analyses in-
tion practices. Specific details were added to Ohio's contract cluding the type of crash for work zone crashes, the month,
documents to reduce these crashes. There was also greater use day of the week, and time of day that work zone crashes
of night and weekend work schedules to minimize congestion occur. The greatest weakness of this analysis is the lack of
in work zones as discussed in Strategies 19.1 A4 use night- exposure information. This means that statistics, such as
time work zones, and 19.1 F2 improve coordination, 85 percent of work zone crashes occur during daytime, are
planning, and scheduling of work activities. difficult to interpret without knowing what percent of work
is being done during daytime, or the percent of vehicle miles
of travel that take place in daytime work zones. It is also not
Level 2 Analysis
possible to examine a portion of a work zone to find crash
In a Level 2 analysis, work zone crashes are flagged, and a concentrations such as shown in Exhibit X-2.
highway inventory is available that can be linked to crash data. At any analysis level other than Level 1, the Strategy 19.1
However, there is no file of work zone dates and locations. F1-develop/enhance agency level work zone crash data systems
Without the work zone file, it is not possible to categorize should be considered. To enhance this Level 2 analysis, an
work zone crashes by type of work, project type, or work zone agency would need to establish a work zone file that contains
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07/03/08
IOWA WORK ZONE CRASHES
(BY HIGHWAY SYSTEM AND CRASH SEVERITY)
Year Interstates State Highways County Roads City Streets Crash Type TOTAL
Totals CRASHES
F I PDO F I PDO F I PDO F I PDO F I PDO
1978 0 5 16 2 47 71 0 11 15 0 35 51 2 98 153 253
1979 0 5 51 0 33 64 0 11 19 0 38 79 0 87 213 300
1980 1 9 20 1 19 49 1 11 19 0 38 79 3 77 167 247
1981 2 5 15 1 38 52 0 10 18 0 28 57 3 81 142 226
1982 1 7 19 1 36 40 0 14 15 0 19 30 2 76 104 182
1983 3 12 25 2 49 57 0 6 9 1 27 43 6 94 134 234
1984 2 36 56 3 67 88 2 7 14 0 27 42 7 137 200 344
1985 2 17 42 4 58 81 0 10 12 0 24 39 6 109 174 289
1986 0 32 76 0 42 64 1 12 16 0 32 51 1 118 207 326
1987 5 21 7 0 57 101 1 10 16 0 17 35 6 105 159 270
1988 2 44 100 2 44 71 1 11 19 1 22 63 6 121 253 380
1989 0 43 110 2 38 85 2 11 18 0 20 51 4 112 264 380
1990 2 29 89 1 61 90 0 8 14 1 31 51 4 129 244 377
1991 5 32 101 3 50 88 0 11 16 0 30 62 8 123 267 398
1992 3 43 79 3 48 63 1 12 14 1 23 48 8 126 204 338
1993 3 55 76 1 35 65 0 13 19 0 32 49 4 135 209 348
1994 10 58 77 1 76 63 1 12 8 0 23 55 12 169 203 384
1995 2 47 77 1 51 53 0 12 15 0 29 53 3 139 198 340
1996 1 34 47 1 71 82 1 14 14 0 30 66 3 149 209 361
1997 5 49 61 5 56 69 0 14 10 0 31 55 10 150 195 355
1998 4 30 39 4 61 64 1 12 17 0 18 34 9 121 154 284
1999 4 45 69 13 85 89 0 12 12 0 31 56 17 173 226 416
2000 1 40 44 5 68 62 0 12 19 0 31 45 6 151 170 327
2001 1 n/a n/a 7 n/a n/a 0 n/a n/a 0 n/a n/a 8 n/a n/a n/a
2002 3 n/a n/a 0 n/a n/a 0 n/a n/a 0 n/a n/a 3 n/a n/a n/a
2003 5 n/a n/a 0 n/a n/a 0 n/a n/a 0 n/a n/a 5 n/a n/a n/a
1991 to
2000 38 433 670 37 601 698 4 124 144 1 278 523 80 1436 2035 3551
Totals
1991 to
2000 3.8 43.3 67.0 3.7 60.1 69.8 0.4 12.4 14.4 0.1 27.8 52.3 8.0 143.6 203.5 355.1
Average
Note: F = Fatality (Number of Actual Fatalities) Prepared By : Mark R. Bortle, PE
I = Injury (Number of Injury Crashes) Office of Construction
PDO = Property Damage Only (Number of PDO Crashes) Data From : Office of Traffic and Safety
Highway Division
Iowa Department of Transportation
Exhibit X-3. Example of a statewide work zone crash summary.
