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OCR for page 82
82 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

OCR for page 82
83 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.