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Results and Status of State Crash Analyses. IDS - Pool Fund. Presented to IDS Pool Fund Partners January 18, 2005. Outline. Crash Analysis - Preferred Process Wisconsin Process and Results North Carolina Process and Results Iowa Process and Results Comparison of States
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Results and Status of State Crash Analyses IDS - Pool Fund Presented toIDS Pool Fund Partners January 18, 2005
Outline • Crash Analysis - Preferred Process • Wisconsin Process and Results • North Carolina Process and Results • Iowa Process and Results • Comparison of States • Update on Michigan, New Hampshire, Georgia, and Nevada • Conclusions
Crash Analysis Process Determine Efficiency of State’s Crash Records System Census of All Rural Thru-STOP Intersections Very Efficient (i.e., MN & IA) Separate by facility type. Less Efficient (i.e., WI, NC, & MI) Sample of Rural Intersections - State Technical Liaison Screens to No More Than 75 Intersections State DOT Selection of Test Intersection 4-Legged; Two-Lane Roadways 4-Legged; Expressways Identify intersections over the critical crash rate. Detailed review of crash conditions. Top 3-6 Candidates Candidate Intersections, Two-Lane Candidate Intersections, Expressways Identify intersections with high crash frequency, severity, and number of crossing path crashes.
Wisconsin Process • Limitations of Wisconsin Crash System • Unable to automatically identify intersection locations • No ability to link traffic control and intersection geometry • State DOT Selected Corridor With Known Crash Problem • US 53 from Rice Lake to Superior (~ 70 miles) • Mainline volumes range from 4,700 to 11,000 vpd • 74 intersections had at least one crash in 6.5 year period (Jan. 1, 1999 to June 30, 2004) • 6 intersections were identified as candidates for deployment based on crash history
Typical Candidate Intersection Typical Median Design (CTH B, Douglas County) Typical Approach Design (EB Approach at CTH V, Barron County)
Vertical and Horizontal Curves Horizontal Curve at STH 77, Washburn County Crest Vertical Curve to North of CTH V, Barron County Horizontal Curve and Independent Vertical Alignment South of CTH B, Douglas County
Unique Features Median Design at STH 77, Washburn County Example Offset Right Turn Lane (CTH E and US 63, Washburn County)
North Carolina Process • Limitations of North Carolina Crash System • Unable to automatically query intersection locations based on traffic control and intersection geometry - creates difficulties in computing an expected rate for subsets • State DOT Selected Intersections from HSIP (Highway Safety Improvement Program) • The intent of HSIP is to “identify locations that exceed minimum warranting criteria developed by safety engineers for particular crash types and patterns for further analysis and investigation” • HSIP criteria used were I-1 (minimum number of frontal impact crashes) and I-5 (chronic crash pattern) • Intersections were also thru-STOP, and the major roadway was a four-lane divided highway with a speed limit > 55 mph • 59 of the top 300 HSIP intersections met the criteria, but only 12 had no safety improvement projects recently implemented
1) US 74 and SR 2210 3 4 6 2) US 74 and SR 1574 5 3) NC 87 and SR 1150 4) NC 87 and SR 1700 5) US 74 and SR 1152 1 6) US 19 and SR 1390 2 North Carolina Candidate Intersections
Iowa Process • Census of all rural, expressway intersections • Selected the 20 intersections with the greatest difference between the actual crash severity index rate and the expected crash severity index rate • From list of 20, screened down to the 6 intersections with the most failure to yield crashes
More Updates • Michigan • Completed initial overview of crash data and working to identify a corridor OR a subset of intersections for analysis • Georgia • Discussions with Technical Liaison continuing • Nevada • Discussions with Technical Liaison continuing • Indicated preference to focus analysis on rural two-lane roadways • New Hampshire • Discussions with Technical Liaison continuing • Indicated preference to focus analysis on rural two-lane roadways
Conclusions • Similar crash patterns have been found in Minnesota, Wisconsin, North Carolina, and Iowa • Similar crash rates, high severity, straight crossing path, farside location, gap related predominate • Many intersections have a high involvement of older and/or younger drivers • Weather and light conditions play minimal role in intersection safety problems