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Published byMagdalene Maxwell Modified over 9 years ago
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1 Element 1: The Systemic Safety Project Selection Process Element 1: 4-Step Project Selection Process
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Objective Develop a prioritized list of locations that could benefit from systemic safety countermeasures – Prioritized = Risk assessment for future crash; answers to question if all elements are equally at risk. – Location = Specific sites from focus facility type; including segments, curves, intersections, etc. 2 Element 1, Step 2: Screen and Prioritize Candidate Locations
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Outcome An assessment and rating of the focus facility type(s). Identify locations considered for systemic safety improvements. 3 Element 1, Step 2: Screen and Prioritize Candidate Locations
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Data Needs Location of focus facility type – Signalized intersections – Horizontal curves – Divided corridors – Etc. Site specific crash information – Severity, – Crash type – Relevant contributing factors Traffic and geometric information – At minimum, for risk factors – Additional information may be needed for selecting countermeasure 4 Element 1, Step 2: Screen and Prioritize Candidate Locations
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Element 1: Step 2 5 Element 1, Step 2: Screen and Prioritize Candidate Locations
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Element 1: Step 2, Task 1 Identify Network Elements Analyzed Purpose: Identify the all locations from the focus facilities – A census, not a sample Resources: Road and intersection data Crash data at statewide and regional levels Element 1: Step 2, Task 1 6
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Element 1: Step 2, Task 1 Identify Network Elements Analyzed Process: 1.Identify ALL locations from focus facility type. – Curves & Intersections: identify eligible locations – Segments: Split corridors into elements with consistent traffic and design characteristics (i.e., cross section) Identify logical segment endpoints 2. Are risk factors feasible for a systemwide analysis? – Did you notice anything that suggests a need to change risk factors? Element 1: Step 2, Task 1 7
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Sample Segment & Curve 8
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Element 1: Step 2, Task 2 Conduct Risk Assessment Purpose: Document the conditions (i.e., risk factors) at each location selected for analysis. Suggestion While collecting information about risk factors, consider what data might be needed to assign/select the countermeasure. Element 1: Step 2, Task 2 9
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Element 1: Step 2, Task 2 Conduct Risk Assessment Resources: GIS Electronic inventories of roadway features and traffic characteristics Data collected as part of a field review Archives of as-built plans Aerial photography/street views Video logs Traffic control device inventories Traffic flow maps Element 1: Step 2, Task 2 10
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Element 1: Step 2, Task 2 Conduct Risk Assessment Process: 1.Record roadway and traffic characteristics for the selected risk factors 2.Document crash history (particularly severe focus crashes) for each location. Element 1: Step 2, Task 2 11
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Example Data Collected for Segments 12
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Video Logs Edge Risk Assessment – See photos Lane Width Shoulder Width/Type Posted Speed Limit Curve Signing Sample Percent No Passing 13 2 – Usable Shoulder, Roadside with Fixed Objects 1 – Usable Shoulder, Reasonable Clear Zone 3 – No Usable Shoulder, Roadside with Fixed Obstacles 13
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Aerial Images for Segments Segment Access Points Curve – Visual Trap and Intersection 146/2011
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Aerial Images for Intersections Skew Intersection on/near horizontal curve Railroad crossing Commercial Development in quadrants 15
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Element 1: Step 2, Task 3 Prioritize Roadway Facilities Purpose: Use risk factors to assess locations’ risk. Identify top sites considered for countermeasure implementation. Element 1: Step 2, Task 3 16
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Element 1: Step 2, Task 3 Prioritize Roadway Facilities Process: 1.Prioritize roadway facilities using one of two methods to weight risk factors: – Equal weight to risk factors Identify the risk factors present for each location Sum the total number of risk factors for each location Prioritize locations based on number of risk factors present – Weighted risk factors Assign relative weights to each risk factor Calculate a score for each location Prioritize locations based on total score 2.Set a threshold (the number of risk factors present or a weighted value) used to identify high-priority candidates. 3.Flag the locations above the threshold. Element 1: Step 2, Task 3 17
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Example County Segment Prioritization Is the County’s entire system at-risk? – No, about 25% of their miles were determined to be a High Priority 18 Totals #%Mileage% 23%7.42% 45%17.94% 1621%75.319% 2836%150.638% 2026%108.027% -79%41.410% 77100%400.6100% RankCorridorRoute#StartEndLengthADT ADT Range RD Density Access Density Curve Critical Radius Density Edge Risk Totals Tiebreakers Edge Risk RD Density 1144.01CNTY89 CSAH-30 1.4 480 30.28 240.04CSAH40 NEW LONDON CORP LIMCSAH-2 5.9 450 20.17 3131.01CNTY89 CSAH-30MNTH-23 0.7 145 20.29 49.02CSAH9 CR-90, WILLMAR CORP LIMCSAH-10 5.6 940 10.14 55.06CSAH5 150TH AVE NW CSAH- 29CSAH-1 10.1 628 10.14 631.02CSAH31 NEW LONDON CORP LIMMNTH-23 1.6 920 10.13 78.01CSAH8 RENVILLE COUNTY LINE LAKE LILLIAN CORP LIM 3.6 750 20.33 84.01CSAH4 CSAH-8CSAH-20 6.7 320 20.09 92.05CSAH2 CSAH-10MNTH-23 9.8 385 20.04 104.04CSAH4 CR-98CSAH-40 2.4 290 20.00 1138.01CSAH38 CSAH-40CSAH-48 2.1 130 20.00 12132.01CNTY89 CSAH-8 2.2 190 20.00 1342.01CSAH42 CSAH-7COUNTY LINE 0.5 120 20.00 149.03CSAH9 CSAH-10 CSAH-40, REDWOOD ST 4.9 1,800 10.45 1525.01CSAH25 CSAH-5USTH-71 3.2 1,315 10.25 ………… …… … ……………………… ………… …… … ……………………… 741.03CSAH1 MNTH-23PENNOCK CORP LIM 7.0 333 10.03 75116.02CNTY89 CSAH-3MNTH-40 7.0 98 10.03 762.04CSAH2 ATWATER CORP LIMCSAH-10 6.7 1,018 10.00 7728.02CSAH28 CSAH-2COUNTY LINE 2.0 315 10.00 Total Stars --2633343322 % That Gets Star --36%46%47%46%31% Element 1: Step 2, Task 1
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Example County Curve Prioritization 19 Complete census of 504 curves 32 High Priority Curves (6%) 138 Curves in Proximity Chevrons in Place Stars#%#% 00%0 71%20% 255%41% 10821%10% 25050%20% -11423%51% 504100%143% Crashes Severe RoR Curve Count IDCorridorSegmentTotalSevereKABCPDOKA Radius (ft) Length Curve (ft) ADT Intersection on Curve Chevrons Visual Trap RankProximity Chevron Candidate 1001A1.01CSAH 1 1 - - - - - 1 - -9212550--- 2001B1.01CSAH 1 - - - - - - - - -55742250--- 3001C1.01CSAH 1 - - - - - - - - -82349350--- 4001D1.01CSAH 1 - - - - - - - - -37935950--- 5001E1.01CSAH 1 - - - - - - - - -66945650--- 6001F1.01CSAH 1 - - - - - - - - -27043150--- 7001G1.01CSAH 1 - - - - - - - - -31432450--- 8001H1.01CSAH 1 - - - - - - - - -54523950--- 9001I1.01CSAH 1 - - - - - - - - -45922550--- 10001J1.01CSAH 1 - - - - - - - - -36827450--- 11001K1.01CSAH 1 1 - - - - - 1 - -31839050--- 12001L1.01CSAH 1 - - - - - - - - -26739950-Yes- Installed 13001M1.01CSAH 1 - - - - - - - - -1,47534550--- 14001N1.01CSAH 1 - - - - - - - - -763578130Yes-- 15001O1.01CSAH 1 - - - - - - - - -859353210Yes-- 16002A2.02CSAH 2 1 - - - 1 - - - -583752930--- Yes 17002B2.02CSAH 2 - - - - - - - - -584635930Yes-- -Yes 18002C2.02CSAH 2 - - - - - - - - -799665930Yes-- -Yes 19002D2.02CSAH 2 - - - - - - - - -963626930--- Yes 20002E2.02CSAH 2 - - - - - - - - -1,234584930--- Yes 21002F2.02CSAH 2 - - - - - - - - -1,188719930--- Yes 22002G2.02CSAH 2 1 1 - 1 - - - - 1938556930--- -Yes 23002H2.02CSAH 2 - - - - - - - - -1,199402930--- Yes ………… … … … … … … … … ………………………… ………… … … … … … … … … ………………………… ………… … … … … … … … … ………………………… 502249ZH249.01CR 249 - - - - - - - - -432301275Yes-- 503249ZI249.01CR 249 - - - - - - - - -814344275--- Yes 504249ZJ249.01CR 249 - - - - - - - - -800685275--- Yes Element 1: Step 2, Task 1
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Example County Intersection Prioritization 20 Is the County’s entire system equally at- risk? – No, about 41% of their system is a High Priority #% 00% 00% 00% 811% 2130% 3346% 913% -00% 71100% Element 1: Step 2, Task 1
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