Bi-state metropolitan planning organization (MPO)

Transcription

1 Using a Variety of Data to Identify Locations of Concern in a Transportation Network 3 th Annual MN APA State Planning Conference September, 8 Robert Herling, Planner Duluth-Superior Metropolitan Interstate Council rherling@ardc.org (18) What is the MIC? Bi-state metropolitan planning organization (MPO) federally designated coordinate; provide leadership & technical support shared between ARDC (MN) and NWRPC (WI) Responsibilities Long-Range Transportation Plan (LRTP) - four years Transportation Improvement Program (TIP) - annually Unified Work Program (UWP) - annually Why identify locations of concern? Federal Transportation Bill SAFETEA-LU emphasis on safety data-driven decision making Functionally Classified Roads Per Capita Duluth/Superior UZA people miles ft / people 17, Funding limitations higher construction costs, but less funding available new emphasis on preservation vs. expansion find projects with best bang for buck Twin Cities UZA National Averages for UZAs,519, 59, 3, FHWA Highway Statistics Series Goal of Transportation Systems Management (TSM): Strategy: identify, quantify, and monitor Improved safety & efficiency through low-cost, high-benefit solutions MIC Project Objectives perform a system-wide assessment prioritize locations by needs provide a method of monitoring YEAR 1 Crashes per year High crash rate High severity rate YEAR 3 YEAR 5 YEAR 3 3 crashes per year Reduced crash rate High severity rate YEAR 5 3 Crashes per year Moderate crash rate Low severity rate 1

2 Challenges: running a system-wide analysis with any frequency balancing safety and efficiency needs balancing spot locations and road segments comparing needs between two states Solutions: thresholds to limit number of locations analyzed address spot locations and road segments separately two separate assessments (MN & WI) make the resources we have work for us Conventional measures for analysis: Safety crash frequency crash rate crash severity Mobility Level of service travel time delay time System-wide data available to the MIC: Safety state-available crash data ADT counts city, county, state Mobility level of service (LOS) from traffic model ADT counts city, county, state * System-wide travel time and delay data are cost-prohibitive MnDOT s Crash Mapping Analysis Tool (CMAT) MnDOT s Annual Average Daily Traffic Volumes (AADT) statewide data updated annually filtering capabilities provides a variety of info. stacker function

3 Started with a previous concept: 8 1 Initial attempt in : Adjusted Scale Only analyzed spot locations Safety threshold: 3 or more crashes in most recent year 5 year crash trend Mobility threshold: LOS D or poorer Did not compare MN results with WI results Current crash severity A B Collector/ Collector Minor/ Collector C D E F Level of service Minor/ Minor Major/ Collector Major/ Minor Major/ Major Functional class First assessment done in : Locations ranked with weight values (LOS given more influence) Problems with assessment: Too simplified Crash rate not the best measure for all cases Too much emphasis put on LOS For each location, analysis of conditions contributing to poor safety & capacity Suggested improvements: Use similar measures for both capacity and safety Use same number of measures for both Get rid of the weights * Quantify even-handedly & objectively The MIC MIC s assessment methodology methodology - NOT scientific - NOT statistically significant Theory: you can quantify anything + measure of relative performance + inexpensive + fair & balanced - from Burger Kings by Dara Grumdahl, Minnesota Monthly, July 8 3

4 MIC s s Improved methodology: Safety performance measures: Crash frequency (Quantity) Crash severity rate (Severity) Average increase in crash rate (Change) Mobility performance measures: AADT per lane mile (Quantity) LOS (Severity) % change in AADT (Change) Quantity measure for safety: Average number of crashes per year ( crashes ) example result: 8 crashes per year Severity measure for safety: Number of equivalent property damage crashes per million vehicles 1,, property ( damage x injury x fatality vehicles + + x x[ 1) ( crashes ) ( crashes entering 3) ] crashes Change measure for safety: Average change in crash rate vs. base year s s change in crash rate ( to 3) [ ] State Hwy 19 & Mesaba Ave 3 E th St & th Ave E total years x 35 days x intersection AADT example result:.9 crashes per 1 million vehicles Change in Rate.5 5 yr Avg. to 3 +. Change in Rate.5 to 3 5 yr Avg year 1 year Quantity measure for mobility: AADT per lane (factored by traffic control type) ( AADT number of lanes) where: x traffic control device factor No control (not an intersection) =.1 Roundabout =. Signal (protected L-turn for all) =.3 Signal (protected L-turn for some) =. Signal (no protected L-turns) =.5 Stop or Yield =. example result: vehicles per lane Severity measure for mobility: LOS as identified by TP Plus model ( A, B, C, D, E, F) where: example result: Score of LOS A = 1 LOS B = LOS C = 3 LOS A = LOS E = 5 LOS F =

5 Change measure for mobility: % change in AADT from 1 st year to last year (adjusted by func.. class) How can such different values be assessed even-handedly? ( AADT - AADT) AADT + ( FC1 + FC + FCn) 8 crashes per year.9 crashes per 1 million vehicles -.3 avg. change in crash rate Where FC is: Major arterial =.5 Minor arterial =. Major collector =.3 Major collector =. Local road =.1 vehicles per lane Score of. change in AADT example result:. change in AADT Answer: apply indexing Indexing I j = -1(X/R)+1 Indexing Composite scoring I j = -1(X/R) +1 Creates an individual score between 1 n C = Σ(I j ) j - 1 example: worst _ [( location s ) severity Severity rate rate worst _ best ] severity severity rate rate -1 x +1 Combines all individual scores for a final score between - Can prioritize locations by composite score Composite scoring n C = Σ(I j ) j index value index value index value for crash + for severity + for % change frequency rate In crash rate index value index value index value + ( for LOS) for AADT + + for % change per lane mi in AADT COMPOSITE SCORE E th St & th Ave E Arrowhead Rd US Hwy & & Kenwood Ave State Hwy 19 Skylin Pkwy & W 7th St State Hwy 19 & Mesaba Ave INTERSECTIONS 5

6 Or analyze locations in how they rank by safety or efficiency COMPOSITE SCORE E th St & th Ave E Arrowhead Rd & Kenwood Ave US Hwy & State Hwy 19 INTERSECTIONS Skylin Pkwy & W 7th St Safety Measures Mobility Measures State Hwy 19 & Mesaba Ave E th St & th Ave E: Mobility Issues th Ave E - Heading SW E th St - Heading NE * Lack of protected L-turns on E th St th Ave E th Ave E LOS D St th St E th LOS C Feet Skyline Pkwy & W 7 th St: Safety Issues * Inadequate sight distances Skyline Pkwy W 7 th St The methodology is NOT scientific NOT statistically significant IS a way to measure relative performance IS inexpensive W 7 th St - Heading SW IS fair & balanced Skyline Pkwy - Heading NE Questions? Robert Herling, Planner: rherling@ardc.org Duluth-Superior Metropolitan Interstate Council (MIC):