1. HSM: Another Tool for Safety Management in Wyoming 1 Excellence in Transportation

2. Acronym Soup WYDOT – Wyoming Department of Transportation HSM – Highway Safety Manual ITE – Institute of Traffic Engineers SMS – Safety Management System CARE – Critical Analysis Reporting Environment CMF – Crash Modification Factor (AMF in HSM) B/C – Benefit-Cost Ratio NPV – Net Present Value SPF – Safety Performance Function RTM – Regression-to-the-mean ARF – Accident Reduction Factor (CRF in HSM) AADT – Annual Average Daily Traffic 2

3. Early Stages Started before the Highway Safety Manual was finally approved or published Highway Safety, Traffic, Road Design, and District Operations people did attend a one- day introductory training at an ITE meeting in May, 2010 Plan is to incorporate the quantitative processes into WYDOT’s Safety Management System 3

4. The WYDOT SMS Process Safety Issue Identification / quantification Safety Project Definition Safety Project Prioritization Project Planning Effectiveness Studies Project Deployment Prioritized opportunities to analyze Feedback Loop Candidate Safety Projects Benefits and costs; B/C Projects consolidated with other programs Prioritized safety project stack Updates to CMFs, Guidance Deployed & Operational Network Safety Index Pavement Project Recommendations Bridge Project Recommendations CARE Intersection Magic Safety Analyst Etc. Includes all Safety Projects For all Safety work Done in advance STIP, etc. Theme Studies District Inputs 4 Excellence in Transportation

5. Highway Safety Manual Crash modification factors Project planning input Process to calibrate for state 5 Excellence in Transportation

6. 6 Where the HSM fits in to Project Definition Safety Project Definition step Methods for estimating safety effectiveness (of a remedy / set of remedies) Appropriate SPF, calibration, multiple data sets, and CMF (limited) Select appropriate remedy(ies) Identify expected improvements (CMF) Calculate lifecycle benefits (NPV) Part C – Predictive Method (with calibrated SPF, HSM CMFs) Un-calibrated SPF and CMFs (HSM, Part D, others) Observed crash frequency and CMFs (HSM, Part D, others) Appropriate SPF, multiple data sets, and CMF Historical crash data and CMF, doesn’t address RTM In decreasing order of reliability; from HSM training (4.56) Needs for each Also, calculate lifecycle cost, project B/C ratio 6 Excellence in Transportation

7. Which Method to use? Use HSM Part C – Predictive Method –Pros: Most reliable (according to HSM) –Cons: Needs lots of data sets (WYDOT does not have several); needs calibration (extensive process) Use un-calibrated SPF –Pros: Still reliable (according to HSM) –Cons: Needs lots of data sets (WYDOT does not have several); Use observed (historic crashes) –Pros: Needs least amount of additional data; familiar to people (similar to previous use of ARF) –Cons: Least reliable (according to HSM) 7 Excellence in Transportation

8. 8 Applying CMF – Using observed crash frequency Observed crashes Specific Site being analyzed Select remedies Expected change in crash counts * Generally studies refer to Crash / Accident Reduction Factors which translate to CMF Expected benefits of remedy(ies) Identify CMF* 8 Excellence in Transportation

9. 9 Applying CMF – HSM Part C Predictive Method Select appropriate SPF (based on facility) Identify site characteristics (delta from baseline) Select Remedy(ies) Apply CMF Expected average crash frequency for the site Difference = expected benefits of remedy(ies) Determine SPF for site Find corresponding CMF for the remedy(ies) Up to 18 parameters From HSM lists (Part C, Part D) Calibrate each SPF Determine C for each SPF Determine volume for site (based on site) Adjust SPF Engineering judgement 9 Excellence in Transportation

10. HSM Part C – Expected average crash frequency (example; 2-lane rural highway segment) CMF(lw)CMF(swt)CMF(hc)CMF(se)CMF(gr)CMF(dd)CMF(crs)CMF(pl)CMF(2lt)CMF(rd)CMF(l)CMF(ase) Expected change in average crash frequency for specific site given selected remedies X XXXXXXXXXXX = Adjust for lane width Adjust for shoulder width, type… horizontal curve (3 factors)… superelevation… grade… driveway density… centerline rumble strips… passing lanes … roadside rating hazard … lighting … automatic speed enforcement … 2-way left turn lanes SPF for rural 2-lane AADT x Length + (365*10 -6 ) x e -0.312 X CMF 1 CMF 2 X … for selected remedies 1 - ( ) 10 Excellence in Transportation

11. HSM Core Data Needs for Segments FactorUnitWYDOT Status Length of segmentmilesOK AADTveh/dayOK 1 Lane widthftOK Shoulder widthftOK Shoulder typepaved, gravel, etc.OK Length of horizontal curvemiOK Radius of curvatureftOK Spiral transition presenty/nOK Superelevation varianceft/ftNot yet Grade%OK Driveway densitydriveways/mileWorking 2 Centerline rumble strips presenty/nAssume no Passing lanes presenty/nmaps 3 ?? Two-way left turn lanes presenty/nmaps 3 ?? Roadside rating hazard1-7 scalemaps 4 ?? Segment lighting presenty/nAssume no Auto speed enforcement presenty/nAssume no Calibration factorTBD NOTES: 1.However, need projected future traffic volumes 2.Data identified as coming from Pathways log. 3.Roadway width will catch many of these, but not all. Should we modify number of lanes table for this? 4.DCE’s agreed to gather this data in FY 2011, specifics to be determined? 11 Excellence in Transportation

12. Observations & Conclusions HSM Predictive method requires too much effort at this point –To obtain missing data sets, to perform SPF calibration HSM “Observed Crash Frequency” method can readily be used in WYDOT’s SMS approach –Easier to combine multiple remedies –Decision needed regarding “expected” crash rates Not all WYDOT remedies are covered by HSM Part C CMFs –Can also use Part D CMFs but with caveats Need additional data –Expected future traffic volumes (or at least growth rate) In order to calculate lifecycle crash reduction –Roadside data In order to support some of the CMFs (e.g. way left turn lanes, passing lanes, though partially available in the # lanes table) 12 Excellence in Transportation

13. Going Forward Who should attend HSM training? Finalize the starting remedies to consider for now Identify appropriate CMF values to use for each remedy –Work with District Traffic Engineers –Document logic for selection of values DiExSys is continuing research (Highway Safety) –Terrain (flat/rolling/mountainous) might be a sufficient surrogate for roadside hazard rating Address need for future traffic volume data Other possibilities –Prototype HSM calculation of expected average crash frequency for different segments using available data sets –Determine need/ability to get missing data sets 13 Excellence in Transportation