Safety Performance of Part-Time Shoulder Use on Freeways, Volume 1: Informational Guide and Safety Evaluation Guidelines (2021)

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2 INTRODUCTION ..................................................................................................................................... 3  PTSU TRADEOFFS .................................................................................................................................. 4  Operational Performance ................................................................................................................................... 4  Safety Performance ........................................................................................................................................... 5  Project 17‐89 Crash Frequency Prediction Model Findings ...................................................................................... 5  Project 17‐89 Severity Distribution Prediction Model Findings ................................................................................ 7  Project 17‐89 Crash Cost Evaluation ......................................................................................................................... 8  Project 17‐89 Supplemental Safety Findings ............................................................................................................ 9  Shoulder Open versus Shoulder Closed ............................................................................................................. 10  Shoulder Closed versus no PTSU ........................................................................................................................ 10  Left‐side versus Right‐side PTSU ........................................................................................................................ 10  Dynamic Signs versus Static Signs ...................................................................................................................... 11  Dynamic Operation versus Static Operation ...................................................................................................... 11  Project 17‐89 Safety Finding Summary ................................................................................................................... 12  PTSU PREDICTIVE SAFETY ANALYSIS .......................................................................................... 12  Introduction ...................................................................................................................................................... 12  Evaluation Process ............................................................................................................................................ 13  Analysis Steps.......................................................................................................................................................... 13  Data Requirements ................................................................................................................................................. 13  Segmentation Process ............................................................................................................................................ 13  Alternative Analysis ................................................................................................................................................ 14  ANALYSIS TOOL .................................................................................................................................... 14  REFERENCES .......................................................................................................................................... 15  Photo Credits Cover – Lee Rodegerdts 1(a), 4(a) – Anusha Musunuru 1(b), 4(b), 5(b) – Andrew Butsick 2, 3(a), 3(b), 5(a), 6(a), 6(b) – Pete Jenior