Regionalized Urban-suburban Collector Road Safety Performance Functions

Monday, April 29, 2019 - 17:00

The purpose of this project was to estimate regionalized safety performance functions (SPFs) for urban and suburban collector roads and at-grade intersections using roadway inventory and crash data from state-owned roadways in Pennsylvania. Five years of crash data (2013-2017) were appended to traffic volume and roadway and roadside features in order to estimate statistical models of total and  fatal  +  injury  crash  frequency.  SPFs were  developed  for  two-lane  undivided  roadway  segments  and  the  following  at-grade intersections types: three-leg intersections with stop-control on the minor approach; three-leg intersections with all-way stop control; four-leg intersections with stop-control on the minor approach, four-leg intersections with all-way stop control; and four-leg signalized intersections.   Based   on   the   regionalization   process,   engineering   district-level   SPFs   with   county-leveladjustments   were   recommended for two-lane undivided roadway segments. Statewide SPFs were recommended for three-leg all-way stop controlled, four-leg  minor-street  stop-controlled,  four-leg  all-way  stop-controlled  and  four-leg  signalized  intersections.  Statewide  SPFs  with  district-level adjustments were recommended for three-leg minor-street stop-controlled intersections.  The full report is available online at


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