Safety Prediction Method for Freeway Facilities with High-Occupancy Lanes

Abstract

The objective of this paper is to describe the development of a safety prediction method for freeways with high-occupancy vehicle (HOV) and high-occupancy toll (HOT) lanes, collectively referred to as HO lanes. This method has been developed and documented in a manner that is consistent with the safety evaluation methods in Part C of the Highway Safety Manual (HSM). Such a predictive methodology would assist state departments of transportation in explicitly considering safety performance impacts when planning, designing, and operating freeway facilities with HO lanes. Data were collected in California and Washington to support development of the predictive methodology. This method focuses on the evaluation of one freeway travel direction with each application. The paper summarizes key differences and similarities between this method and the current predictive method for freeways in Chapter 18 of the HSM Supplement. The method includes models for predicting total crash frequency and multiple-vehicle crash frequency. The method applies to freeway facilities with continuous HO lane access, buffer-separated HO lanes with intermittent access, and barrier/pylon-separate HO lanes with intermittent access between the HO lane(s) and the general-purpose lanes. The method does not differentiate between HOV and HOT designation.