Calibration Factors Handbook: Safety Prediction Models Calibrated with Texas Highway System Data (0-4703-5)

Highway safety is an ongoing concern to the Texas Department of Transportation (TxDOT). As part of its proactive commitment to improving highway safety, TxDOT is moving toward including quantitative safety analyses earlier in the project development process. The objectives of this research project are: (1) the development of safety design guidelines and evaluation tools to be used by TxDOT designers, and (2) the production of a plan for the incorporation of these guidelines and tools in the planning and design stages of the project development process. This document summarizes the research conducted and the conclusions reached during the development of safety prediction models for intersections and highway segments in Texas. Models were developed for urban and suburban arterial intersections, urban and suburban arterial street segments, rural multilane highway segments, and urban and rural freeway segments. They were subsequently calibrated using Texas highway system data. Selected accident modification factors were also developed and calibrated. These factors address several geometric design elements, including turn bay presence, median width, barrier presence, and weaving section length.