Calibration and Development of Safety Performance Functions for Rural Two-Lane Two Way Roadways: A New Jersey Case Study

Calibrating the safety performance functions (SPF) in the Highway Safety Manual (HSM) and developing jurisdiction-specific SPFs both require significant time, effort and resources, and detailed data from different sources. It is therefore crucial to identify all the readily available data sources and automatically gather much of the data required by the HSM. However, datasets maintained by the state transportation agencies are rarely comprehensive enough to meet all data requirements, often including errors and inconsistencies. This paper presents a detailed discussion of data needs and availability, data processing methods and approaches to gather the required data for calibration and development of SPFs using rural two-way two-lane rural roadway segments and intersections in New Jersey (NJ) as a case study. It is shown that generating a usable dataset from various different data sources is a rigorous task of data compiling, cleaning and processing, and requires a significant computer programming effort. While presenting the results of the SPF calibration and development process, this paper points to the importance of crash location information and its impact on analyses results. In addition, through past literature and best practices, this paper also discusses the practicality of the current manual data extraction practices, and argues that novel data extraction methods, such as the clustering approach used in this study, should be adopted to minimize labor-intensive and cost-prohibitive manual data collection processes and increase data accuracy. The choice between calibration and development of jurisdiction-specific SPFs is also discussed.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 18p

Subject/Index Terms

Filing Info

  • Accession Number: 01764271
  • Record Type: Publication
  • Report/Paper Numbers: TRBAM-21-02992
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 23 2020 11:24AM