Turner-Fairbank Highway Research Center

« back to the list

Effects of a Towaway Reporting Threshold on Crash Analysis Results

Product Type

HSIS Summary Report


Charles V. Zegeer, Herman F. Huang, J. Richard Stewart, Ron Pfefer, Jun Wang




The effects of converting to a towaway reporting threshold on future data analysis capabilities are quantified. The results from the four states used in the analysis (Illinois, Michigan, Minnesota, and North Carolina) revealed that only 51.7 percent of all crashes would be included using a towaway threshold. Only 33.7 percent would be included using an injury threshold. In general, a towaway threshold would exclude more crashes on urban streets than on rural roads. For most road classes, 40 to 60 percent of crashes would be excluded. With a towaway threshold, about 40 to 60 percent of angle/turning and rear-end crashes, but only 18 to 32 percent of backing/ parking and animal crashes, would be included. Run-off-road crashes would be less affected. For most vehicle types, only 30 to 60 percent of crashes would be included. Using a towaway threshold will seriously affect the comprehensiveness of crash records, and thus, the ability to identify and improve high-hazard locations. Technological, institutional, and organizational strategies for improving reporting thresholds are suggested.

Link To HSIS Summary Report

Effects of a Towaway Reporting Threshold on Crash Analysis Results


Reporting Threshold
Crash Analysis

« Back to the List

HSIS Summaries

HSIS Summary Reports are two to eight pages in length and include a brief description of the issue addressed, data used, methodology applied, significant results, and practical implications.

Read More

Research Reports

A variety of research studies have been performed using data from HSIS. Many of the final reports prepared are now available electronically.

Read More

Technical Summaries

Research reports are often summarized in executive summaries, technical briefs, or other abbreviated formats. Included here are those road safety summaries that involved research using HSIS data.

Read More

Safety Analysis Tools

In addition to conducting research, HSIS resources are also used to develop products that can be used by practitioners in the analysis of safety problems.

Read More

Other Projects

HSIS data are sometimes used in research studies that result in other types of finished products, such as dissertations, theses, and conference proceedings.

Read More