01763469

Component

https://annualmeeting.myt...nlineProgram/Details/15848

The Highway Safety Manual (HSM) provides guidance for agencies on developing safety performance functions (SPFs) to predict traffic crashes. However, some states develop their own SPF methodologies due to data differences and a need for additional roadway categories. The Florida Department of Transportation has developed a context classification system that groups intersections into eight categories, allowing for the development of regional context-specific SPFs. To best utilize this system, departments of transportation (DOTs) across the United States were surveyed about their current SPF development practices and context classification. Many states (64% of the 42 respondents) use HSM SPFs or SPFs calibrated to their jurisdiction. Although 62% of states had not heard of context classification, 67% of states expressed interest in it. One reason some states were not interested in using context classification was insufficient evidence of its benefits compared to the current HSM methodology. To showcase the increased accuracy of SPFs developed using this system, HSM SPFs [baseline, baseline with crash modification factors (CMFs), and calibrated with CMFs] for rural two-lane, two-way roads were compared with a context-specific SPF for C2T-Rural Town signalized four-leg intersections. These comparisons found that the HSM SPF with CMFs overpredicted crashes for Florida intersections (calibration factor of 0.87). The context-specific SPF contained additional variables (including a regional variable) not included in the baseline HSM SPF and performed statistically better than all three HSM SPFs. By implementing a similar context classification system, agencies could develop more accurate SPFs and identify regional differences, improving safety throughout their jurisdictions.

This paper was sponsored by TRB committee ACP10 Standing Committee on Regional Transportation Systems Management and Operations.

TRBAM-21-00078

English

21p

2021

Transportation Research Board 100th Annual Meeting

Digital/other

Figures; Maps; References; Tables

Crash risk forecasting; Four leg intersections; Predictive models; Regional transportation; Rural areas; Signalized intersections; State of the practice; Surveys; Towns; Two lane highways

Highway Safety Manual; Safety Performance Functions

Florida

Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors

Transportation Research Board Annual Meeting 2021 Paper #TRBAM-21-00078

TRIS, TRB, ATRI

Dec 23 2020 11:01AM