01763476

Component

https://doi.org/10.1177/03611981211008447

Safety performance functions (SPFs) are essential tools to help agencies predict crashes and understand influential factors. Florida Department of Transportation (FDOT) has implemented a context classification system which classifies intersections into eight context categories rather than the three classifications used in the Highway Safety Manual (HSM). Using this system, regional SPFs could be developed for 32 intersection types (unsignalized and signalized 3-leg and 4-leg for each category) rather than the 10 HSM intersection types. In this paper, eight individual intersection group SPFs were developed for the C3R-Suburban Residential and C4-Urban General categories and compared with full SPFs for these categories. These comparisons illustrate the unique and regional insights that agencies can gain by developing these individual SPFs. Poisson, negative binomial, zero-inflated, and boosted regression tree models were developed for each studied group as appropriate, with the best model selected for each group based on model interpretability and five performance measures. Additionally, a linear regression model was built to predict minor roadway traffic volumes for intersections which were missing these volumes. The full C3R and C4 SPFs contained four and six significant variables, respectively, while the individual intersection group SPFs in these categories contained six and nine variables. Factors such as major median, intersection angle, and FDOT District 7 regional variable were absent from the full SPFs. By developing individual intersection group SPFs with regional factors, agencies can better understand the factors and regional differences which affect crashes in their jurisdictions and identify effective treatments.

The opinions, findings, and conclusions expressed in this paper are those of the authors and not necessarily those of the Florida Department of Transportation or the U.S. Department of Transportation. © National Academy of Sciences: Transportation Research Board 2021.

TRBAM-21-00113

English

pp 1545-1556

2021-9

Transportation Research Record: Journal of the Transportation Research Board

Digital/other

Figures; Maps; References (22) ; Tables

Classification; Highway safety; Intersections; Regional transportation; Residential areas; Suburbs; Urban areas

Highway Safety Manual; Safety Performance Functions

Florida

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

TRIS, TRB, ATRI

Dec 23 2020 11:01AM