Publication Details

The development of crash modification factors: Highway safety statistical paper synthesis

Type: Paper

Subtype: Final report

Author(s): Donnell, Eric; Hanks, Ephraim; Porter, Richard J.; Cook, Lawrence; Srinivasan, Raghavan; Li, Fan; Nguyen, Maggie; Eccles, Kimberly

Publisher: Federal Highway Administration

Url: https://www.fhwa.dot.gov/publications/research/safety/20069/20069.pdf

Publication Date: Nov-2020

Number: FHWA-HRT-20-069

Address: McLean, VA

Abstract: The transportation-engineering community is transforming by integrating quantitative methods into the task-development process. This report identifies opportunities to better understand the relationships between road safety and factors that affect traffic-crash occurrence and severity. In this report, current statistical-analysis methods and data sources used in road-safety research are compared with alternative methods and data sources. Causal-inference methods are compared to observational before--after methods to develop safety-effect estimates of centerline and edgeline rumble strips. Regression trees and Random Forests™ are compared to count regression methods to predict crash frequencies on freeways. Road-safety performance estimates using the Crash Outcomes Data Evaluation System are also discussed, with a focus on opportunities to link hospital and crash data to understand the relationship between crashes and site-specific contributing factors. Methods to account for underreporting in crash-frequency models are also described.