Data Needs for Tree Removal Crash Modification Factors on Arizona State Highways

The Arizona Department of Transportation (ADOT) Roadway Departure Safety Implementation Plan (RDSIP) has identified tree removal as a feasible countermeasure to reduce roadway departure crash frequency or severity. Previous ADOT work has identified locations for tree removal, and activities to conduct this work are underway. To test the safety effectiveness of removing the trees, ADOT intends to conduct statistically rigorous before‐after safety effectiveness analysis to estimate state‐specific crash modification factors (CMFs). This report provides a seven‐step data collection process, identifies and describes data needs, and recommends analytical methods for estimating the CMFs. The data needed for the analysis relate to crash type and severity, roadway characteristics, traffic volume, and tree removal. To complete the analysis, ADOT will compile the data before and after tree removal as outlined in this report and subsequently conduct the statistical analysis. The study team estimates that compiling, organizing, and managing the before‐after period database could be completed over the course of a month before and after tree removal has been completed. The statistical analyses may take approximately two months to conduct. This level of effort is an estimate and does not assume full‐time activity. In addition, the project analysis will not be conducted until three years after the tree removal has been completed at all sites.

• Record URL:
  https://apps.azdot.gov/ADOTLibrary/publications/project_reports/pdf/SPR721.pdf
• 
• Corporate Authors:

  Cambridge Systematics

  555 12th Street
  Suite 1600
  Oakland, CA  United States  94607

  Portland State University

  301B Northwest Center for Engineering, Science, and Technology
  Portland, OR  United States 

  Arizona Department of Transportation

  206 South 17th Avenue
  Phoenix, AZ  United States  85007

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Wemple, Elizabeth
  • Wu, Daniel
  • Monsere, Christopher
• Publication Date: 2016-7

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; References; Tables;
• Pagination: 62p

Subject/Index Terms

• TRT Terms: Before and after studies; Countermeasures; Crash data; Crash modification factors; Data collection; Estimating; Highway safety; Ran off road crashes; State highways; Trees
• Identifier Terms: Arizona Department of Transportation
• Subject Areas: Highways; Maintenance and Preservation; Safety and Human Factors;

Filing Info

• Accession Number: 01610878
• Record Type: Publication
• Report/Paper Numbers: FHWA‐AZ‐16‐721
• Contract Numbers: SPR 000‐1(183) 721
• Files: TRIS, ATRI, USDOT, STATEDOT
• Created Date: Sep 21 2016 2:40PM