Investigation of Median Trees and Collisions on Urban and Suburban Conventional Highways in California

This study examines safety in the presence of large trees in curbed medians of conventional highways that are also principal streets in developed urban and suburban areas. Statistical modeling methods were used to associate collision frequency and severity with highway and traffic characteristics, with and without median trees. The methods include simple accident rates and three types of multivariate modeling and use collision data for 6 years. The analysis was done in two parts. The first part was a screening investigation of pertinent facilities under both state and local jurisdiction. The second part, described here in detail, focused on 14,283 collisions occurring on 58 mi (99 km) of designated state highways in 29 different sections, 19 with median trees. The analysis examined different subsets of reported collisions, in turn omitting collisions on the right side of the road, collisions not having median or median-shoulder involvement, and collisions at intersections. The overall conclusion is that large trees in medians of major conventional urban and suburban highways of state jurisdiction are associated with more collisions and increased severity. However, some of these associations are statistically weak. For the situations examined, lower speeds and larger side clearances were not found to mitigate the increased collision impacts associated with median trees.

• Record URL:
  https://doi.org/10.3141/1908-14
• 
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=Investigation+of+Median+Trees+and+Collisions+on+Urban+and+Suburban+Conventional+Highways+in+California&author=E.+Sullivan&author=J.+Daly&publication_year=2005
• Availability:
  • Find a library where document is available. Order URL: http://www.trb.org/Main/Public/Blurbs/156687.aspx
• Authors:
  • Sullivan, Edward C
  • Daly, James C
• Publication Date: 2005

Language

• English

Media Info

• Media Type: Print
• Features: References; Tables;
• Pagination: pp 114-120
• Monograph Title: Statistical Methods; Highway Safety Data, Analysis, and Evaluation; Occupant Protection; Systematic Reviews and Meta-Analysis
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 1908
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Arterial highways; Crash rates; Crash severity; Medians; Multivariate analysis; Speed; State highways; Suburbs; Trees; Urban areas
• Geographic Terms: California
• Subject Areas: Data and Information Technology; Design; Highways; Safety and Human Factors; I82: Accidents and Transport Infrastructure;

Filing Info

• Accession Number: 01006619
• Record Type: Publication
• ISBN: 0309093805
• Files: TRIS, TRB, ATRI
• Created Date: Oct 28 2005 4:14PM