SAFETY RELATIONSHIPS ASSOCIATED WITH CROSS-SECTIONAL ROADWAY ELEMENTS
This study was conducted to summarize the known relationships between accident experience and cross-sectional roadway elements, along with accident reductions expected because of related roadway safety improvements. Such elements include lane width, shoulder width, shoulder type, roadside features, bridge width, median design, and others. A detailed review of literature and available safety research revealed that accident types related to cross-sectional elements on two-lane roads include run-off-road (including fixed-object and rollovers), head-on, opposite direction sideswipe, and same direction sideswipe. Lane widening can reduce these related crashes by up to 40%, whereas shoulder widening can reduce related accidents by up to 49% [for the addition of 8-ft (2.4-m) paved shoulders]. Improving roadsides can also contribute to the reduction of as much as 44% [for a 20-ft (6.1-m) increase in clear zone], whereas sideslope flattening can reduce single vehicle crashes up to 27% (for flattening a 2:1 sideslope to 7:1 or flatter). Bridge widening can reduce total bridge crashes by as much as 80%, depending on the width before and after widening. On multilane roads, wider and flatter medians are associated with a reduced rate of total crashes. Lower-cost multilane design alternatives found to reduce crashes compared to two-lane roadways include two-way left-turn lanes, passing lanes, and turnout lanes. Suburban and rural multilane designs found to significantly reduce crashes compared to two-lane roads include those roads having two-way left-turn lanes with three or more total lanes.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/issn/03611981
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Supplemental Notes:
- This paper appears in Transportation Research Record No. 1512, Safety Effects of Roadway Design Decisions. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
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Authors:
- Zegeer, Charles V
- Council, Forrest M
- Publication Date: 1995
Language
- English
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 29-36
- Monograph Title: Safety effects of roadway design decisions
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Serial:
- Transportation Research Record
- Issue Number: 1512
- Publisher: Transportation Research Board
- ISSN: 0361-1981
Subject/Index Terms
- TRT Terms: Crash types; Cross sections; Frontal crashes; Guides to the literature; Highway design; Highway safety; Highways; Improvements; Literature reviews; Medians; Passing lanes; Railroad turnouts; Ran off road crashes; Road shoulders; Roadside improvement; Rollover crashes; Safety; Side crashes; Single vehicle crashes; Slopes; Traffic lanes; Traffic safety; Two lane highways; Two way left turn lanes; Width
- Uncontrolled Terms: Fixed objects; Lane width; Shoulder width; Side slopes
- Old TRIS Terms: Bridge width
- Subject Areas: Design; Highways; Safety and Human Factors; I20: Design and Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure;
Filing Info
- Accession Number: 00715638
- Record Type: Publication
- Files: TRIS, TRB, ATRI
- Created Date: Jan 23 1996 12:00AM