HORIZONTAL SIGHT DISTANCE CONSIDERATIONS IN FREEWAY AND INTERCHANGE RECONSTRUCTION
With improvements being made to freeways and expressways, the problem of inadequate stopping sight distance on curves accompanying installation of a concrete barrier may arise. This could also occur when lanes are added in the median of a freeway or expressway and a narrow median results. It also may become a problem on curved ramps on structures where the parapet may not be offset sufficiently from the traveled-way. One solution to the problem for freeway medians is to provide a wider shoulder (greater offset to barrier) for the traveled-way turning to the left. Where a constant median width exists, the left shoulder for the opposing direction is, of course, narrowed. When a ramp is on a structure (bridge or retaining wall) and there is a curve to the left, the traveled-way can be shifted to the right, providing a wider left shoulder for sight distance and breakdown. The right shoulder would then be narrowed, preferably to not less than 4 ft. It must be kept in mind that stopping sight distance is only one of many design and operational considerations in planning an improvement. There certainly can be trade-offs with other features and the potential influence on accident experience. Further study is needed to ascertain the optimum dimensions of all cross-sectional elements to best satisfy safety, operational, and design requirements.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/isbn/0309048079
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Supplemental Notes:
- This paper appears in Transportation Research Record No. 1208, Highway Sight Distance Design Issues. 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:
- Leisch, Joel P
- Publication Date: 1989
Media Info
- Features: Figures; Photos; References;
- Pagination: p. 80-84
- Monograph Title: Highway sight distance design issues
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Serial:
- Transportation Research Record
- Issue Number: 1208
- Publisher: Transportation Research Board
- ISSN: 0361-1981
Subject/Index Terms
- TRT Terms: Curves (Geometry); Freeways; Interchanges; Medians; Offsets (Traffic signal timing); Reconstruction; Road shoulders; Sight distance; Stopping sight distance
- Subject Areas: Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure;
Filing Info
- Accession Number: 00490649
- Record Type: Publication
- ISBN: 0309048079
- Files: TRIS, TRB, ATRI
- Created Date: Jan 31 1990 12:00AM