COMPARISON OF OPERATING SPEEDS ON DRY AND WET PAVEMENTS OF TWO-LANE RURAL HIGHWAYS
The impact of design parameters and traffic volume on operating speeds of passenger cars is evaluated under free-flow conditions on 322 curved roadway sections of two-lane rural highways in New York state. The design parameters considered are degree of curve, length of curve, superelevation rate, gradient, sight distance, lane width, shoulder width, posted speed, and average annual daily traffic. For the evaluation of the quantitative effects of these factors on operating speeds, expressed herein by the 85th-percentile speeds, the multiple linear stepwise regression technique was used. The various stages of analyses revealed that degree of curve was the best available single-variable predictor of operating speeds on dry pavements. Other variables helped the regression model, but the equation did well even without them. Effect of wet pavements on 85th-percentile speeds of passenger cars were also examined. Analyses were performed using data from a total of 24 curved roadway sections. Ample evidence exists to indicate that wet pavement does not have a great effect on operating speed, and that drivers will not adjust their speeds sufficiently to accommodate inadequate wet pavement on curves in particular. Furthermore, results of the statistical analyses indicate that the relationship between operating speed and degree of curve, developed from speed data collected on dry pavements, is also valid for wet pavement conditions so long as visibility is not affected appreciably by heavy rain. It is obvious that the drivers do not recognize the fact that friction supply is significantly lower on wet pavements as compared with dry. For the implementation of the results for design purposes, recommendations for achieving consistency and detecting inconsistencies in horizontal alignment, as well as recommendations for harmonizing design speed and operating speed, as related to wet pavement conditions, were given for good, fair, and poor design practices. These tasks are important in modern highway design and redesign strategies for improving traffic safety.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/isbn/0309050588
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Supplemental Notes:
- This paper appears in Transportation Research Record No. 1280, Transportation Management, HOV Systems, and Geometric Design and Effects 1990. 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:
- Lamm, Ruediger
- Choueiri, Elias M
- Mailaender, Theodor
- Publication Date: 1990
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 199-207
- Monograph Title: Transportation management, HOV systems, and geometric design and effects 1990
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Serial:
- Transportation Research Record
- Issue Number: 1280
- Publisher: Transportation Research Board
- ISSN: 0361-1981
Subject/Index Terms
- TRT Terms: 85th percentile speed; Alternatives analysis; Annual average daily traffic; Curvature; Dryness; Highway curves; Highway grades; Length; Multiple regression analysis; Operating speed; Pavements; Road shoulders; Rural highways; Sight distance; Slopes; Speed limits; Superelevation; Traffic lanes; Two lane highways; Wet weather; Width
- Uncontrolled Terms: Dry conditions; Wet pavements
- Old TRIS Terms: Multiple regression; Traffic lane width
- Subject Areas: Design; Highways; Pavements; Safety and Human Factors; I20: Design and Planning of Transport Infrastructure;
Filing Info
- Accession Number: 00605595
- Record Type: Publication
- ISBN: 0309050588
- Files: TRIS, TRB, ATRI
- Created Date: Mar 31 1991 12:00AM