Optimum Curvature for Simple Horizontal Curves
Publication: Journal of Transportation Engineering
Volume 120, Issue 5
Abstract
A model based on an expected total‐cost minimization approach is developed for determining the optimal‐degree curvature of simple horizontal curves on undivided two‐lane highways. Expected total cost is defined as the sum of the construction costs and the expected cost of accidents. Construction cost is treated as a deterministic function of curvature, and the expected cost of accidents is determined in relation to the amount by which required (demand) curvature differs from design (supply) curvature. It is shown that the optimal degree of curvature is highly sensitive to the skewness of the probability distribution of the required curvature. This distribution is derived from the fundamental relationship between speed and degree of curvature, treating speed to be a random variable. The optimal value is shown to change in direct proportion to skewness of the speed distribution. User cost, in terms of travel time, is treated as a special case when examining the sensitivity of optimal design curvature to construction‐ and accident‐cost functions. Model applications in curve design are illustrated by a numerical example.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Babalola, A. (1988). “Geometric design of right turning lanes on at‐grade intersections through optimization.” Nigerian J. Engrg., 5(1), 42–52.
2.
Cleveland, D. E., Kostynvik, L. P., and Ting, K.‐L. (1985). “Design and safety on moderate volume two‐lane roads.” Transp. Res. Record 1026, Transportation Research Board, Washington, D.C., 51–61.
3.
“Designing Safer Roads.” (1987). Spec. Rep. 214, Transportation Research Board (TRB), Washington, D.C.
4.
Hirsh, M., Prashker, J. N., and Ben‐Akiva, M. (1986). “New approach to geometric design of highways.” Transp. Res. Record 1100, Transportation Research Board (TRB), Washington, D.C., 50–57.
5.
Islam, M. N., and Seneviratne, P. N. (1992). “Estimating operating speeds for design consistency evaluation.” Proj. Rep., Center for Advanced Transportation Studies, Utah State University, Logan, Utah.
6.
Kerman, McDoald, M., and Mintsis, G. A. (1982). “Do vehicles slow down on bends? A study into road curvature, driver behavior and design.” Traffic Engineering Division, University of Southampton, Southampton, England.
7.
Lamm, R. (1984). “Driving dynamic considerations: a comparison of German and American friction for highway design.” Transp. Res. Record 960, Transportation Research Board (TRB), Washington, D.C., 13–22.
8.
Lamm, R., Chouciri, E. M., Haywood, J. C., and Paluri, A. (1988). “Possible design procedure to promote design consistency in highway geometric design on two‐lane rural roads.” Transp. Res. Record 1195, Transportation Research Board (TRB), Washington, D.C., 111–122.
9.
Leisch, J. E., and Leisch, J. P. (1977). “New concept in design‐speed application.” Transp. Res. Record 631, Transportation Research Board (TRB), Washington, D.C., 4–14.
10.
McBean, P. A. (1982). “The influence of road geometry at sample accident sites.” TRRL Lab. Rep. 1053, Transport and Road Research Laboratory (TRRL), Berkshire, England.
11.
McLean, J. R. (1981). “Driver speed behavior and rural road alignment design.” Traffic Engrg. & Control, 22(4), 208–211.
12.
Neuman, T. R. (1985). “Discussion of ‘Superelevation and roadway geometry: deficiency at crash sites and on grades.‘” Transp. Res. Record 1026, Transportation Research Board (TRB), Washington, D.C., 47–49.
13.
Neuman, T. R., and Glennon, J. C. (1983). “Cost‐effectiveness of improvements to stopping‐sight‐distance safety problems.” Transp. Res. Record 923, Transportation Research Board (TRB), Washington, D.C., 26–34.
14.
A Policy on Geometric Design of Highways and Streets. (1990). American Association of State Highway and Transportation Officials (AASHTO), Washington, D.C.
15.
Polus, A., Livneh, H., and Craus, J. (1984). “Effect of traffic and geometric measures on highway average running speed.” Transp. Res. Record 960, Transportation Research Board (TRB), Washington, D.C., 34–39.
16.
Ravindran, A., Phillips, D. T., and Solberg, J. J. (1987). Operations research principles and practice, 2nd Ed., John Wiley and Sons, New York, N.Y.
Information & Authors
Information
Published In
Copyright
Copyright © 1994 American Society of Civil Engineers.
History
Received: Dec 10, 1992
Published online: Sep 1, 1994
Published in print: Sep 1994
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.