Abstract
The roadside of horizontal curves should be cleared of any obstructions to satisfy sight distance (SD) requirements. This paper proposes an innovative roadside design curve for the required lateral clearance (offset) on simple horizontal curves. The roadside curve consists of a circular curve connected with two spiral curves and exhibits several advantages: (1) it provides a smooth SD profile that improves design consistency; (2) it has beneficial effects on safety for sharp horizontal curves; and (3) it leads to the development of a simple design aid. The roadside curve provides a good approximation of the required lateral offset for roadway simple horizontal curves with a length lesser or greater than the required SD. The results show that approximately two-thirds of the maximum lateral offset required by the American Association of State Highway and Transportation Officials should be provided at half of the required SD upstream and downstream of simple horizontal curves. The concept of roadside curve is similar to the design of spiraled horizontal curves and thus will be easily understood by highway designers.
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Acknowledgments
This research was supported by a Discovery Grant from the Natural Sciences and Engineering Council of Canada.
References
AASHTO. (2011). “A policy on geometric design of highways and streets.” Washington, DC.
Aram, A. (2010). “Effective safety factors on horizontal curves of two-lane highways.” J. Appl. Sci., 10(22), 2814–2822.
Berg, W. D., Choi, J., and Kuipers, E. J. (1989). “Development of highway alignment information from photolog data.” Transp. Res. Rec., 1239, 54–61.
California Department of Transportation. (2012). Highway design manual, Sacramento, CA.
Easa, S. M. (1991). “Lateral clearance to vision obstacles on horizontal curves.” Transp. Res. Rec., 1303, 22–32.
Easa, S. M. (1993). “Lateral clearance needs on compound horizontal curves.” J. Transp. Eng., 111–123.
Easa, S. M. (1994). “Design considerations for highway reverse curves.” Transp. Res. Rec., 1445, 1–11.
Fink, K. L., and Krammes, R. A. (1995). “Tangent length and sight distance effects on accident rates at horizontal curves on rural two-lane highways.” Transp. Res. Rec., 1500, 162–168.
Glennon, J. C. (1987). “Effects of sight distance on highway safety.” Transp. Res. Board State Art Rep., 6, 64–77.
Harwood, D. W., Neuman, T. R., and Leisch, J. P. (2000). “Summary of design speed, operating speed and design consistency issues.” Transp. Res. Rec., 1701, 116–120.
Hassan, Y., Easa, S. M., and Abd El Halim, A. O. (1995). “Sight distance on horizontal alignments with continuous lateral obstructions.” Transp. Res. Rec., 1500, 31–42.
Hassan, Y., Easa, S. M., and Abd El Halim, A. O. (1996). “Analytical model for sight distance analysis on three-dimensional highway alignments.” Transp. Res. Rec., 1523, 1–10.
Hassan, Y., Easa, S. M., and Abd El Halim, A. O. (1997). “Modeling headlight sight distance on three-dimensional highway alignments.” Transp. Res. Rec., 1579, 79–88.
Hassan, Y., Easa, S. M., and Abd El Halim, A. O. (1998). “Highway alignment: Three-dimensional problem and three-dimensional solution.” Transp. Res. Rec., 1612, 17–25.
Jha, M. K., Karri, G. A. K., and Kuhn, W. (2011). “New three-dimensional highway design methodology for sight distance measurement.” Transp. Res. Rec., 2262, 74–82.
Liu, C. (2013). “Exact sight distance determination on compound vertical and horizontal curves in the presence of road barriers.” Int. J. Transp. Sci. Technol., 2(2), 159–166.
Liu, C., and Wang, Z. (2012). “Deriving sight distance on a compound sag and circular curve in a three dimensional space.” Int. J. Transp. Sci. Technol., 1(3), 297–304.
Lovell, D. J. (1999). “Automated calculation of sight distance from horizontal geometry.” J. Transp. Eng., 297–304.
Lovell, D. J., and Iida, I. (2003). “The exact clear zone envelope for piecewise-linear alignment data.” Transp. Research Part B Methodological, 37(5), 485–499.
Lovell, D. J., Jong, J. C., and Chang, P. C. (2001a). “Clear zone requirements based on horizontal sight distance considerations.” Transp. Res. Part A Policy Pract., 35(5), 391–411.
Lovell, D. J., Jong, J. C., and Chang, P. C. (2001b). “Improvements to sight distance algorithm.” J. Transp. Eng., 283–288.
Mauga, T. (2014). “Horizontal clearance offsets to objects higher than sightlines.” Transp. Res. Rec., 2436, 23–31.
Mauga, T. (2015a). “Minimum roadside clearance offsets on the inside of reverse curves based on flat spirals.” J. Transp. Technol., 5(3), 169–184.
Mauga, T. (2015b). “New spiral curves for appropriate transition of minimum roadside clearance on simple curves.” J. Transp. Technol., 5(3), 141–158.
Mauga, T., Ghanma, M., and Ahmed, K. (2013). “Roadside clearance limit on horizontal curves with transitional arcs.” Transp. Res. Rec., 2358, 20–28.
Medina, A. M. F., and Tarko, A. P. (2005). “Speed factors on two-lane rural highways in free-flow conditions.” Transp. Res. Rec., 1912, 39–46.
Olson, P. L., Cleveland, D. E., Fancher, P. S., and Schneider, L. W. (1984). “Parameters affecting stopping sight distance.”, Washington, DC.
Ottesen, J. L., and Krammes, R. A. (2000). “Speed-profile model for design-consistency evaluation procedure in the United States.” Transp. Res. Rec., 1701, 76–85.
Raymond, W. L. (1972). “Offsets to sight obstructions near the ends of horizontal curves.” J. Civ. Eng., 42(1), 71–72.
Sarhan, M., and Hassan, Y. (2012). “Consideration of sight distance in placement of concrete barriers on horizontal curves of roads.” Transp. Res. Rec., 2301, 9–16.
Tom, G. K. J. (1995). “Accidents on spiral transition curves.” Inst. Transp. Eng. ITE J., 65(9), 49–53.
TRB (Transportation Research Record). (2016). “Vehicle paths on horizontal transition curves.” 〈http://rns.trb.org/dproject.asp?n=27112〉 (Feb. 1, 2016).
Waissi, G. R., and Cleveland, D. E. (1987). “Sight distance relationship involving horizontal curves.” Transp. Res. Rec., 1122, 96–107.
Weale, K. H. M. (2006). “Designing for the road user: Maximum spiral transition lengths.” Institution of Professional Engineers New Zealand Transportation Conf., Institution of Professional Engineers New Zealand (IPENZ) Transportation Group, Wellington, New Zealand.
Wood, J. S., and Donnell, E. T. (2014). “Stopping sight distance and horizontal sight line offsets at horizontal curves.” Transp. Res. Rec., 2436, 43–50.
Information & Authors
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Published In
Journal of Transportation Engineering
Volume 142 • Issue 11 • November 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Nov 16, 2015
Accepted: Apr 25, 2016
Published online: Jun 28, 2016
Published in print: Nov 1, 2016
Discussion open until: Nov 28, 2016
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