Design Consistency Index for Two-lane Roads based on Continuous Speed Profiles
It is well known that road accidents tend to be more frequent in locations where a sudden change in road characteristics violates the driver's expectations. Most methods used to assess the design consistency are based on simplified speed profiles that give a coarse description of the vehicle dynamics along the road. This paper presents a new approach to quantify the road design consistency, based on continuous operating speed profiles. These profiles are based on the Gipps’ car-following equations, adapted to simulate the driver behaviour in the vicinity of horizontal curves under free-flow conditions. A methodology to calibrate and validate the Gipps’ behavioural parameters from field data is presented and applied to predict the speed profiles of three drivers for a set of rural road segments. The calibration is based on trajectory data collected with an instrumented vehicle and it follows an automated procedure that aims to minimize the differences between the predicted and observed speed profiles. The new consistency index is based on the deceleration distances and it allows to overcome some limitations of the existing methods.
 TRB. Modeling operating speed: synthesis report. Operational Effects of Geometrics Committee, 2011. Available from: http://onlinepubs.trb.org/onlinepubs/circulars/ec151.pdf
 Gibreel GM, Easa SM, Hassan Y, El-Dimeery IA. State of the Art of Highway Geometric Design Consistency. Journal of Transportation Engineering. 1999;125(4): 305-13. doi:10.1061/(ASCE)0733-947X(1999)125:4(305)
 AASHTO. A Policy on Geometric Design of Highways and Streets 2011. American Association of State Highway and Transportation Officials; 2011.
 TRB. HCM 2010: Highway Capacity Manual. Washington, D.C.: Transportation Research Board – National Research Council; 2010.
 Morrall J, Talarico R. Side friction demanded and margins of safety on horizontal curves. Transportation Research Record. 1994;1435: 145.
 Passetti K, Fambro D. Operating Speeds on Curves With and Without Spiral Transitions. Transportation Research Record: Journal of the Transportation Research Board. 1999;1658: 9-16. doi:10.3141/1658-02
 Fitzpatrick K, Elefteriadou L, Harwo od DW, Collins J, Mc-Fadden J, Anderson IB, et al. Speed prediction for twolane rural highways. US Department of Transportation; 2000. Available from: https://www.fhwa.dot.gov/publications/research/safety/ihsdm/99171/99171.pdf
 Misaghi P, Hassan Y. Modeling Operating Speed and Speed Differential on Two-Lane Rural Roads. Journal of Transportation Engineering. 2005;131(6): 408-18. doi:10.1061/(ASCE)0733-947X(2005)131:6(408)
 Ye Q, Tarko A, Sinha K. Model of Free-Flow Speed for Indiana Arterial Roads. Transportation Research Record: Journal of the Transportation Research Board. 2001;1776: 189-93. doi:10.3141/1776-24
 Correia GHdA, Silva AB. Setting Speed Limits on Rural Two-Lane Highways by Modeling the Relationship between Expert Judgment and Measurable Roadside Characteristics. Journal of Transportation Engineering. 2011;137(3): 184-92. doi:10.1061/(ASCE)TE.1943-5436.0000210
 Lamm R, Psarianos B, Mailaender T. Highway design and traffic safety engineering handbook; 1999.
 Ng JCW, Sayed T. Effect of geometric design consistency on road safety. Canadian Journal of Civil Engineering. 2004;31(2): 218-27. doi:10.1139/l03-090
 Cafiso S, Cava G, Montella A. Safety Index for Evaluation of Two-Lane Rural Highways. Transportation Research Record: Journal of the Transportation Research Board. 2007;2019: 136-45. doi:10.3141/2019-17
 Hassan Y. Highway Design Consistency: Refining the State of Knowledge and Practice. Transportation Research Record: Journal of the Transportation Research Board. 2004;1881: 63-71. doi:10.3141/1881-08
 Krammes RA, Brackett R, Shafer M, Ottesen J, Anderson I, Fink K, et al. Horizontal alignment design consistency for rural two-lane highways; 1995.
 Wang Y, Xu G, Bai H. Operating speed based alignment consistency evaluation using driving simulator: case studies from Taigan freeway in Jiangxi, China. Promet – Traffic & Transportation. 2013;25(1): 23-31. doi:10.7307/ptt.v25i1.1244
 Camacho-Torregrosa FJ, Pérez-Zuriaga AM, Campoy-Ungría JM, García-García A. New geometric design consistency model based on operating speed profiles for road safety evaluation. Accident Analysis & Prevention. 2013;61: 33-42. doi:10.1016/j.aap.2012.10.001
 Polus A, Mattar-Habib C. New Consistency Model for Rural Highways and Its Relationship to Safety. Journal of Transportation Engineering. 2004;130(3): 286-93. doi:10.1061/(ASCE)0733-947X(2004)130:3(286)
 Pérez-Zuriaga AM, Camacho-Torregrosa FJ, García A. Tangent-to-Curve Transition on Two-Lane Rural Roads Based on Continuous Speed Profiles. Journal of Transportation Engineering. 2013;139(11): 1048-57. doi:10.1061/(ASCE)TE.1943-5436.0000583
 Gipps PG. A behavioural car-following model for computer simulation. Transportation Research Part B: Methodological. 1981;15(2): 105-11.
 Sivanandam SN, Deepa SN. Introduction to Genetic Algorithms. Springer, Berlin, Germany; 2007.
 Sivanandam SN, Deepa SN. Introduction to Genetic Algorithms. Springer, Berlin, Germany; 2007. MathWorks I. Genetic Algorithm and Direct Search Toolbox for Use with MATLAB®: User's Guide: Math-Works; 2005.
 Vasconcelos L, Seco Á, Silva AB. Hybrid Calibration of Microscopic Simulation Models. In: Sousa JF, Rossi R, editors. Computer-based Modelling and Optimization in Transportation. Advances in Intelligent Systems and Computing. 262: Springer International Publishing; 2014. p. 307-20. doi:10.1007/978-3-319-04630-3_23
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).