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Journal of Advanced Transportation
Volume 2017 (2017), Article ID 5612849, 12 pages
Research Article

Reliability-Based Analysis of Sight Distance Modelling for Traffic Safety

1Departamento de Ingeniería Civil: Transporte y Territorio, Technical University of Madrid (UPM), Madrid, Spain
2Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, BC, Canada V6T 1Z4

Correspondence should be addressed to C├ęsar de Santos-Berbel

Received 6 March 2017; Revised 20 April 2017; Accepted 3 May 2017; Published 31 May 2017

Academic Editor: Alexandre G. De Barros

Copyright © 2017 César de Santos-Berbel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Sight distance is of the utmost importance for traffic safety. The consideration of three-dimensional (3D) available sight distance (ASD) in geometric design has been supported by several researchers. However, existing ASD estimation methods are two-dimensional (2D) in nature, which do not evaluate varying visibility conditions. This paper compares different methodologies of modelling the ASD. The ASD of 402 horizontal curves, located in twelve in-service two-lane rural highways, was analyzed. Three ASD estimation methods were used which include a 2D method and two different 3D methods. The ASD results obtained through 2D and 3D methodologies are compared. Also, the different conditions of the existing roadside features or geometric elements, under which the 3D ASD estimation is important, were identified. Next, reliability theory is utilized to evaluate the risk level (probability of noncompliance, ) associated with limited sight distance for each ASD modelling method. The results of the comparison emphasized the importance of considering the 3D modelled sight distance when evaluating the associated risk either in highway design or during the service life. In addition, the results indicated that the ASD modelling approach can have a significant impact on the estimation of the safety of highway design.