Risk ranking on existing two-lane rural roads with respect to alignment and at grade intersections

Vassilios Matragos, Stergios Mavromatis, Konstantinos Apostoleris, Basil Psarianos

Last modified: 2023-06-05

Abstract


The objective of this paper is the elaboration of a suitable methodology capable of deploying elements that characterize the existing infrastructure on two-lane rural roads, regarding road geometric elements (horizontal and vertical alignment, superelevation, sight distance), as well as location and geometric elements of intersections with the scope to evaluate the built-in road safety. The overall target is the utilization of these elements to lead to evaluation coefficients that point out the risk level of the examined road sections, as well as the critical areas, in terms of safety levels, curved sections and intersections.
In this context, a hierarchy of critical parameters affecting the risk rating of a road network with respect to geometric design and at-grade intersections was primarily carried out. Appropriate mathematical equations were created for each parameter, based on current road design guidelines and the corresponding Crash Reduction Factors (CRF) presented in the literature.
Initially, case studies were conducted, out of which special diagrams were produced to assess the risk level of each parameter. Subsequently, a basic statistical analysis of the results was carried out , using regression factors aiming at developing an appropriate mathematical model for the estimation of the risk level. The same analysis was performed for each parameter separately and appropriate weight coefficients were sought in order to obtain a combined rating that characterizes each road section, while at the same time identifies those critical intersections that present high probability of accident occurrence.
Finally, data were collected from a significant sample of the existing two-lane road network of Greece, about 1000km of road network with more than 4000 intersections (unpaved road intersections were also included), in order to assess the results of the proposed methodology.

Keywords


at-grade intersections; risk ranking; road geometric design

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