Re-evaluating superelevation in relation to drainage requirements and vehicle dynamics

Abstract

There is a growing public demand for safer streets and highways. Designing safer roads requires a need to review and improve the existing design guidelines. Road widening and general roadway rehabilitation projects are designed according to the existing roadway conditions. As a result, drainage problems associated with superelevation are prevalent. An evaluation of design alternatives in terms of safety, taking into consideration the superelevation values in relation to the drainage requirements and vehicle dynamics, will prolong the design process. However, it is believed that the additional time invested will result in safer roads and a reduction in vehicular accidents and in addition a potential in lower construction costs. This latter benefit is derived by limiting instances where a design component is overdesigned. The objectives of this paper is to (1) develop drainage criteria for flow paths and depths on road surfaces due to superelevation, (2) analyse the speed and vehicle dynamics at sharp or reduced horizontal curves, (3) develop superelevation criteria for steep longitudinal grades on sharp horizontal curves by identifying and analyzing associated drainage problems and (4) present an overview of an independent software tool to assist geometric designers and authorities in the civil engineering industry to design ‘safe’ roads from a geometric design viewpoint by taking factors such as time, cost, quality and context-sensitive design solutions into consideration. The paper draws from an innovative desktop literature analysis study and presents an overview of the research objectives. The desktop study is complemented by the analyses of data from user and stakeholder samples conducted on a section identified on National Route 3.