Effect of geometric design consistency on road safety

• Published in: Canadian journal of civil engineering Vol. 31; no. 2; pp. 218 - 227
• Main Authors: Ng, Joanne C.W, Sayed, Tarek
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.04.2004; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Applied sciences; Buildings. Public works; Computation methods. Tables. Charts; Design engineering; Exact sciences and technology; Geometry; Ground, air and sea transportation, marine construction; Highways; Prediction models; Project management. Process of design; Road transportation and traffic; Road types (roads, freeways, express ways, etc.); Roads; Roads & highways; Safety engineering; Structural analysis. Stresses; Traffic accidents & safety; Transportation infrastructure; Vehicle stability; Structural design; Speed; Traffic accident; Forecast model; Modeling; Recommendation; Design; Traffic safety; Freeway; Rural area; Qualitative analysis; Geometrical method; Road traffic; Uniformity; Quantitative analysis
• ISSN: 0315-1468; 1208-6029
• DOI: 10.1139/l03-090

Geometric design consistency is emerging as an important rule in highway design. Identifying and treating any inconsistency on a highway can significantly improve its safety performance. Considerable research has been undertaken to explore this concept including identifying potential consistency measures and developing models to estimate them. However, little work has been carried out to quantify the safety benefits of geometric design consistency. The objectives of this study are to investigate and quantify the relationship between design consistency and road safety. A comprehensive accident and geometric design database of two-lane rural highways is used to investigate the effect of several design consistency measures on road safety. Several accident prediction models that incorporate design consistency measures are developed. The generalized linear regression approach is used for model development. The models can be used as a quantitative tool for the evaluation of the impact of design consistency on road safety. An application is presented where the ability of accident prediction models that incorporate design consistency measures is compared with those that rely on geometric design characteristics. It is found that models that explicitly consider design consistency may identify the inconsistencies more effectively and reflect the resulting impacts on safety more accurately than those that do not.Key words: geometric design consistency, road safety, quantification, accident prediction models.