Hazard-Based Analysis of Highway Project Development Times

Abstract

Transport agencies around the world recognize the importance of on-time on-budget delivery of highway projects and understand the need for an efficient transport development process. Past studies of highway project duration and cost estimation were focused on construction, and few studies have focused on preconstruction project delivery from an agency’s perspective. This paper proposes the use of hazard-based duration models for investigating the potential risk factors that could affect project development time from planning to letting. A database containing over 35 years of highway project data from the state of Indiana was used to develop appropriate models. Of the three model forms (Weibull, Weibull with gamma heterogeneity, and log-logistic) considered in the paper, it was found that the log-logistic model is the most appropriate for modeling project development time. For each work category (pavement, bridge, and road/interchange projects), risk factors were identified, and their influences on project development time (and consequently, on letting time) were investigated. The developed hazard-based duration models were further applied to demonstrate their ability to predict expected project development time for delivery and the project-related factors that influence this duration, thereby providing the agency with a useful interpretation of associated delivery risks.