Estimation of Highway Project Duration at the Planning Stage and Analysis of Risk Factors Leading To Time Overrun

Abstract

Estimation of time duration of highway projects at the planning stage serves as a vital input for construction planning, scheduling and contract administration. However time overrun, resulting from various factors is the most cardinal issue which eventually leads to cost overrun and hence induces turbulence in the initial cost and time estimates. In this research, highway project duration is estimated on the basis of variables such as planned cost and project type which are known at the planning phase. Data comprises of project types such as pavement construction, improvement, rehabilitation and bridge construction projects of National Highway Authority, Pakistan. A mathematical relationship between highway project duration, planned cost and project type is demonstrated in this research by using various model specifications. Furthermore using multivariate regression analysis correlation of the time overrun with potential risk factors is investigated encompassing attributes such as project type, cost and geographical location. Probability plots are also generated by survivor function in log logistic analysis which provide the likelihood of the project duration being equal or greater than some specified duration. The research identifies a number of significant risk variables and their severity that contributes to the extensive delays and consequently exceeds the planned time estimates. Late funds release from to the funding agencies, land acquisition problems and cash flow problems within NHA were the chief time overrun factors prevailing in most of project across the country. The models developed can assist the project administrators in determining improved estimates of project duration and enhancing the expected delay estimation in completion time of planned projects.