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.
