A Framework for Optimal Highway Capacity Expansion Decision-Making

Abstract

Transportation facilities besides providing mobility and accessibility for people and goods also play an important role in economic vitality and global competitiveness of any nation. The involvement of enormous investments in highway development necessitates the exigency of economic analysis and modeling techniques before any decision could be implemented. In Pakistan highway expansion and/or construction decisions are mostly politically influenced and are implemented without any detailed engineering economic analysis techniques. Present study developed a comprehensive framework for determining optimal time for highway capacity expansion based on detailed engineering economic analysis duly incorporating user and agency cost components. The development of framework was based upon the annualized widening costs (agency lane addition cost and workzone user delay cost) and excessive user costs for do-nothing scenario (excessive travel delay cost, excessive VOC and excessive crash cost) for each analysis year within highway life cycle. The breakeven point between two cost categories was determined as the optimal time for highway capacity expansion intervention. A segment of Islamabad Highway from Airport Chowk to the intersection of Islamabad Highway with Grand Trunk road was selected for case study. The case study results revealed an ADT ranging from 34430 to 37600 as optimal for initiating widening intervention of 4-lanes to 8-lanes divided highway. Furthermore, sensitivity analysis was conducted to evaluate the magnitude and direction of influence of varying weights of agency to user cost, annual traffic growth rate and annual interest rate on optimal time range for highway capacity expansion. The proposed framework provides a comprehensive insight about highway capacity expansion decision making and it is anticipated that study results if applied by national highway agencies shall result in saving huge amount of needless agency expenditures and excessive user costs.