Benefit Analysis for Urban Grade Separated Interchanges

Abstract

A procedure for evaluating the user benefits from highway improvement is demonstrated through a hypothetical case study. A comparison is made between an urban‐grade separated interchange and an at‐grade intersection in terms of the delay, vehicle operating cost, accidents, and vehicle emissions for several traffic demand levels. The results indicate that the urban‐grade separated interchange may be economically viable at an average daily demand as low as 40,000 total entering vehicles. Benefit cost ratios of 2.4 and 3.6 are generated with an initial average daily demand level of 80,000 total entering vehicles depending on the assumed traffic growth rate. A benefit/cost ratio of 2.9 is generated with an initial average daily demand of 60,000 total entering vehicles, assuming a 2.5 percent annual growth rate. Potential reductions in annual delay, fuel consumption, total vehicle emissions, and accident costs amounting to 73, 21, 40, and 80 percent, respectively, are indicated.