A COST ANALYSIS OF HIGHWAY DESIGN AND CONSTRUCTION ALTERNATIVES

A model was constructed to calculate the total present value of the construction, maintenance and upgrading costs of a highway section. This model was used to find the costs of providing roading in each of a range of traffic and policy situations. Comparision of least cost construction sequences between situations enabled preferred construction and expansion sequences and materials as well as the sensitivity of cost to the various parameters to be found. The basic results are (1) a low discount rate and a 20 year planning period should be used in design, (2) initial traffic on a road is critical to cost and should be carefully estimated, traffic growth is of less importance, (3) as few lanes as possible should be provided, (4) initial pavement thickness should be sufficient to carry 20 years load. The policy conclusions that emerged are (1) flexible granular pavement should be used, not rigid bitumen pavement, (2) the legal maximum axle load can be increased without causing a significant increase in road costs. /AUTHOR/