The cost effectiveness of high occupancy vehicle (HOV) lanes was analyzed by comparing the costs and benefits of existing HOV lanes with the hypothetical alternatives of doing nothing or adding a lane for general traffic. Three specific sites in the Seattle area were studied. A life-cycle costing approach was used.
The main result of the study was that (for the three locations studied) the construction of HOV lanes was the most cost effective alternative. The "marginal net present value" of each of the projects was positive (on order of $50 to $600 per commuter per year, depending on the specific comparison). The "marginal benefit/cost ratio" was greater than six for all cases.
Using extreme values for the elements of the model had little impact on the outcome of the study. Using extreme values for any factor, one at a time, did not come close to reversing any of the findings. Reversing the general finding of the study required extreme values for virtually all of the factors. It is extremely unlikely that all of the elements of the model were distorted in a direction to cause this outcome.
These findings showed that the three projects under consideration are very cost effective and should remain in place as HOV lanes. In fact, the investment of additional funds to improve the operation of these lanes could clearly be justified economically.
The methodology developed for this study was incorporated into an easy-to-use computer program that assesses the cost-effectiveness of the construction of HOV lanes in other locations. In order to save the costs of extensive data collection the sensitivity analysis approach developed in this study proved to be a valuable tool in the analysis of sites for HOV lanes. Instead of collecting extensive data to precisely quantify the cost-effectiveness of potential HOV lanes, this method can be used to determine which factors can significantly affect the outcome.