Abstract
The value of travel time savings (VOT) has been an important theme in transportation research because travel time savings is the single largest contributor to the benefits of many transportation projects. It also plays a central role in the cost benefit analysis of the size and scope of public investment. It can shed important light as to whether congestion pricing schemes can increase social welfare. The disagregate models which are used to derive VOT help us gain insight as to how commuters make their travel decisions. The San Diego I-15 Congestion Pricing Project allows the use of High Occupancy Vehicle lanes by solo drivers for a toll. The toll adjusts every six minutes to maintain free flowing traffic on the High Occupancy/Toll (HOT) lane. Carpoolers get to use the lane for free. This presents us with a unique opportunity to study commuters’ choice of a tolled and uncongested alternative versus a free and congested alternative. This thesis studies this decision process based on not only what the commuters say they would do but also on what they actually did. The general result is that the HOT lane is used more by high income, middle aged, homeowners and female commuters. Increased travel time savings and reduced uncertainty in travel time encourages the use of HOT lane. Commuters are more sensitive to variations in travel time in the morning peak than in the afternoon. The toll acts both as a cost of travel and signal of congestion. If the actual toll rises above what the commuter expects then she is more likely to take the lane. The effect of toll also depends on the level of uncertainty in travel times. VOT estimates from Stated Preference data (based on hypothetical responses) are significantly lower than those based on Revealed Preference data (from observed behavior on SDCPP). The difference is consistent and persistent across the different models and methodologies pursued in this thesis. This leads to the conclusion that these differences are real and reflects the difference in responses of individuals to actual and hypothetical situations.