An examination of factors affecting high occupancy/toll lane demand

In recent years, high occupancy/toll (HOT) lanes have gained increasing recognition as a potential method of managing traffic congestion. HOT lanes combine pricing and vehicle occupancy restrictions to optimize the demand for high occupancy vehicle (HOV) lanes. Besides having all the advantages of traditional HOV lanes, HOT lanes can also generate revenue to help finance various operation and maintenance programs. At present there are four fairly well established HOT lane projects in the United States: two in Houston, Texas, and one each in San Diego, and Riverside County, California. After 6 years in operation, Houston's HOT lanes receive comparatively lower patronage than the two California projects. An understanding of why people choose to use HOT lanes will be vital to improving the performance of existing HOT facilities and will also shed light on policy decisions regarding future HOT lane investments. This study examined the relative importance of different parameters which could be expected to influence the demand for HOT lanes using standard statistical and discrete choice modeling techniques on survey data from Houston's HOT lane users. The study showed that, controlling for other variables, trip length, the driver's perception of travel time savings offered by the HOT lanes, frequency of travel in the freeway corridor, trip purpose, and the amount of time spent on carpool formation were good predictors of HOT lane usage. Socioeconomic characteristics such as age and level of education were also good indicators of the frequency of HOT lane usage whereas household size, occupation, and hourly wage rate were not. Gender and annual household income were only loosely related to HOT lane usage. Inelastic responses to minor changes in the toll coupled by responses to a question regarding participants feeling towards the $2.00 toll, suggested that the toll was not a major deterrent to HOT lane usage. A primary deterrent was the need for one passenger to use the HOT lane when free use required two passengers. However, travelers who shared the toll with their carpool partners were likely to have made more frequent HOT lane trips than those who bore the entire cost.