HOT Lane Policies and Their Implications

High-Occupancy toll (HOT) lanes allow lower-occupant vehicles (LOVs) to use a HOV lane for a fee, while maintaining free travel to qualifying HOVs. HOT lanes are gaining interest throughout the country as a strategy for meeting multiple performance objectives in congested urban freeway corridors. Currently there are ten fully operational HOT lanes around the country in seven different states and this research examined the nine of them (excluding I-35 W). Even with only a handful of operational HOT lane projects, there is great diversity in terms of HOT lane design and operations. With HOT lane implementation there are many issues, including: toll rates, vehicle occupancy requirement, number of access points, and safety. This research examined (i) the different factors which lead to the development of the HOT lanes in their respective corridors (ii) the objectives of the HOT lanes (iii) changes made in the corridor due to HOT lane implementation (iv) the different impacts of the HOT lanes and (v) the extent to which the objectives of the HOT lanes were achieved. Using three pairs of HOT lanes with similar design and operational characteristics, comparisons were made to examine the impacts of the similar HOT lanes in two different corridors. With the strict registration requirement for HOV3+ on the I-95 Express Lanes there were indications that some carpoolers broke up in to lower occupancy vehicles. Tolled access for HOV2s on I-95 as well as the SR 91 Express Lanes resulted in lower usage of the Express Lanes by the HOV2s (fewer than 30 percent of the total corridor HOV2s) as compared to a conventional HOV lane (60 percent) where HOV2 access is free. The effect of availability of transit on the HOT lanes can also be seen from SR 91 as compared to I-95. On SR 91, the Express bus does not use the Express Lanes and there was almost no change in its ridership after the Express Lanes were implemented. However, on I-95, the Express bus uses the Express Lanes and travel time of buses decreased by 17 minutes due to Express Lanes implementation. The Express bus ridership also increased by 30 percent. On the SR167 and I-25 HOT lanes, the exogenous factors like gas prices and economic recession seemed to influence the usage of the HOT lanes. In both the HOT Lanes, carpool usage was positively correlated to the gasoline prices. On I-25, the increasing unemployment rate coincided with the decreasing toll paying travelers. On SR 167 there were also indications of mode shifts among the transit, carpool and toll paying SOVs due to fluctuating gas prices. With declining gas prices, the transit and carpool usage went down while toll paying users increased. An inverse relationship between the convenience of access points and the safety perceived by the HOT lane users was found. For example, I-15 Express Lanes in Salt Lake City reduced the access points from unrestricted with the previous HOV lanes to limited with the Express Lanes. As a result, more predictable merging led to an increase in the perceived safety of the Express lanes as well as the speed of the corridor. On the other hand, some carpoolers mentioned not using the Express Lanes anymore because of access inconvenience. The access inconvenience was also mentioned by previous carpoolers in HOV lanes on I-95 as one of the reasons for not using the Express Lanes. These findings underscore the importance of outreach programs during the planning process of the HOT lanes to minimize the confusion among the previous users of the HOV lanes and spreading awareness among them regarding the increased safety benefits.