The impact of HOT lanes on carpools

Carpooling on eight roadways with HOT lanes was examined. As best as possible, data on the number of carpools on the facility in the year before and the year after converting from HOV lanes to HOT lanes was examined. Overall, carpooling decreased on most of the corridors, stayed the same on a couple of corridors, and on the one corridor that added the HOT lanes (SR-91) carpooling increased. Despite these results it is still difficult to draw definitive conclusions as (a) carpool preference tends to vary by facility, (b) there were many exogenous factors also playing a role in the amount of carpooling, (c) there is inherent difficulty obtaining occupancy counts and those counts can fluctuate a great deal day to day and month to month. Overall though, it does appear that carpooling is often negatively impacted by converting a HOV lane to a HOT lane.