Modifying a high occupancy vehicle (HOV) lane to a high occupancy/toll (HOT) lane generally involves allowing single occupant vehicles (SOVs) to travel on the free-flow (HOV) lane for a toll. This may entice some former transit riders to pay the toll to obtain the benefits of traveling in their own vehicle on the HOV lane. Thus, the introduction of a HOT lane has the potential to impact transit ridership, dramatically lowering the average vehicle occupancy (AVO) of the lane. To investigate this potential problem, surveys were distributed to park-and-ride bus passengers on two Houston freeway corridors. Passengers responses to questions regarding their trip characteristics, their socio-economic characteristics, and stated preference scenarios were used to develop a mode choice model. Scenarios with varying tolls and travel time savings were simulated using this model. For all scenarios, only a small percentage of transit passengers chose to switch to driving alone on the HOT lane. Transit passengers shifting to SOV on the HOT lane reduced average vehicle occupancy only about 1 percent to 2 percent. SOV drivers shifting from the general purpose lanes to the HOT lanes are likely to affect AVO much more. However, as long as free-flow conditions are maintained, this analysis shows that the HOV lane can be successfully adapted to a HOT lane and move more people, even if a few transit passengers choose to drive alone.
Abstract