Modeling Violations in High-Occupancy Toll Lane Studies

States are increasingly looking to high occupancy toll (HOT) lane facilities to improve mobility and reduce congestion for travelers and shippers using the nation’s freeway corridors. While continuous access to HOV lanes is standard practice, due to existing toll collection technologies, access to HOT lanes must be more limited. Physical barriers in the form of concrete barricades or plastic pylons, for example, are often constructed to ensure compliance with rules for accessing HOT lanes. Increasingly, however, nonbarrier separation techniques are employed for this purpose. Such techniques may be used where the necessary space required for physical barrier separation and police activities required for enforcement is limited or construction and maintenance costs of such barriers is prohibitive. Nonbarrier separation methods, as a result, have become more common. Nonbarrier separation methods, however, permit nearly unlimited improper ingress/egress to/from the managed lanes. These violations impact free-flow speeds of both managed and general purpose lanes. Additionally, violations have a negative impact on revenue. Even with significant enforcement, violation rates related to non-barrier separated managed lanes in the U.S. are considerable. Despite this, no prior model developed for the purpose of predicting improvements in travel speeds and other traffic performance metrics and the potential revenue that can be raised through the introduction of a new HOT lane facility within an existing roadway or to assess potential practicable operational strategies and facility designs has incorporated this violation behavior. This research effort will seek to assess the importance of this omission. Specifically, the proposed research effort will quantify the impact of the various types of violations associated with HOT lanes on estimates of travel speeds and other traffic metrics obtained through simulation modeling of proposed HOT lane facility designs and determine the criticality of modeling such violations in conducting studies of proposed HOT lane facilities.