High‐Occupancy Vehicle Modeling Technique

Construction of Boston's 4.4‐billion dollar Central Artery/Third Harbor Tunnel project will begin in the near future, with completion scheduled for the late 1990s. The project's expected significant impact on the regional transportation system provided the impetus for a comprehensive planning effort that included the development of regional high‐occupancy‐vehicle (HOV) planning tools. As the project moves toward preliminary engineering and design, the basic sketch planning tools used earlier in the planning process are no longer adequate. Therefore, a modeling process has been developed to estimate modal vehicle trip tables, and then, using a fairly new feature of the Urban Transportation Planning System (UTPS) assignment program UROAD, assign each sequentially to highway networks containing alternative HOV system configurations. This process also allows the designation of facilities with different criteria for priority eligibility: Taxis, for example, may be allowed on some priority facilities, but not others. This effort results in estimated volumes by mode for each link in the system, allowing detailed evaluation and design of HOV lane and ramp facilities.