Urban areas in the U.S. have grown at a fast pace in the last several decades. Many attribute the sprawling land use development pattern to the construction and expansion of limited access freeways, which initially greatly improved urban mobility but have since experienced deteriorating level of service. Urban traffic congestion is a serious and continuously growing problem in many cities [1]. It is now widely acknowledged that we cannot build our way out of congestion due to induced demand, increasing land acquisition and construction costs, and public oppositions to more freeways. A recent study [2] finds that 1,150 lane-miles of new freeways would be required in the next twenty years to maintain uncongested traffic flows in the Twin Cities, Minnesota. That represents a 70% expansion of the existing freeway system in the Twin Cities, and an obviously impractical investment scenario. Most U.S. cities are employing a variety of transportation management, multimodal, and to a lesser extent pricing strategies to maintain/improve urban mobility and accessibility, in addition to freeway capacity expansion.
Land use and transportation decision-makers across the nation are facing a freeway capacity expansion dilemma. Conventional wisdom appears to suggest that some freeway capacity expansion is necessary to cope with congestion, even when land use and travel demand management strategies are present. The reality tells a different story: no city has been able to build its way out of congestion. As new freeway capacity attracts even more traffic, gridlock persists and any subsequent attempt to build more capacity just becomes increasingly more difficult. Having learned hard lessons in the past, recently several large urban areas with serious congestion problems such as Los Angeles and Boston have proposed strict no-more-freeway policies, which could effectively remove freeway capacity expansion from the transportation investment picture.
These observations of the various limitations of freeway capacity expansion have led to a provocative planning and policy question – What if we completely stop building additional freeway capacity. From a theoretical perspective, as a freeway network matures, there should exist a saturation point beyond which any additional freeway capacity would only be counterproductive, and worsen the existing urban transportation problems. Traditional benefit/cost analysis of individual freeway capacity expansion projects often ignores long-term induced demand and land use changes, and therefore does not represent a systems approach to this important theoretical issue. From a practical perspective, a no-more-freeway policy can relieve transportation funds for other potentially more effective usages, such as improving urban arterial streets, improving transit level of service and coverage, implementing demand manage and/or pricing strategies, and facilitating more efficient land use patterns (e.g. high density in-fill and transit-oriented developments).
This research aims to answer the following critical land use-transportation planning questions:
(1). Under what conditions will freeway capacity expansion become counterproductive to urban planning goals (where is the saturation point and are we there yet)?
(2). How would urban land use and transportation dynamics evolve if an investment policy prohibiting all freeway capacity expansions was implemented (i.e. no-more-freeway).
(3). What would be the implications of such a policy on mobility, accessibility, land use pattern, transportation finance, and social welfare?
Improved knowledge on these issues should benefit planers and decision-makers who pursue mobility and sustainability objectives and have the power to shape future cities. The general public will also benefit from more informed transportation investment decisions. The proposed research builds upon an integrated modeling tool developed by the P.I. in previous research projects funded by NSF [3] and OTREC [4],– ABSOLUTE (Agent-Based Simulator Of Land Use-Transportation Evolution) – which translates planning policies such as the “no-more-freeway” policy into alternative urban growth paths and possibly urban growth equilibria. Due to the “Small Start” (i.e. one-year, relatively low budget) nature of this proposed project, the analysis will only be conducted in stylized urban areas. Empirical analysis of the “no-more-freeway” policy in real-world cities will be pursued in future research.
