Do Freeway Traffic Management Strategies Exacerbate Urban Sprawl?: The Case of Ramp Metering

The impact of highway capacity expansion on urban land use has been studied extensively. With the shift of transportation investment priorities from major capacity expansion projects to operational improvements, it has become increasingly important to understand the impact of transportation control measures such as traffic management and pricing on location choices. This paper explores the impact of traffic management strategies on land use patterns using the example of ramp metering. A regression-based transportation model is employed to capture changes in accessibility due to ramp metering on a highway network. A land use change indicator model then estimates how employment and residential density distributions shift in response to changing accessibility in several stylized urban areas with various initial land use patterns (e.g., monocentric and polycentric cities). Ramp metering is shown to improve accessibility in a nonuniform fashion. The resulting land use changes depend on the existing land use conditions. In monocentric cities, ramp metering exacerbates urban sprawl by encouraging residents to live further away from their workplaces, which produces avoidable excess travel. In polycentric cities with both nondominant central business districts and secondary employment centers, ramp metering actually encourages residents to relocate to areas near existing employment centers and therefore serves as an antisprawl measure. The weakest impact of ramp metering on land use is observed when an urban area has a perfect job-housing balance. Other interesting findings suggest that by making downtown areas more accessible, ramp metering may help revitalize declining city centers in congested cities and that business location decisions are not significantly affected by ramp metering.