Quantification of Possible Impacts of Capacity Expansion Projects on Transportation Costs via Trip-based Full Marginal Cost Estimation Methodology

250 Word count: 5255 Text + 5 Tables + 3 Figures = 7255 Resubmission Date: November 15, 2007 Paper accepted for Presentation and Publication in the Transportation Research Record, Journal of Transportation Research Board after being presented Transportation Research Board’s 87 Annual Meeting, Washington, D.C., 2008 TRB 2008 Annual Meeting CD-ROM Paper revised from original submittal. 2 ABSTRACT This paper evaluates the impacts of proposed capacity expansions on the full trip-costs on large transportation networks such as Northern New Jersey. Unlike most previous studies, considering link-based measures only, this study focuses on individual trips to estimate the shortterm changes in full marginal costs (FMC). Trips between each origin-destination (O-D) pair are represented as paths determined via a novel constrained k shortest-path algorithm developed as part of the proposed methodology. Road sections are selected as candidates for capacity expansion based on the FMCs obtained for the whole network, i.e., road sections with highest FMC values are selected. Proposed approach for the before-and-after analysis is illustrated using four road sections (State-Highway (SR) 18, SR-17, SR-3, and Garden State Parkway (GSP)). Transportation costs calculated for before-and-after the capacity expansion and their fitted distributions show that trip-cost between a given O-D pair is not constant; rather it follows a probability distribution whose shape is affected by the road characteristics such as road and area types and number of lanes among other factors. Calculated costs at different probability levels show that highest reductions in the FMC are observed along SR-3 and GSP. Cumulative change in the FMCs of these segments is less than 20% with a probability of 0.95 and less than 15% with a probability of 0.5. This type of analysis gives a different and unique insight to policy planners regarding quantification of transportation costs in worst and best cases, and identification of projects that are most likely to generate highest benefits. TRB 2008 Annual Meeting CD-ROM Paper revised from original submittal.