Regional Air Quality Conformity in Transportation

Authors: ManWo Ng Hong K Lo

Publish Date: 2013/04/05

Volume: 13, Issue: 4, Pages: 373-397

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Abstract

The air quality levels in various regions around the world remain a large public concern Transportation is known to be a major contributor to reduced air quality levels Until now the modeling of the regional impact of transportation on air quality has been based on the assumption of determinism On the other hand it is well recognized that transportation systems are subject to both demand and supply uncertainties In this paper we relax the assumption of determinism and allow for capacity and link flow uncertainty We introduce a probability measure – coined the conformity probability – to capture the full probabilistic behavior of vehicular emissions Moreover stochastic dependencies are modeled using copulas generalizing other commonly used dependence modeling techniques in the transportation network modeling arena In a case study we demonstrate that such a generalization is critical as the ranking of capacity expansion projects to improve air quality is shown to be dependent on the hypothesized dependence structure Finally we present some preliminary results that suggest that capacity uncertainty is more detrimental to the environment ie leads to lower conformity probabilities than demand uncertaintyThis study was sponsored by a grant from the US Department of Transportation to the TranLIVE University Transportation Center the Special Research Funding Initiative SRFI11EG15 and General Research Fund 617209 of the Hong Kong Research Grants CouncilSince fracv ac 1c 2l ayle 0 and y ≥ v a c 1 c 2 l a exp 1 the Lambert Wfunction will return two real values cf Definition 1 If v a c 1 c 2 l a exp 1 y ≤ K a we have the solutions frac1c 2W 0leftfracv ac 1c 2l ayright and frac1c 2W 1leftfracv ac 1c 2l ayright However if y K a there is only one solution since we must have s a  ≤ l a /t a f cf Fig 3 This solution will be given by the smaller of the above solutions which is frac1c 2W 0leftfracv ac 1c 2l ayright QED

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