Analysis and design of tradable credit schemes under uncertainty

Market-based instruments for congestion mitigation can be generally classified into two groups: price-based and quantity-based. The former, widely known as congestion pricing, charges tolls to influence travelers' decisions; the latter directly regulates congestion. More specifically, credits or permits are first distributed by a government agency, and travelers are then required to pay a certain number of credits to access transportation facilities. The credits can be traded between travelers, and the price is determined by the market through free trading. In this study the identity between congestion pricing and tradable credit schemes in managing network mobility is formally established. A numerical example demonstrates how the identity falls apart when uncertainty is associated with transportation supply or demand. A sensitivity analysis of the coupled network and market equilibrium is then conducted to predict how credit price varies with respect to the perturbation associated with the supply or demand. A safety-valve policy is investigated to balance regulation success and price volatility under uncertainty.