Efficiency and equity of ramp control and capacity allocation mechanisms in a freeway corridor

This paper investigates the efficiency and equity of morning peak ramp control schemes in a freeway corridor with limited capacity. In terms of efficiency, both short‐run and long‐run optimal ramp control schemes are obtained by minimizing the total travel cost and maximizing the total social benefit along the corridor. It is found that for a short‐run optimum with inelastic demand, the morning peak period is of the same duration for different on‐ramp locations. But for a long‐run optimum with elastic demand, the peak duration for various on‐ramps increases with the local capacity elasticity of demand. In terms of equity, two measures are defined from a demand‐based viewpoint and a space‐based viewpoint. It is shown that the short‐run optimal ramp control scheme is perfectly fair from a demand‐based equity viewpoint. Consequently, two typical ramp control schemes–a perfect demand‐based equity scheme and a perfect space‐based equity scheme–are introduced and compared with the long‐run optimal ramp control scheme in terms of efficiency and equity. Numerical simulations using survey data from China suggest that the perfect demand‐based equity scheme attains an economic welfare level that is very close to the optimal one and the conflict between efficiency and equity diminishes as demand becomes less elastic.