FREEWAY CONGESTION, RAMP METERING, AND TOLLS

The Cell Transmission Model (CTM) of a freeway with multiple origins and destinations is used to compare four schemes to reduce congestion in a freeway: (R) ramp control only; (T) one lane is tolled and ramps are uncontrolled; (B) bottlenecks are tolled and ramps are uncontrolled; (RB) ramps are controlled and bottlenecks are tolled. In the base case no ramps are metered and there are no tolls. It is found that (T) is inefficient and likely to leave all travelers worse off than in the base case; (R), (B) and (RB) can achieve efficient freeway utilization; (B) can eliminate queues, but has adverse spatial and equity side effects; (RB) minimizes these side effects. (RIB) is likely to be much less costly to implement and maintain than (T) or (B).