Comparison study of the savings between a single and a double step toll systems

Solving the problem of highway congestion requires solutions that go beyond the capacity expansion of the roadway and towards effective capacity expansion though innovative operations of facilities. One such innovation is the implementation of congestion tolls in order to set volume levels at economically optimal levels. Transportation researches, for some time, have known the potential of congestion tolls as one solution to the congestion problem, and we are now seeing several cases of facilities operating under a congestion toll. However, essentially all of these cases operate under a single toll, i.e. the toll is fixed and does not change with volume level or any other operating condition. It is hypothesized that a variable toll could yield more efficient use of facilities, thus less congestion.;This research explores the efficiency gains associated with expansion of the congestion toll concept to include variable tolls. This is done first though a theoretical construct that formulates a quantity representing the economic gain associated with a variable toll scheme. A model that relates this economic gain to demand-side variables, supply-side variables, and exogenous variables is developed. The model is then used to conduct experiments yielding the economic gains with respect to these variables. Results of the experiments provide insight as to what conditions variable tolls would be feasible and what conditions they would likely not be feasible