Toll Roads: To Charge a Lot or a Little?

Most often we think of road tolls as a nuisance while driving but according to the Netherland Organisation for Scientific Research there is far more thinking about tolls going on than just that.

Tolls and the regulation of the various toll charges are part of a larger problem faced by national and local governments. The factors that play a role in the problem are (1) the need for government to minimize harmful environmental effects of travel, (2) and to minimize total travel time of all travelers, (3) the need to maximize toll incomes (4) travelers' desires to make journeys quickly and cheaply.

These considerations lead to a complex model in which the various variables are dependent on each other. Dr. Dusica Joksimovic, who now works in Transport Planning at the Delft University of Technology, designed an instrument during her doctoral research that can provide governmental policy makers with a quicker insight into the outcomes of policy measures, thus enabling them to more appropriately choose policy which will optimize the possibilities for successfully meeting all the variables.

The instrument Joksimovic developed is a simulation model that predicts where, when and how much toll must be charged to attain the desired policy outcomes. Possible policy outcomes are commensurate with the above listed variables, for instance, desired outcomes might be to decrease harmful environmental effects, reduce total travel time for all travelers or maximize toll revenues.

Joksimovic's model works through iterative, or repetitive, calculations of the impact of traffic data on road congestion and the total tolls. From these calculations, the model searches for an optimal composition of the toll charge.

Tolls--a fee payed for the right to enter or exist a road, bridge or tunnel--are a source of revenue for local and national governments and are used for particular road related purposes. They are frequently used for maintenance and repair. They may also be used to raise funding for repayment of revenue bonds previously used for construction or operation costs.

Toll roads actually have a long history. For example, references to toll roads in Arabia and Asia are found in Aristotle's writing. Toll roads are noted by Arthasastra as being present in India in the 4th century B. C. Early Germanic tribes restricted use of mountain passes through the imposition of tolls. During the reign of the Holy Roman Empire in the 14th and 15th centuries, toll roads were in use.

Among the variables relevant to the calculations performed by Joksimovic's model are the different characteristics of travelers. For instance, people who want to reach a destination and those who want to travel as cheaply as possible and are flexible with respect to their arrival time have different attitudes and inclinations toward paying high tolls.

The models iterative calculations have shown that a flexible toll charging system in which car drivers must pay more at peak travel times than during off-peak times leads to fewer traffic jams, which reduces travelers' journey time and may produce a lessened negative environmental impact. A flexible toll charging schedule also produces maximum toll incomes.

"Toll charges reduce travel time," Netherlands Organisation for Scientific Research.

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