Tandem Toll Booths for the Golden Gate Bridge

Many toll plazas are constrained in width by buildings or other physical barriers. These barriers may make the cost of adding toll lanes prohibitive. One method for increasing the capacity of a toll facility without increasing its width is to use tandem toll booths. A tandem toll booth consists of two toll takers in a single toll lane both serving alternating sets of vehicles simultaneously. The capacity of tandem toll booths is calculated with time-space diagrams and the cumulative headway distributions of vehicles at a conventional toll booth. The capacity depends on the maximum of two random variables, which correspond to the service times at the two booths, and is found by taking the product of their cumulative headway distributions. Adjacent tandem toll booths were found to increase the capacity of the Golden Gate Bridge toll plaza by about 15 percent, and batch tandem toll booths increase capacity by 25 percent or more. Thus, tandem toll booths would eliminate the queueing that now exists during the morning commute period without the cost of expanding the toll plaza's width.