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Some of the basic terms that will be used in the chapters to come have been
discussed in this section.
Following are the terms and their definitions:
- Throughput: It is the number of vehicles passing through the toll plaza
over a short period of time, usually 1 hour.
- Demand: It is the sum of throughput and the number of vehicles queued
up at the toll plaza during 1 hour.
- Processing Time: It is the difference between the time a vehicle leaves
and the time when it enters the toll area.
The entry time is taken from the moment a vehicle stops in the queue.
- Queueing Area: It is the area of the toll plaza where the number
of lanes of incoming vehicles increase from the number of lanes on highway
to the number of tollbooths.
The vehicles queue up in this area to make the toll payment.
Fig. 1 shows the location of queueing area in a toll
plaza.
- Merging Area: It is the area of the toll plaza where the number
of lanes of outgoing vehicles decrease from the number of tollbooths to the
number of lanes on highway.
The vehicles have to merge with other vehicles in this area before the highway
comes to its normal width.
Fig. 1 shows the location of merging area in a toll
plaza.
- Optimal Toll Plaza Configuration: It is the one which minimizes the
expected time a driver must spend while travelling through the system.
Figure 1:
Toll Plaza Geometry
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