Quantcast Traffic Considerations

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future pavement overlays, a minimum vertical clearance of 5.2 meters (17 ft.) will be
maintained throughout the ECF.
4.3 Traffic Considerations
The effect of an entry control facility design on the surrounding roadways and intersections is
of paramount concern. If congestion occurs, and there is inadequate stacking distance the
queues may extend into adjacent intersections or cause congestion on feeder roads.
Additionally, the stopped vehicles become a target of opportunity themselves. Reference 2
suggests the access control zone should ideally be a minimum of 100 meters (300 feet) from
any intersection, however, in many cases this may not be possible. The design of a
modification or renovation of an existing ECF should improve the throughput of the ECF, and
as a minimum not reduce the throughput.
4.3.1 Capacity
The design capacity is based on the peak hour traffic volume that the entry control point
would handle without unreasonable congestion. The design should consider both current and
future traffic demands, where the design demand is the peak hour traffic volume, such as the
morning rush hour. If the rate of vehicles arriving at an entry control facility exceeds the rate
of processing, then congestion will occur (2). As discussed in Section 2.3, the FPCON has a
great effect on the processing time per vehicle and the traffic volume due to changes in the
inspection procedures and the number of authorized vehicles. The traffic design of the ECF
will consider the operations at all FPCONs. However, since some disruption in the level of
service is expected at high FPCON(s) (Charlie or Delta), the traffic impacts will be designed
based on the elimination of congestion at FPCON Bravo and below. At FPCON Charlie and
Delta, some congestion may occur but this is sometimes offset by the installation also reducing
the population seeking to enter the installation to mission essential personnel only during
FPCON Charlie or Delta. The congestion during FPCON Charlie or Delta should be minimized
where possible.
If the final capacity achieved at an entry control point is below the expected peak hour
traffic volume, congestion can also be reduced by implementing staggered work hours,
encouraging carpooling, adding lanes, and/or tandem processing (multiple identification
checks per lane) (2). It has been estimated that tandem processing may improve capacity by
up to 25% per lane (2). Therefore as a minimum, all entry control points shall be designed to
support tandem processing. It may also be possible to design lanes to be reversible such that
outbound lanes can be used for incoming traffic during periods of peak volume. However,
priority should be given to maximizing the number of lanes prior to utilizing reversible lanes.
4.3.2 Adequate Lanes
The number of lanes planned for an entry control point shall be sufficient to handle the
expected volume of traffic, especially during times of peak demand such as morning rush
hour. If necessary and possible, increase the number of lanes to increase the throughput of
the entry control point. To aid in the determination of the required number of lanes, Table
4-1 provides reference information concerning the approximate throughput of entry control
points during different levels of identification.
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