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 4.2.4.1
Channelization Islands
Channelization islands provide a safe position for security personnel and serve as a location
to install present or future access control devices. A primary channelization island will be
provided between each incoming and outbound traffic lane in the access control zone. The
island is required in the outbound lanes due to security regulations that may periodically
require the inspection of exiting vehicles and also due to the potential for automated access
control, which may be used to monitor and identify exiting vehicles. The minimum primary
channelization island will be 914 mm (3 feet) in width, 160 mm (6 inches) in height and 15.2
meters (50 feet) long. A secondary channelization island will be provided prior to the first
rejection point in the access control zone. This island will support potential future automated
access control systems. The secondary island will be a minimum of 914 mm (3 feet) in width,
160 mm (6 inches) in height and a length of 3 meters (10 feet).
4.2.4.2
Median
As discussed in Reference 9, medians are constructed to:
Separate opposing traffic
Provide stopping areas during emergencies
Support left-turning or U-turning vehicles
Provide refuge for pedestrians
Reducing the effect of headlight glare
Provide temporary lanes and cross-overs during maintenance operations
Medians can greatly improve the safety of the roadway. Medians can be either raised,
flushed, or depressed depending on the required functions (9, 542). A flushed median would
be utilized to facilitate the operation of reversible lanes. A raised median surrounded by a
curb should be utilized in the access control zone for the central identification island. The
minimum recommended median width is 3.6 meters (12 ft.). Automated access control systems
may be installed in the median similar to a channelization island. Therefore medians should
have infrastructure to support this potential (see Section 4.6 for additional detail).
4.2.4.3
Lane Width
The minimum lane width will be 3.0 meters (10 feet). Caution when using the minimum lane
width is warranted where large vehicle traffic is anticipated, as a 3-meter lane is highly
restrictive. The narrow lane would also negatively impact the ability to conduct safe POV
inspections that are required during periods of higher FPCON or during the exercise of RAMs.
The designer should also assess the impact of a narrow lane on the capacity of the ECF.
Traffic flow is restricted when the lane width is less than 3.6 meters (12 feet) due to the close
proximity of vehicles, which leads to motorists compensating by driving more cautiously and
increasing the spacing between vehicles (9, 247). The preferred lane width, facilitating the
flow of traffic and other operations, is 3.6 meters (12 feet).
For lanes or pull-off areas utilized for random inspection purposes, the minimum width will be
5.5 meters (18 ft.) to facilitate the safe inspection of vehicles. The length of the pull-off area
will be a minimum of 12.2 meters (40 ft.) or the length required to support the largest
expected vehicle at the ECF.
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