UFC 4-022-01
25 May 2005
It is recommended that passive vehicle barriers defining the boundary of the ECF be
located 12 ft (3.6 m) from the edge of road. Where passive vehicle barriers must extend
close to the active vehicle barriers at the end of the response zone to maintain
containment, this minimum is not applicable.
Additionally, in the Access Control Zone, the location of facilities and access control
equipment will likely provide less lateral clearance. Where possible, maintain a
minimum lateral clearance of 2 ft (610 mm) in the access control zone to allow security
personnel to pass between the obstruction and the roadway. Maintain a minimum
lateral clearance of 3 ft (914 mm) between facilities and the roadway.
6-6.9
Vertical Clearances
AASHTO standards indicate a minimum vertical clearance of 14 ft (4.3 m) for highways
or 16 ft (4.9 m) for freeways or arterials. Provide a minimum vertical clearance of 14 ft 6
in (4.41 m) for general use and 17 ft 6 in (5.4 m) in commercial vehicle inspection areas
or where a large number of over-height vehicles are expected.
In order to support potential over-height vehicles or future pavement overlays, a
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minimum vertical clearance of 17 ft (5.2 m) should be maintained throughout the ECF.
6-6.10 Corner Radii
The radius of a corner or turning lane depends on the largest vehicle expected to use
the lane and the average turning speeds, which will be quite low around an ECF. Other
factors to consider include the available right-of-way, the angle of the intersection, and
pedestrian activity. The following minimum inside radii should be used.
Locations serving only passenger vehicles, 15 ft (4.57 m) to 30 ft (9.14 m),
preferred is20 ft (6.1 m).
Corners where RVs, SUVs, or similar vehicles turn, 35 ft (10.67 m).
Intersections where large trucks (WB-50) including semi-trailers (WB-67) turn,
50 ft (15.24 m).
Turnarounds for large trucks, 65 ft (19.81 m).
6-7
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. 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. Additional guidance on traffic considerations at Entry Control Facilities can
be found in Traffic and Safety Engineering for Better Entry Control Facilities.
6-7.1
Capacity
6-19
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