AIM
4/3/14
2−3−4
Airport Marking Aids and Signs
1. Relocation of a Threshold.
Sometimes
construction, maintenance, or other activities require
the threshold to be relocated towards the rollout end
of the runway. (See FIG 2−3−3.) When a threshold is
relocated, it closes not only a set portion of the
approach end of a runway, but also shortens the length
of the opposite direction runway. In these cases, a
NOTAM should be issued by the airport operator
identifying the portion of the runway that is closed,
e.g., 10/28 W 900 CLSD. Because the duration of the
relocation can vary from a few hours to several
months, methods identifying the new threshold may
vary. One common practice is to use a ten feet wide
white threshold bar across the width of the runway.
Although the runway lights in the area between the
old threshold and new threshold will not be
illuminated, the runway markings in this area may or
may not be obliterated, removed, or covered.
2. Displaced Threshold.
A displaced thresh-
old is a threshold located at a point on the runway
other than the designated beginning of the runway.
Displacement of a threshold reduces the length of
runway available for landings. The portion of runway
behind a displaced threshold is available for takeoffs
in either direction and landings from the opposite
direction. A ten feet wide white threshold bar is
located across the width of the runway at the
displaced threshold. White arrows are located along
the centerline in the area between the beginning of the
runway and displaced threshold. White arrow heads
are located across the width of the runway just prior
to the threshold bar, as shown in FIG 2−3−4.
NOTE
−
Airport operator. When reporting the relocation or
displacement of a threshold, the airport operator should
avoid language which confuses the two.
i. Demarcation Bar.
A demarcation bar delin-
eates a runway with a displaced threshold from a blast
pad, stopway or taxiway that precedes the runway. A
demarcation bar is 3 feet (1m) wide and yellow, since
it is not located on the runway as shown in
1. Chevrons.
These markings are used to show
pavement areas aligned with the runway that are
unusable for landing, takeoff, and taxiing. Chevrons
are yellow. (See FIG 2−3−7.)
j. Runway Threshold Bar.
A threshold bar
delineates the beginning of the runway that is
available for landing when the threshold has been
relocated or displaced. A threshold bar is 10 feet (3m)
in width and extends across the width of the runway,