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AIM

10/12/17

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
(for example, 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
FIG 2

−3−6.

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,
as shown in FIG 2

−3−4.