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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.