Page 272 - Planning and Design of Airports

Geometric Design of the Airfield 233

7.5 m for aerodrome code letter D and E runways. The minimum
clearance between the edge of each taxiway and the outer main gear
wheels, the taxiway edge safety margin U , is given in Table 6-20. This
1
clearance provides a minimum taxiway centerline to a parallel taxi-
way centerline or taxilane centerline separation given by Eq. (6-1).

S = WS + 2U + C (6-1)
TT 1 1
where S = minimum taxiway-to-taxiway or taxiway-to-taxilane
TT
separation
WS = wingspan of the most demanding aircraft
U = taxiway edge safety margin
1
C = minimum wingtip clearance
1
Therefore, for example, an ICAO aerodrome code letter E run-
way, which accommodates aircraft with wingspans up to 65 m,
requires a taxiway centerline to a taxiway centerline or a taxilane cen-
terline separation from Eq. (6-1) of 65 + 2(4.5) + 7.5 = 81.5 m.
The required separation between a taxiway centerline or an
apron taxiway centerline and a fixed or movable object is found from
Eq. (6-2).

S = 0.5 WS + U + C (6-2)
TO 1 2
where S is the minimum taxiway or apron taxiway to a fixed or
TO
movable object separation and C is the required clearance between a
2
wingtip and an object.
The required clearance between a wingtip and an object C is 4.5 m
2
for aerodrome code letter A runways, 5.25 m for aerodrome code let-
ter B runways, 7.5 m for aerodrome code letter C runways, and 12 m
for aerodrome code letter D and E runways.
The required separation between an aircraft stand taxilane cen-
terline and a fixed or movable object is found from Eq. (6-3).

S = 0.5 WS + U + C (6-3)
ATO 2 1
where S is the minimum aircraft stand taxilane to fixed or movable
ATO
object separation and U is the aircraft stand safety margin.
2
Since aircraft moving on the aircraft stand taxilane are moving
at low speed and are often under positive ground guidance, the
aircraft stand safety margin is less than on the taxiway system.
The value for this safety margin U is 1.5 m for aerodrome code
2
letter A and B airports, 2 m for aerodrome code letter C airports,
and 2.5 m for aerodrome code letter D or E airports. The taxiway
and taxilane separation criteria adopted by ICAO are given in
Table 6-20.