lecture-8 final - airport

5/25/2018 Lecture-8 Final - Airport

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CE-363

Lecture 7: Taxiway

Dr. Ankit Gupta,Assistant Professor

Department of Civil Engineering

National Institute of Technology Hamirpur


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Lecture Outline

Taxiway Requirements

Length, Width of Taxiway

Transverse and Longitudinal Grade Sight Distance

Design of Turning Radius


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Taxiway

Taxiways are defined as paths on the airfieldsurface for the taxing of aircraft and are intendedto provide linkage between one part of theairfield and another

Aircraft movement on taxiways are essentiallyground movements and are relatively slow


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Taxiway

Types

Apron taxiway

Located on the periphery of an apron to provide

uninterrupted taxing of aircraft across the apron

Dual parallel taxiway

Two parallel taxiways on which aircraft can taxi in

opposite directions Terminal taxilane

It is a portion of an apron intended to provide

access to only aircraft stands or gate positions


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Taxiway

Factors controlling layout

Minimum interference between just landed aircraft

and ready to take-off aircraft

Provision of separate entrance and exit taxiway atvarious locations along the runway to clear the

runway as soon as possible or provision of

parallel one-way taxiways

Avoiding intersection of taxiway and active runway


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Taxiway

Factors controlling layout

Facilitating higher turn-off speeds, for reducing

runway occupancy and increasing airport capacity

Shortest possible distance between terminalbuilding and end of take-off runway


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TaxiwayGeometric

Length

Longitudinal gradient

Rate of change of longitudinal gradient

Width of taxiway

Sight distance

Transverse gradient

Width of safety area Turning Radius


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TaxiwayGeometric


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TaxiwayGeometric


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TaxiwayGeometric

Length

As short as possible

It will increase as number of taxiways have to be

provided along the runway


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TaxiwayGeometric

Longitudinal gradient

Level taxiways are operationally more desirable

If gradient is steep it affects fuel consumption

As per ICAO, maximum longitudinal gradient is

3% for A and B type of airports and 1.5% for C, D

and E type of airport


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TaxiwayGeometric


Available sight distance on the pavement is

affected by the rate of change of longitudinal

gradient. As per ICAO, the maximum change in pavement

longitudinal gradient is 4% for A and B category of

airports and 3.33% for C, D and E category of

airports


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TaxiwayGeometric


This change of grade should be smooth enough

not to cause any problem to aircraft movement

Therefore, vertical curves of 30m length areprovided at such junctions


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TaxiwayGeometric


For airports with code letters A and B, ICAO

recommended length of vertical curve as 25 m for

each 1% grade change For airports with code letters C, D and E, ICAO

recommended length of vertical curve as 30 m for

each 1% grade change


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TaxiwayGeometric


FAA recommended distance between points of

grade change as:

30 |(A + B)| m

where, A and B are the percent grade changes at

the two points of grade changes along the

centreline of taxiway


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TaxiwayGeometric

Width of taxiway

Width of taxiway is lesser than runway, as aircraft

is not airborne and speeds are small.

There is not much variability in themaneuverability of aircraft and nose of aircraft

follows the taxiway centreline

Varies between 22.5 m and 7.5 m


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TaxiwayGeometric

Width of taxiway (ICAO)

Airport Code Taxiway width

A 7.5 m

B 10.5 m

C 15 m {18 m if the taxiway is used by

aircraft with a wheelbase equal to or

greater than 18 m}

D 18 m {23 m if used by aircraft with anouter main gear wheel span equal to or

greater than 9 m}

E 23 m


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TaxiwayGeometric

Sight distance

As speed of aircraft on taxiway is lower than the

speed on runway, the smaller value of sight

distance will be sufficient on the taxiway ICAO recommended that the surface of taxiway

must be visible at least up to a distance of X from

any point at a height of Y above the taxiway

surface.


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TaxiwayGeometric

Sight distance

Airport code Y X

A 1.5 m 150 mB 2 m 200 m

C,D and E 3 m 300 m


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TaxiwayGeometric

Transverse gradient

Adopted same as recommended for runways

ICAO recommended maximum pavement

transverse gradients of 2% for A and B and 1.5%for airports with code C, D and E type of airport.


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TaxiwayGeometric

Transverse gradient

FAA specify

transverse gradient of at least 3 percent for turf of

shoulders. A 4 cm drop from the paved surface to the graded

shoulder surface

Min gradient is taken as 0.5% for rigid pavement

case and 1% for other cases.


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TaxiwayGeometric

Transverse gradient (ICAO)

Strip Aerrodrum Code

Maximum transverse A B C D E

Graded portion

Upward 3.0 3.0 2.5 2.5 2.5

Downward 5.0 5.0 5.0 5.0 5.0

Un-graded portionUpward 5.0 5.0 5.0 5.0 5.0


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TaxiwayGeometric

Width of safety area

Safety area is made up of partially paved

shoulders on either side plus the area which is

graded and drained In case of jet aircraft, a paved surface of light

strength material on either side of taxiway edge

with min width of 7.5 m on both sides of pavement

edge is provided.


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TaxiwayGeometric


The pavement thickness should be

Thick enough to support the airport petrol vehicles,

etc. Surface should be treated with bitumen

It should not disintegrate due to hot blast of jet

aircraft

The surface should be smooth and impervious


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TaxiwayGeometric


As per ICAO

Aerodrum code

A B C D EPavement and shoulders - - 25m 38m 44m

Edge safety margin 1.5m 2.25m 3*m 4.5m 4.5m

Graded portion of strip 22m 25m 25m 38m 44m

* 4.5m if intended to be used by an airplane with a wheelbase equal to or greater than 18m


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TaxiwayGeometric


As per FAA

Airplane Design Group

I II III IV V VIWidth of safety 15m 24m 36m 52m 59m 79m

area

Edge safety 1.5m 2.5m 3m 4.5m 4.5m 6m

marginShoulder width 3m 3m 6m 7.5m 10.5m 12m


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TaxiwayGeometric

Turning Radius

Change in aircraft path is done by providing a

horizontal curve

The design should be such that the aircraft cannegotiate the curve without significantly reducing

the speed

Recommended radii corresponding to taxing

speeds of small, subsonic and supersonic

airplanes is 60 m, 135 m and 240 m, respectively.


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TaxiwayGeometric

Turning Radius

Relationship between exit speed and radius of

curve

Radius = V2/125f (m)

where, V is in km ph and f is coefficient of friction and is

equal to 0.13


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TaxiwayGeometric

Turning

Radius


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TaxiwayGeometric

Turning

Radius


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TaxiwayGeometric

Turning

Radius


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TaxiwayGeometric

Turning

Radius


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TaxiwayGeometric

Turning Radius

According to Horonjeff for supersonic aircraft

The radius of curve should be such that a minimum

distance of 6 m is maintained between the nearbymain gear and the edge of pavement.

R = 0.388W2/(0.5TS),


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TaxiwayGeometric

Turning Radius

According to Horonjeff for supersonic aircraft

R = radius of center line of taxiway in meters

W = wheel base of aircraft in meters

T = Width of taxiway pavement in meters

S = distance between point midway of the main

gear and the edge of taxiway pavement inmeters

S = 6 + (Wheel tread/2)


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TaxiwayGeometric

Fillets

This is the extra wide area provided at the curves

and traffic lane intersections so that rear wheel

does not go off the pavement edge Minimum radii of fillet is dependent on

The angle of intersection of traffic lanes

The wheel base of turning aircraft


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TaxiwayGeometric

Fillets

The radius is not specified for wheel base greater

than 20 m

To be determined graphically using the path of nosegear.


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TaxiwayGeometric

Fillets

Angle of Radii of fillet (in meters)

Intersection Small airport Large airport

0450

7.50 22.50450- 1350 15.00 30.00

> 1350 60.00 60.00

The radii of fillet should not be less than the width of

taxiway


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TaxiwayGeometric

Fillets For Small Airports


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TaxiwayGeometric

Fillets For Large Airports


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TaxiwayGeometric

Separation Clearance

Depends up on navigational aids, type of airport

and wing span

As per FAA, the separation clearance based onwing span (W, m) is

Taxiway centre line to 1.25W + 2.1 m

taxiway center line

Taxiway centre line to obstacle 0.75W + 2.1 m

Apron taxiway centre line 0.63W + 2.1 m

to obstacle


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TaxiwayGeometric


As per FAA, in meters

Design item Airplane Design Group

I II III IV V VI

Taxiway centre line to:

Parallel taxiway c/l 21 31 46 68 75 102

Fixed or moveable 13.5 20 28 41 46 61.5

object & to property line


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TaxiwayGeometric


As per FAA, in meters

Design item Airplane Design Group

I II III IV V VI


Fixed or 12 16 25 36 39 51

immovable object

Runway centre line 120 120 120 120 vary 180

with airport elevation


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TaxiwayGeometric


As per ICAO, in meters

Minimum Separation Aerodrome Code

A B C D E

Edge safety margin 1.5 2.25 3* 4.5 4.5


taxiway centre line 21 31.5 46.5 68.5 81.5

object 13.5 19.5 28.5 42.5 49

Aircraft stand taxilane 12 16.5 24.5 36 42.5

to object


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TaxiwayGeometric


As per ICAO, in meters

Minimum Separation Aerodrome Code

A B C D E

Min wing tip clearance 3 3 4.5 7.5 7.5

Stand safety margin 1.5 1.5 2 2.5 2.5

* 4.5 m if intended to be used by the airplane with a wheel

base equal to or greater than 18 m


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TaxiwayGeometric


Minimum separation between parallel taxiway

centreline or taxilane centreline is given by

STT= W + 2 U1+C1

Required separation between a taxiway centreline or

an apron taxiway and a fixed or moveable object

STO= 0.5W + U1+ C2


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TaxiwayGeometric


Required separation between a aircraft stand taxilane

and fixed or moveable object

SATO= 0.5W + U2+ C1


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TaxiwayGeometric


W = wing span of most demanding aircraft

U1= Taxiway edge safety margin

C1= Minimum wing tip clearance

C2= Required clearance between wing tip and

object

U2= Aircraft stand safety margin

lecture-8 final - airport

Documents

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slow5252018 lecture

junctions5252018 lecture

taxiway taxiways

maximum longitudinal

active runway5252018

taxiway types apron

taxiway factors