design of air side area

8/3/2019 Design of Air Side Area

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Design of Air Side Area

Airside facilities exist primarily for aircraft take-off and landing operations. The most

important physical element is the runway. Taxiways, holding pad, and apron gate are

all developed in association with runways to permit the aircraft to move efficiently

while on the ground.

As air traffic demand for airside facilities grows, an immediate remedy may be to

increase airport capacity by an expansion of the existing airside facilities. The

decision would imply modifying the present runway and taxiway configuration in a

manner, which would increase airport capacity; the FAA has published numerous

guides to aid airport planners in determining the best upgrading procedures for air

side facilities.

1 Runway Configuration1.1. TYPES

There are four basic runway configurations:

1. Single runways,2. Parallel runways,3. Intersecting runways, and4. Open-V runways,Many airports around the world combine aspects of these basic configurations.

1. SINGLE RUNWAY The simplest configuration is the. Only one landing or take-off can occur at any one time, therefore, the

capacity of such a runway is very limited.

2.PARALLEL RUNWAYS

Many times, if a single runway will not suffice, a second parallelrunway may be added,

usually a "close," "intermediate," or "far" parallel runway. Close parallel runways are spaced at a minimum of 700 ft (213.36 m)

and can be as wide apart as 3,500 ft (1,066.80 m).

A spacing of 700 ft is possible only under VFR conditions, and onerunway is used for landings and the other for take-offs

If IFRs prevail, the spacing must be a minimum of 3,500 ft (1,066.80m) for one runway to be used for arrivals and the others for departures


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simultaneously.

If the runways are staggered, the separation can be increased ordecreased by 100 ft (30.48 m) for every 500 ft (152.40 m) of

stagger/Intermediate parallel runways are those spaced between 3,500

and 5,000 ft (1,066.80 m and 1,542.00 m) apart.

Under IFR conditions this type is considered independent if onerunway is used for take-offs and the other for landings.

Far parallel runways are spaced over 4,300 (1310.64 m) apart. Underany conditions this spacing allows runways to be used simultaneously

for both arrivals and departures.

As airport travel demand increases, it may be desirable to add moreparallel runways. Some airports have as many as four parallel

runways.

3.INTERSECTING RUNWAYS

Are used when there is a likelihood of strong winds in more thanone direction.

Under windy conditions only one of these runways can be used, butif winds are light, both runways can be used simultaneously.

4.OPEN-V RUNWAYS

Are runways that do not intersect and are not parallel to each other. These runways are subject to the same restrictions as for intersecting

runways in windy conditions.

1.2.Factors

The configuration of runways used and their orientation depends on many factors,

including

Wind, Neighboring airports and airways, Obstructions, Topography, Restricted areas, Bird hazards,


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Control tower visibility, Jet blast and wing tip vortices, Runway length, and Environmental factors.All of these factors are briefly described below

Wind

Orientation of a runway depends greatly on wind direction. The most desirable orientation avoids crosswinds all together. The FAA

specifies that runways should be oriented so that 95% of the time landing of

aircraft is possible with crosswind components not exceeding 15 mph(24.14 kmph).

Large air carrier aircraft can land with crosswinds greater than this, butsince most airports also allow smaller aircraft to land on the same runway,

this specification should prevail wherever possible.

If this wind standard cannot be met, the normal practice is to constructintersecting runways in the direction of heavy winds.

A single runway will suffice only if winds come predominantly from onedirection.)

WIND ROSE

A goodway to determine the best orientation of a runway with regard towind is with the aid of a wind rose,

To be able to use a wind rose, wind data for a ten-year period describingwind directions and speeds must first be collected .'

the wind directions are split into 36 categories, each covering a 10 span. The wind speed and direction data are converted into percentages of the

total observations and entered into the appropriate segment of the wind

rose.

The wind categories are denoted by the radial lines, and wind speedcategories are shown by the concentric circles, the slowest speed being in

the center.


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Obstructions

To avoid future problems from obstructions, land adjacent to the airportshould be zoned to allow only development below the obstruction level

heights.

Obstructions are determined to exist if they fall above levels of certainimaginary surfaces defined by the FAA. The imaginary surfaces are defined in

the following manner:

1. Primary Surface. A surface longitudinally centered on a runway. When the runway

is paved, the primary surface extends 200 ft (60.96 m) beyond each end of the

runway.

2.Horizontal Surface. A horizontal plane 150 ft (45.72 m) above the established

airport elevation, the perimeter of which is constructed by swinging arcs of

specified radii from the center of each end of the primary surface of each runway

and connecting the adjacent arcs of lines tangent to those arcs.

3. Conical Surface. A surface extending outward and upward from the periphery of

the horizontal surface at a slope of 20 to 1 for a horizontal distance of 4,000 ft

(1219.20m).

4.Approach Surface. A surface longitudinally centered on the extended runway

centerline and extending outward and upward from each end of the primary

surface.

5. Transitional Surfaces. Surfaces that extend outward and upward at right angles to

the runway centerline plus the runway centerline extended at a slope of 7 to 1 from

the sides of the primary surface and approach surfaces.

The ICAO establishes the international regulations which are generally similar.

Runway Geometry

The runway is made up of various components. These components are shown in Fig.

and are described as follows:

1. Structural Pavement. This is the part of the runway where the planes actually

take off and land. The runway is normally used in both directions so that it is

actually two separate runways. The runway pavement is most typically 150 ft

(45.72 m) wide. However, some 200-ft (60.96-m) runways are now being

designed to facilitate the modern larger aircraft.


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2. Shoulder. The shoulder is most typically a stabilized strip of earth adjacent to

both sides of the runway pavement. The width varies anywhere from 25 to 50 ft

(7.62 to 15.24 m), depending on the size of the airport. Most larger airports have

about 50 ft (15.24 m) of shoulder on either side. The purpose of the shoulder is to

accommodate maintenance and emergency vehicles. Also, the shoulder area is

built to resist jet blast erosion.

3.Blast Pad, The blast pad serves basically the same purpose as the shoulder, but

is located at the end of the runway. The blast pad is built as wide as the shoulder

extends and is usually at least 200 ft (60.96 m) long.

4. Safety Area. The safety area contains the pavement, shoulders, blast pad, and an

area on the side of the shoulder which is cleared, drained, and graded. The side

area is usually turfed. It should be designed for an occasional aircraft to pass over

without any major damage. Maintenance and emergency vehicles should be able to

drive over this area also. The safety area should be at least 500 ft (152.40m) wide.

5.Extended Safety Area. .Occasionally, an aircraft will overshoot or under run the

runway. Most of the time this type of accident will occur within 1,000 ft (304.8 m)

of the end of the runway. For this reason it is recommended that runways have an

extended safety area. As in the safety areas, this area must be cleared, drained, and

graded. It should be able to support an occasional airplane and emergency and

maintenance vehicles. This area starts at the end of the blasting pad and extends

about 800 ft (243.86 m) beyond the pad. The extended safety area is built to be as

wide as the safety area.


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Taxiway Layout

Taxiways should be arranged to result in the shortest practicabledistances from the terminal area to the ends of runways used for take-

off.

at busy airports they should be located at various strategic points alongrunways, so that landing aircraft can leave the runways as quickly as

possible to clear them for use by other aircraft.

Whenever possible, taxiways should be routed so as to avoid crossingof active runways. There are three basic types of taxiways:

a)entrance,

b) exit, andc) bypass taxiways.

A )Entrance Taxiway.

The entrance taxiway is used for entering the runway from the terminal. It can be designed so that delay can be decreased by allowing aircraft to

accelerate while entering the runway.

Higher speeds can be attained if turning radius is increased. Speeds as high as 60 mph (96.56 kph) can be safely reached if the

curve radius is 1,800 ft (548.64 m).

An important consideration for a highspeed entrance taxiway isavailable land.. An entrance taxiway allowing 60-mph (96.56-kph)

speeds needs about 3,200 ft (975.36 m) more space between taxiway

and runway than a 20-mph (32.19-kph) speed allowance.

B)Exit Taxiway.

It is desirable, especially at busy airports, to have aircraft vacatethe runway as quickly as possible.

There are two basic types of exits: the right angle exit and thehigh-speed exit.

The right angle exit, shown in Fig. 20.9 is used mainly at low-traffic airports to save on construction costs.

At smaller airports this type of exit will be found at each end of therunway and at the center. However, this is not the most efficient


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method of getting aircraft off the runway.

The high-speed exit, which is generally built at a 30 angle to therunway, is considered to be much more efficient.

Speeds up to 65 mph (104.60 kph) can be safely maintainedwithout any adverse effects on passenger comfort.

It is normally desirable to have an exit that starts with a largeradius curve and then goes to a smaller radius.

The transition radius is provided to reduce excessive tire wear onthe aircraft.

C)Bypass Taxiways

. Bypass taxiways are sometimes constructed at busy airports,that is, where there are at least 20 total operations per normal

peak hour or 50,000 air carrier operations annually.

The purposes of bypass taxiways is to allow aircraft ready fortake-off to bypass preceding aircraft that are not yet ready to

take off and are blocking the entrance taxiway.

These bypass taxiways are located near, and are similar indesign to, the entrance taxiway

1.5. Holding Aprons

Holding aprons are located at or near the runway entrance. The apron is constructed to allow aircraft to make a final check before

take-off and to allow planes to bypass any other aircraft not ready to

take off. This helps to reduce delays.

Aprons are usually built large enough so that about four aircraft can belocated there at one time.

To determine the amount of space needed for each aircraft, multiply thewingspan by a factor from 1.35 to 1.60 for aircraft with dual wheel

undercarriages and by a factor from 1.60 to 1.75 for aircraft with dual

tandem landing gears.


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Markings

Runway Marking. Runway markings are important for the safety ofaircraft, primarily during daylight hours, when these markings can most

readily be seen.

Markings are also helpful during times of poor visibility to createregularity and efficiency in airport operations. Runway markings can

be classified as follows:

1.Basic Runway Marking. This includes markings needed for runways where

only direct visual identification is made from the aircraft.

2.Non precision Instrument Runway Marking. This includes markings needed

for straight-in landings for which only the aid of the signals from a very

high-frequency omnirange station (VOR) are used to guide the aircraft.

3. Precision Instrument Runway Marking. Runways that are equipped with

electronic aids such as the instrument landing system (ILS).

When two runways intersect, the higher-ranking runway markings will be

used. For example, a precision runway would have precedence over a non

precision runway, and a non precision runway would rank higher than a basic

runway.

Basic Runway Marking

all runway markings are normally white to differentiate them from yellowtaxiways and apron markings.

The basic runway markings include centerline strips, threshold markers,and runway designation number and letters.

Numbers and letters are approximately 20 ft (6.10 m) wide and 60 ft(18.29 m) tall.

The runway is marked by the whole number nearest to one tenth of themagnetic azimuth of the runway centerline measured clockwise from

magnetic north.

For example, a runway centerline bearing of North 160 East would benumbered 16 on the south end and 32 on the north end.


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Letters are added if there are two or more parallel runways. For example, ifthree runways are parallel, they would be lettered L (left), C (center), R

(right), from left to right.

Non precision Instrument Runway Marking

A nonprecision instrument runway uses the same marking as abasic runway, but elements of the precision instrument runway

may be added.

The precision instrument runway provides the basic runwaymarkings plus touchdown zone markers and side stripes.

Taxiway Marking,

The centerlines of taxiways are marked with a solid yellow line thatis at least 6 in. (15.24 cm) wide.

At intersections with runways, the stripe is continued until it meetsthe centerline of the runway, except at the end of the runway, where

this line terminates at the runway edge.

When two taxiways intersect, the lines are continuous. When the edge of the taxiway pavement is not easily identifiable, it

is also necessary to provide edge markings. This consists of two

parallel yellow lines, each 6 in. (15.24 cm) wide, separated by a 6-

in. (15.24 cm) space.

Where taxiways enter the runway, it is also necessary to provide ataxiway holding line. At large airports this line is 150 ft (45.72 m)

from the edge of the taxiway.

Taxiway Guidance Signing

Signs are placed along taxiways and aprons to help pilots aroundbusy airport.

These signs also aid them in complying with instructions fromground controller. There are two types of taxiways guidance signs:

1.Destination Signs. These signs indicate paths to be taken by incoming

outgoing aircraft.


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2.Intersection Signs. These designate the location of intersecting routes or

indicate category II ILS critical areas.

The following are some typical examples of taxiway guidance signs and their

meaning:

RAMP. general parking, servicing and loading areas;

MIL. area for military aircraft;

HGR. hangar area;

CRGO. freight and cargo handling area.

Today, guidance signs are made of a retroreflective material, so thatthey are easy to see and less expensive to make than the old signs

using yellow letters a black background.

The maximum height of these signs is 30 in. (76.20 cm) abovefinished grade, and they are at a minimum distance of 10 ft (3.05 m)

from apron J and taxiway edges.

design of air side area

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