ce-461 runway geometric design

7/24/2019 CE-461 Runway Geometric Design

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Transportation Engineering - II

Airport Classification&

Runway Geometric Design

Dr. Indrajit Ghosh

Assistant Professor

Department of Civil Engineering

Indian Institute of Technology Roorkee


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Lecture Outline

Airport Classification ICAO

FAA

Runway Geometric Runway length

Runway Width

Transverse Grade Longitudinal Grade

Rate of change of Longitudinal Grade

Sight Distance Requirements


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Airport Classification

In order to provide a guideline to airport

designers for a reasonable amount of

uniformity in airport landing facilities

Design criteria have been prepared by ICAO

and FAA through airport classification


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ICAO classification

Employ an aerodrome reference code

consisting of two elements

Element 1: a number based on effective runwaylength

Element 2: a letter based on aircraft wing span and

outer main gear wheel span

Code number or letter within an element

selected for design purposes is related to

critical airplane characteristics

For which facility is provided


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ICAO Reference Code

Code element 1 Code element 2

Code no. Aeroplane

reference field

length (m)

Code letter Wing span

(m)

Outer main

gear wheel

span (m)*

1


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An airport designed to accommodate a

Boeing 767-200 with an outer main gear

wheel span of 10.44 m width, a wingspan of

48 m, at a maximum take off weight of 144tonne, requiring a runway length of about

1830 m at sea level on a standard day will be

classified as _____________


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FAA Airport Reference Code

Coding system used to relate the airport design

criteria to the operational and physical

characteristics of the aircraft intended to operateat the airport

Based up on

Aircraft approach category

Approach speed

Airplane design group to which the aircraft is assigned

Based on wingspan and tail height


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FAA Reference Code

Aircraft approach

category

Aircraft approach

speed (kn)

Airport category

A


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FAA airport approach category classification

Two broad airport classes

Utility airports

Designed, constructed and maintained to

accommodate aircraft from approach categories A & B

Serve small aircraft with maximum take-off weight of

12500 lbs (up to 5000 kg)

Transport airports

Can accommodate large aircraft with maximum take off

weight in excess of 12500 lbs (above 5000 kg)


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FAA Reference Code

FAA Airplane Design Groups for Geometric Design of Airports

Airplane design

groups

Aircraft wingspan (m) Tail height (m)

I < 14.9


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Runway Geometric

ICAO gives various geometric standards for

airport design

Most of its member provide international air

service

To have uniformity in landing facility at

airports located in different countries

Desirable to follow common design standardsas recommended by ICAO


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Runway Geometric

Following items are considered

Runway length

Runway width

Width and length of safety area

Transverse gradient

Longitudinal and effective gradient Rate of change of longitudinal gradient

Sight distance


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Runway Geometric

Runway Length

One of the most significant factor in deciding size

and cost of airport

Length should be sufficient for take off andlanding of CRITICAL AIRCRAFT DESIRING

SERVICE AT AIRPORT

Basic runway length

Modified for elevation, temperature and gradient

correction

Airports are classified according to reference

codes (ICAO) based on aeroplane reference field

lengths


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Runway Geometric

Runway Width

Depends upon type of airport and largest aircraft

in operation

Studies have shown aircraft traffic is moreconcentrated in central part of runway

Lateral distribution of traffic on runway can be

represented by a normal distribution

% wheel load applications vs. distance from centerline ofrunway

Impact of factors like night operation, crosswind,

wet pavements is not significant on distribution of

aircraft traffic on runway


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Runway Geometric

Runway Width

In case of large airport serving large aircrafts, the

central 30 m width of the runway pavement is

observed to take more concentrated air traffic load It requires additional space of 15 m so as to keep

outermost part of jet engine aircrafts on paved

surface

To protect the possible damage to the farthest

machinery

Engine damage from ingestion of loose material of

shoulders


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Runway Geometric

Runway Width

As per ICAO (in meters)

Code Letter

Code Number A B C D E

1 18 18 23 - -

2 23 23 30 - -

3 30 30 30 45 -

4 - - 45 45 45


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Runway Geometric

Runway Width

In case of ICAO code number 1 and 2, if precisionapproach runway is used then width should not be

less than 30 m. Width of 45 m is sufficient for large airports.


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Runway Geometric

Safety Area Landing strip

Paved area + shoulder

Shoulders Useful during emergency landing or take-off

Not meant for regular application of load

Are usually of lesser strength pavements and are

provided on both sides of the runway strip Impart physiological improvement

Openness to the pilots


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Runway Geometric

Shoulders

Sometimes stablised

To resist jet blast erosion

To accommodate maintenance/emergency equipment Shoulders for small airports may be turfed

Safety area

Width of safety area as per ICAO Non-instrumental runway 75 m (min.)

Instrumental runway 150 m (min.)


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Runway Geometric

Blast pad

Area constructed at the ends of the runway that

serve jet operations

To prevent erosion of surfaces adjacent to runway ends

Extends across full width of runway and its both

side shoulders

Essentially non-traffic area

Varies in length from 30 m to 120 m

Depends up on type of aircraft to be served


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Runway Geometric

Runway Gradient Longitudinal grade and grade change

Level runway is ideal for safe aircraft operations

Cost of excessive earthwork precludes its design Longitudinal gradients should be as flat as possible

To avoid excessive engine thrust

Should not restrict sight distance


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Runway Geometric

Runway Gradient

Longitudinal grade and grade change

Changes in longitudinal gradient should be smooth

Through provision of vertical curves

Abrupt grade change

Cause premature lift off of aircrafts during take-off

Grade changes should not be very frequent

Restrict sight distance and increase runway length


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Runway Geometric

Runway Gradient

Longitudinal grade and grade change

ICAO limits the maximum longitudinal gradient of

1.25 to 1.5 percent for runways that serve the

largest type of aircraft (Code 3 & 4) 2 percent for small aircrafts (Code 1 & 2)

Flatter grades should be provided in first and last

quarters of runways

0 to 0.8 percent


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Runway Geometric

Runway Gradient Longitudinal grade and grade change

ICAO has specified minimum distance between

points of grade intersections of two successivegrade changes

Based on sum of absolute values of corresponding

grade changes

No vertical curve is required when grade change isless than 0.4 percent


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Runway Geometric

Rate of Change of Longitudinal Gradient

a

b

yxz

D

L1L2


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Runway Geometric

Rate of Change of Longitudinal Gradient

Grade Design Criteria (ICAO)

ICAO Max Max grade Max. Max. Distance Length

code Long. First & last Effec. Grade Bet. Points of

No Grade quarter Grade Change of grade vertical

% grade % % intersection(m) curve (m)

4 1.25 0.8 1.0 1.5 300 (A+B) 300 A or B

3 1.5 0.8 1.0 1.5 150 (A+B) 150 A or B

2 2.0 - 1.0 2.0 50 (A+B) 75 A or B

1 2.0 - 2.0 2.0 50 (A+B) 75 A or B


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Runway Geometric

Transverse Gradient

Provided for quick disposal of surface water

Ponding of water is hazardous for aircraft operation

Minimum recommended transverse slope is 1

percent for flexible pavement

For rigid pavement it may be kept as low as 0.5 percent


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Runway Geometric

Transverse Gradient

Slope up to 2 percent are permitted for runways

that serve smaller aircrafts (ICAO Reference

Code A and B) For others, maximum is 1.5 percent

Shoulders require steeper slopes

Slope of up to 5 percent is permitted for first 3 m

beyond pavement edge

1.5 3 percent thereafter

FAA recommends a 4 cm drop from the paved

runway surface to the graded shoulder surface


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Runway Geometric

Transverse Gradient


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Runway Geometric

Sight Distance

Should be as unrestrictive as possible

Generally no sight distance restrictions as the

longitudinal gradients for the runway are quite gentle Adherence to runway longitudinal gradient standards provides

adequate line of sight

Hazardous locations are crossings of two runways or

runway and taxiway


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Runway Geometric

Sight Distance (ICAO recommendation)

Airport category Y (meter) X

ICAO code letter A 1.5 half runway length

ICAO code letter B 2.1 Half runway length

ICAO code letter C, 3.0 Half runway length

D, E

Runway grade should be such that any two points Y

meters above runway centerline will be mutually visible

for a minimum distance of X

ce-461 runway geometric design

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