lecture-7 final - airport

CE-363

Lecture 7: Runway Geometric

Dr. Ankit Gupta, Assistant Professor

Department of Civil Engineering

National Institute of Technology Hamirpur

Lecture Outline

Runway Geometric

Runway Width

Transverse Grade

Longitudinal Grade

Rate of change of Longitudinal Grade

Sight Distance Requirements

Runway Geometric

Length of runway

Width of runway strip

Sight Distance

Longitudinal and Effective Gradient

Rate of Change of Longitudinal Gradient

Transverse Gradient

Safety Area

Runway Geometric

Runway Length:

Basic runway length depends up on the category

in which the aircraft falls as per ICAO

classification

This length is modified for elevation, temperature

and gradient correction

Runway Geometric

Airport Reference Code

This is a coding system used to relate the airport

design criteria to the operational and physical

characteristics of the aircraft intended to operate

at the airport.

This is based up on the aircraft approach category

and the airplane design group

Runway Geometric


Airplane design group is a grouping of aircraft

based up on wingspan.

Aircraft approach category is determined by the

aircraft approach speed, which is defined as 1.33

times the stall speed in the landing configuration

of aircraft at the maximum certified landing weight

Runway Geometric


Aircraft Aircraft Airplane design Aircraft

approach approach Group wingspan,m

category speed, kn

A < 91 I < 14.85

B 91 - 121 II 14.85 -23.93

C 121 - 141 III 23.93 -35.75

D 141 -166 IV 35.75 -51.81

E > = 166 V 51.81 -64.85

VI 64.85 -79.39

Runway Geometric

Runway length requirements for various aircraft

Aircraft Runway length, m

Small airplanes with < 10 passenger seats

75% of fleet 750

95% of fleet 920

100% of fleet 1090

Small airplanes with 10 or more 1270

passenger seats

Runway Geometric



Large airplanes of 60000 lb or less

75% of fleet at 60% useful load 1615




Runway Geometric



Large airplanes of more than 60000 lb

stage length of 1600 km 1815




Runway Geometric

Runway Width:

Depends upon the type of airport and largest

aircraft in operation

In case of large aircraft, the central 30m width of

the runway pavement is observed to take more

concentrated air-traffic load

Also, it requires additional space on the two sides

of this 30 m width so as to protect the possible

damage to the farthest machinery i.e. engines

from ingestion of loose material of shoulders

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

Runway Geometric

Runway Width:

In case of code number 1 and 2, if precision runway is used then width should not be less than 30 m.

Width of 45m is sufficient for large airports.

Runway Geometric

Sight Distance

Generally no sight distance restrictions as the

longitudinal gradients for the runway are quite gentle.

Hazardous locations are crossings of two runways or

runway and taxiway

Adherence to runway longitudinal gradient standards

provides adequate line of sight

Runway Geometric

Sight Distance

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 Geometric

Sight Distance

Runway grade should be such that any two points

Y meters above runway centreline will be mutually

visible for a minimum distance of X

Runway Geometric

Runway Gradient

Longitudinal and Effective gradient

The longitudinal gradient of runway increases the

required runway length

It also affects the aircraft performance

These should be as flat as possible to avoid

excessive engine thrust

ICAO limits the maximum longitudinal gradient to

1.25 to 1.5 percent for runways that serve the

largest type of aircraft

Runway Geometric

Runway Gradient

Rate of change of Effective longitudinal

gradient

The abrupt grade change may cause premature lift

off of aircraft during take off

The change in gradient should be smooth through

the provision of vertical curves

No vertical curve is required if the grade change is

less than 0.4 percent

Runway Geometric

Runway Gradient

Rate of change of Effective longitudinal

gradient

Type of airport Max Long. Grad. Max. Eff. Grad.

A, B, C 1.50% 1.00%

D, E 2.00% 2.00%

Runway Geometric

Runway Gradient

Rate of change of Effective longitudinal gradient

Type of Rate of change/Distance between

airport 30m length of curve grade intersection

A, B 0.10% < 300(a+b)m

C 0.20% < 150(a+b)m

D, E 0.40% < 50(a+b)m

‘a’ and ‘b’ are angle of interchange between grades

Runway Geometric


a

b

y x z

D

L1 L2

Runway Geometric


Small airport Large airport

Maximum ‘a’ or ‘b’ 2% 1.5%

L1 or L2/1% grade change 90m 300m

D 75(a+b)m 300(a+b)m

Runway Geometric


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 change

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

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

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

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

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 rigid pavement it may be kept as low as 0.5%

Runway Geometric

Transverse Gradient

Slope upto 2% are permitted for runways that

serve smaller classes of aircraft (Code A and B).

For other runways, maximum transverse slope is

1.5%

For shoulders, slope of upto 5% is permitted

FAA recommends a 4 cm drop from the paved

runway surface to the graded shoulder surface

Runway Geometric

Transverse Gradient

45m

150m

300m

1 - 2% 3 - 5%

1.5 - 5%

1 - 2% 3 - 5%

1.5 - 5%

Runway Shoulder Shoulder

Runway Safety Area

Runway Geometric

Transverse Gradient

Runway Geometric

Safety Area

The runway safety area is an area which is

cleared, drained and graded. It includes the

structural pavement, shoulders on either side of

runway and the additional width.

Runway Geometric

Safety Area

Structural Pavement

Shoulder

Shoulder

60m 60m

Extended Runway

Safety Area

Extended Runway

Safety Area

300 m

Runway safety

Area

Runway Geometric

Safety Area

ICAO recommendations

Code Number Code Number

1 2 3 4

Width of runway strip

Precision approach 150 150 300 300

Non-precision instrument 150 150 300 300

approach

Visual approach 60 80 150 150

Runway Geometric

Safety Area

ICAO recommendations

Code Number Code Number

1 2 3 4

Width of cleared and graded area

Instrumental approach 80 80 150 150

Visual approach 60 80 150 150

Runway Geometric

Shoulders

These are usually lesser strength pavements and

are provided on both sides of the runway strip

They impart a sense of openness to the pilots

Sometimes these are stablised to resist jet blast

erosion or to accommodate maintenance

equipment

Shoulders for small airports may be turfed

Runway Geometric

Shoulders

Shoulders are useful during emergency landing or

take-off

These are not meant for regular application of

load

Runway Geometric

Blast pad

Runway blast pads may be constructed at the

ends of the runway that serve jet operations

the blast pad extends across the full width of the

runway and its both side shoulders

this is essentially non-traffic area

Blast pads vary in length from 30 m to 120 m

depending up on the type of aircraft to be served

Parallel Runway System Spacing

Depends up on

Whether operation is in Visual Meteorological

condition (VMC) or in Instrument Meteorological

condition (IMC)

In case of IMC, whether it is desired to

accommodate simultaneous arrivals or

simultaneous arrivals and departures

In case of airports, serving both heavy and light

aircraft, simultaneous use of runways even in

VMC conditions may be dictated by separation

requirements to safeguard against wake vortices


Recommendations

Under VMC, disregarding wake vortices

FAA recommends parallel runway centreline

separation of

90 m for single engine propeller aircraft

150 m for twin engine propeller aircraft

210 m for all other aircraft

Also, separation may be increased to 360 m for

airplane design groups V and VI


Recommendations


ICAO recommends minimum separation of parallel

runway centreline as

120 m for airport reference code 1

150 m for airport reference code 2

210 m for airport reference code 3 and 4


Recommendations


FAA recommends parallel runway centreline

separation of

420 m during day-light hours for opposite direction

operations and 840 m at all other times

Under VMC, considering wake vortices

FAA recommends minimum separation of 750 m


Recommendations

Under IMC, for simultaneous instrument

approaches

ICAO recommends minimum separation of parallel

runway centreline as 1525 m and FAA

recommends 1290 m.

For instrumental approaches. Both the FAA and

ICAO recommended centreline separation of 915 m


FAA Recommendations

Simultaneous VFR operations

All aircraft 210 m

Simultaneous IFR operations

Segregated operations 760 m

Radar departures 760 m

Nonradar departures 1000 m

Dependent arrivals 915 m

Independent arrivals 1300 m


ICAO Recommendations

Simultaneous VFR operations

Aerodrum code 1 120 m

Aerodrum code 2 150 m

Aerodrum code 3 and 4 210 m


ICAO Recommendations

Simultaneous IFR operations

Segregated operations 760 m

Independent departures 760 m

Dependent arrivals 915 m

Independent arrivals 1525 m

lecture-7 final - airport

Documents