Airport Engineering - Design

Airport Design:

Design Orientation

The runway is usually oriented in the direction of prevailing winds. The winds is the direction opposite to the direction of landing and take-off, provides greater lift on the wings of the aircraft when it is taking off.

The Maximum permissible cross wind component depends upon the size of the aircraft and the wing configuration.

Airport Serving and Max Limit:

1. For Small Aircraft - 15 kmph

2. For mixed traffic - 25 kmph

2. For Big Aircraft - 35 kmph

Runway Length

The length of runway under the following assumed conditions at the airport:

1. Airport altitude is at sea level

2. Temperature at the airport is standard (15 degree)

3. Runway is leveled in the longitudinal direction.

4. No wind is blowing on the runway

5. Aircraft is loaded to its full loading capacity

6. There is no wind blowing enroute to the destination

7. Enroute temperature is standard

#Corrections for Elevation, Temperature and Gradient:-

• Correction of Elevation:

Basic runway length is increased at the rate of 7% per 300 m rise in elevation above the Mean Sea Level (MSL).

• Correction for Temperature:

Airport Reference Temperature (ART) = Ta + (Tm-Ta)/3

where,

Ta = Monthly mean of average daily temperature

Tm = Monthly mean of max daily temperature for the same month of the year

Now, there should be 1% for 1 degree rise in airport reference temperature above the standard atmosphere temperature at the elevation

Standard Atmospheric Temperature (SAT) = 15 - 0.065(elevation)

Or Else,

Total correction for elevation plus temp = 35% of basic runway length

• Correction for Gradient:

1. Steeper gradient results in greater consumption of energy and as such longer length of runway is required to attain the desired ground speed.

2. After having been corrected for elevation and temperature should be further increased at the rate of 20% for every 1% of effective gradient.

3. Effective gradient is defined as the maximum difference in elevation between the highest and lowest point of the runway divided by the total length of runway.

No correction is needed to landing for temperature and gradient.

Runway Geometric Design

• Runway Width:

ICAD recommends the percent with varying from 45 m to 18 m for different types of airport.

• Safety Area:

This should be paved area plus the shoulder on either side of runway plus the area that is cleared, graded and drained.

It should be at least 150 m for A,B,C type airport, 78 m for D and E types and for instrumental runway it should be at least 300 m.

• Transverse Gradient:

This is required for quick drainage of surface water

1. For A,B and C type of Airport 1.5%

2. For D and E type of Airport 2%

• Longitudinal Gradient:

1. For A,B,C type of Airport = 1.5%

2. D and E type of Airport = 2%

• Rate of Change of Gradient:

This should be limiting to maximum for 0.1% per 30 m length of vertical curve for A and B type, 0.2% for C type. and 0.4% for D and E type of airports. Vertical curves are generally not necessary if change in slope is not more than 0.4%.

• Sight Distance:

Any two points 3 m above the surface of runway should be mutually visible from a distance equal to half the runway length for A,B and C type of Airport.

For D and E type of Airport the points should not be obstructed.