Pakyong Airport — An Engineering Marvel

IndraStra Global

Pakyong Airport — An Engineering Marvel

By IndraStra Global News Team

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India (AAI)

On September 24, 2018, India's Himalayan state of Sikkim got its first airfield - "Pakyong Airport" - at the Percheda top, 30 km south of Gangtok, the capital city of the state. The airport was officially inaugurated by Indian Prime Minister Narendra Modi, almost ten years after the Government of India's Cabinet Committee on Economic Affairs (CCEA) cleared construction of a greenfield airport at Pakyong in Sikkim (in October 2008).

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India (AAI)

The airport's perimeter is situated at 4700 ft and spread over 200+ acres. The newly-built airport is one of the five highest airports in India. It is also the first greenfield airport to be constructed in the Northeastern Region of India, which also happens to be the 100th operational airport in the country.

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India

Image Attribute: Aerial view of Pakyong Airport's 3,000 sqm passenger terminal / Source: Airport Authority of India (AAI)

The airport has integrated structures comprising an Air Traffic Control (ATC) tower-cum-fire station, two sophisticated CFT, one terminal building for passengers (3,000 sqm, with a capacity to handle 50 inbound and as many outbound passengers), high-intensity runway lights, and parking for over 50 vehicles.

Image Attribute: Aerial view of Pakyong Airport / Source: Airport Authority of India

Image Attribute: Aerial view of Pakyong Airport's 3000 sqm passenger terminal / Source: Airport Authority of India (AAI)

The airport has a 1.75 km runway with a width of 30 meters. It has a 116-meter-long taxiway connecting it to an apron measuring 106 meters by 76 meters that can simultaneously accommodate two ATR-72 aircraft.

Image Attribute: At the runway of Pakyong Airport / Source: Airport Authority of India (AAI)

Image Attribute: At the runway of Pakyong Airport / Source: Airport Authority of India (AAI)

An Engineering Marvel


In the year 2009, India's Punj Lloyd Group won a US$ 37 million (₹264 Crores) contract to build this greenfield airport. The land for the airport was carved from the mountainside using massive geotechnical "cut and fill" engineering technique. The material cut from the uphill slopes was then used for the downhill fill operations, thereby creating the platform for the runway.  

The actual scope of work involved excavation of 100 m depth and earth filling of slopes of 80 m height, stabilized with "Geogrid Reinforced Retaining Wall". A large volume of earthwork - 65 lac m3 - which involved blasting in hard rock apart from soft rock and soil. To protect the environment, excavated slopes of 100 m height are planted with local species of flora.


Architectural Drawing of Pakyong Airport, Sikkim, INDIA
The Initial Architectural Drawing of Pakyong Airport, Sikkim, INDIA / Kindly, do note, the final height of "retaining wall" is 80.83 m / Source: Airport Authority of India (AAI)

Composite reinforced soil technology was used to retain the high embankments by reinforced soil walls. In places where there was space constraint, the slope was stabilized by 3m high gabion retaining walls, which being free-draining, also provided a drainage path for stormwater.

The management of stormwater run-off on the project was a vital component of overall planning. Constraining the natural passage of water in any way could cause a build-up of porewater pressure within the reinforced soil walls (potentially affecting stability) or reduce the water supply to the population downstream of the airport. Of the 11 Jhoras (natural streams) identified within the site boundary, 9 crossed the runway alignment and had to be canalized. Water control structures ultimately fed 4 concrete culverts running perpendicular to the runway which discharge through the face of the reinforced soil ParaMesh structures.

Image Attribute: The 3-D imaging of Pakyong Airport / Source: Airport Authority of India (AAI)

Image Attribute: The 3-D imaging of Pakyong Airport / Source: Airport Authority of India (AAI)

The vulnerable cut slopes were covered with erosion control blankets, Biomac® C, made of coir. The Biomac® C minimizes the surface erosion due to rain and surface run-off and additionally promotes vegetation re-establishment. Thus, the cut slope quickly stabilized and blended with the beautiful surroundings.

The runway strip was planned in a North-South (N-S) orientation cutting into an existing hill with a natural slope from the West (uphill "cut" portion) to East (downhill "fill" portion). Since a 150m wide planar surface was required for the construction of the runway and airport structures, a vast "cut and fill" construction was determined to be the most efficient construction method.