Contractor drills longest railway tunnel

Journalists take pictures inside the railway tunnel at Ngong Kajiado County

KAJIADO, KENYA: A Chinese company contracted to construct the Nairobi–Naivasha SGR Phase 2A, has successfully drilled the longest railway tunnel in East Africa.

China Communications Construction Company (CCCC), has drilled a 4.5 km tunnel, in Ngong,  Kajiado County  that has been designed as a single-track railway tunnel with a clearance height of 9 meters and a width of 7 meters.

CCCC engineers used the New Austrian Tunneling Method (NATM) of drilling and blasting to build the tunnel. This is the first time that such a method has been used on such large scale in Kenya, according to Mr Steve Zhao, the CCCC Kenya SGR Project Spokesperson.

The tunneling method is economical, efficient and has strong adaptability for different geological and groundwater conditions. What is more, the method controls surface collapse effectively, and enhances the working environment during construction.

For the first time, local and international journalists were shown inside the tunnel to take pictures.

Speaking separately to the Standar during a tour of the tunnel that was commissioned on Tuesday, Steve Zhao said 146 refuge holes of different sizes have been built within the tunnel to allow maintenance workers to take cover as the train approaches.

“There is one large refuge hole set up every 150 meters in the tunnel, and one small refuge hole set up every 30 meters in the tunnel,”  Zhao explained.

A 533-meter wide emergency rescue channel has also been built within the tunnel, to allow for vehicle access in case of emergencies.