Chinese contractor drills longest railway tunnel in East Africa

NAIROBI, Sept. 25, (Xinhua) – China
Communications Construction Company (CCCC) has drilled the longest railway
tunnel in East Africa, the company said Monday.

The tunnel is part of phase 2A of the Standard
Gauge Railway (SGR) that runs from the Kenyan Capital city of Nairobi to
Naivasha town.

An Aijun, general manager of SGR project head
office at the CCCC, said that during the excavation, the project team overcame
the challenges of water leaks, uneven pressure, shallow-depth excavation,
surrounding rocks, structural fault-line, and oil pipeline protection.

“With a total length of 4.5 km, the Ngong
tunnel is currently the longest tunnel in East Africa and the dominant work in
SGR Phase 2A,” An said during celebrations to mark the breakthrough of the
Ngong tunnel.

The Phase 2A which extends for about 120 km is
set to be completed in 2019.

The 4.5 kilometre Ngong tunnel has been
designed as a single-track railway tunnel with a clearance height of nine
meters and a width of seven meters.

CCCC engineers used the New Austrian Tunneling
Method (NATM) of drilling and blasting to build the tunnel and it is the first
time that such a method has been used on such a large scale in Kenya.

The tunneling method is economical, efficient
and has strong adaptability for different geological and groundwater
conditions.

The method is preferred because it controls
surface collapse effectively, and enhances the working environment during
construction.

An said the construction team addressed the
technical difficulty in designing and constructing in the Great Rift Valley to
ensure a safe breakthrough of the tunnel and this means that the SGR Phase 2A
has entered a new stage, laying a solid foundation for inauguration next year.

The general manager said that with quality as
a foundation and safety as a lifeline, they shall maintain an all-round quality
control system in the source, process, methodology and management, and enforce
strict safety management at all procedures.

“We will continue to protect the
environment, implement local contents, and participate in social welfare,
bringing real benefits to the local communities,” he added.

“Together with all our Kenyan partners,
and building on what has been achieved at the FOCAC (Forum on China-Africa
Cooperation) Summit in Beijing, we shall construct a time-honored railway that
will stand the test of time and operations, achieving greater success in a new
era between our two nations,” he added.

According to Steve Zhao, the CCCC Kenya SGR
Project Spokesperson, 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.

“We have reserved space to install fans
within the tunnel. Six jet fans can be installed to ensure air ventilation once
the tunnel is operational,” added Zhao.

He revealed that about 600 workers and
engineers worked tirelessly overcoming all odds for 24 months to accomplish the
engineering marvel.

Michael Waweru, chairman of board at the Kenya
Railways, said the SGR is one of the most important transformational projects
for the railway and entire transport sector in the region.

“It is an ambitious undertaking by the
government of Kenya envisioned to revolutionize the social economic development
of the country,” Waweru said.

The chairman said it is expected that as a
result of construction of the SGR line, it will lead to an upsurge in
development in the towns along the corridor, ease transportation of their
resources and foster sustainable development patterns.

GNA

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