Part of the construction of the Nairobi-Naivasha SGR Phase 2A which will be Kenya’s first and longest railway tunnel at the Ngong Hills will be finalised in August.
China Communication Construction Company said it has finished half of the 4.5-kilometre tunnel, “digging from three points to cover 2.5 kilometres of the 4.5 kilometres tunnel.
Steve Zhao, the SGR Phase 2A spokesperson, said their engineers have been making efforts to make sure that the section is finalised within five months by working on the tunnel from the entry point of the locomotive, the centre, and the exit of the tunnel.
“So far, 1.2 kilometres are complete from the exit end, 0.8km from the entry side of the tunnel and 0.5km from the mid-section. The construction is taking place simultaneously to ensure that we complete all the work within the stipulated time,” Zhao said.
Section Office Number One is the team responsible for constructing the tunnel. It has more than 3,300 staff with most of them constructing on the tunnel.
“There is a shift programme for the workers, so that the work goes on non-stop 24 hours,” Zhao stated.
The design of the tunnel is a single-track railway tunnel with a width of 6.4 metres and a clearance height of 7.6 metres. During construction, the contractor has used the 3-bench 7-step excavation method.
Zhao also said workers’ safety during construction is important. That is why all workers are supposed to wear protective gear. “In addition, the air inside the tunnel is sampled and analysed monthly to ensure workers are not exposed to harmful gases.” He also said only male employees work in the tunnel while female workers construct other sections.
Other two tunnels will be constructed along the 120 kilometeres stretch of the Naivasha-Nairobi SGR route measuring 2.64 kilometeres. The two tunnels will be complete within 2019.