Paving a tunnel at altitude

A road tunnel stretch that opened for traffic in India in late 2020 is notable for several reasons. The new 9km Atal Tunnel is the world’s longest tunnel at an altitude of higher than 3,048m
Concrete Paving, Compaction & Testing / September 3, 2021
The road surfacing portion of the tunnel contract was carried out using an SF-2700 slipformer from Power Pavers
The road surfacing portion of the tunnel contract was carried out using an SF-2700 slipformer from Power Pavers

The tunnel connects the cities of Manali and Keylong and is located in the Himalayan mountain range, cutting the journey time from six or seven hours in the past to just two hours. Previously, the only route was through the dangerous Rohtang pass, which has many switchbacks, is prone to erosion, landslides, and is often covered by snow. The distance between Manali and Teling was 79km but the new tunnel has cut this by 46km. For the first 400m at each of the portals, the speed limit is 40km/h but in the rest of the tunnel length the speed limit is 80km/h, while overtaking is strictly prohibited on safety grounds.

Taking 10 years and US$430 million to build, the new tunnel can handle vehicles all year round. Named after former Indian prime minister Atal Bihari Vajpayee, this was a highly-publicised project. General contractor Afcons-Strabag decided against using a TBM and instead opted to use drilling and blasting to drive the tunnel. The design features an 8m-wide road carrying two traffic lanes, a 1m pedestrian sidewalk on each side of the road, an emergency egress pedestrian tunnel, state-of-the-art ventilation system, regularly spaced telephones, CCTV cameras, and fire hydrants.

The tunnel was surfaced using a Power Paver SF-2700, with the paving work having commenced in February 2019. Afcons-Strabag partnered with PH Infratech, which supplied the SF-2700 and paving crew.

Irinder Singh Ahluwalia, Partner, PH Infratech, explained, “The SF-2700 machine was very easy to move inside the tunnel, operating in the tightly confined space. They also selected it because of the low profile of the machine. The tamper system and edge overbuild helped the edges to be very precise despite variations in slump. The belt finisher also aided the finishing crew. Finishing inside the deep tunnel was a tough job, and the machine minimised the handwork.”

Based in Gurgaon, Haryana, PH Infratech has two concrete slipformers in its fleet, with a Power Paver SF-1700 in addition to the SF-2700. The machines were supplied and supported by the Indian dealer for Power Curbers, Allen Buildwell.

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