Srinagar: The Rs 4,000-crore Rohtang Tunnel, the world’s longest motorable roadway at an altitude of over 3,000 metres, is ready for opening next month following the completion of civil works that began a decade ago.

The tunnel will be opened by Prime Minister Narendra Modi by mid-September, Satish Paretkar, Director of Hydro & Underground business unit at Afcons told PTI.

A joint venture of Shapoorji Pallonji Group-run Afcons and Strabag of Austria won the Engineering Procurement & Construction (EPC) tender for Rs 1,458 crore from Border Road Organisation in 2009.

The cost of the project has crossed Rs 2,500 crore now, he said. The civil works started in 2009 and was to be completed within 6.5 years.

Paretkar said the exact date of opening of the tunnel is yet to be finalised.

The 9.02 kilometres-long Atal Tunnel, named after former Prime minister Atal Bihari Vajpayee, passes under the Rohtang Pass in the eastern Pir Panjal range on the Leh-Manali highway at an altitude of 3,060 metres at the lowest and 3,078 metres at the peak.

The tunnel is 10.5 metres wide and has a height of 5.52 metres and a car can zip through at 80 kmph.

According to Paretkar, the horseshoe shaped single-tube, double-lane tunnel has many firsts.

With a length of 9.02 km, it is the longest in the world at an altitude of over 3,000 metres or 10,000 feet mean sea level, he said.

Further, it is also the country’s first tunnel to have an escape tunnel within the main tunnel because of the topography.

Globally, escape tunnels are built separately along the main tunnel.

This is also the first tunnel to deploy the Rowa flyer technology, which allows engineers to work at inverted levels, he said.

Paretkar said the delay in completion of the tunnel was mainly due to the 410-metre long Seri Nalla, a brook.