The Impact of Geological Uncertainties on Contract Management on Construction of Highway Tunnel in Himalayas: A Case Study Kumar Anil1, Kapil Manish1, Singh L.M.2, Goyal P.2 1DGBR, New Delhi 2Rohtang Tunnel, Manali, HP Online published on 20 April, 2019. Abstract Rohtang Tunnel is being built under the Rohtang Pass in the Eastern Pir Panjal range of the Himalayas on Leh-Manali Highway. With 8.8 km length, the tunnel will be one of the longest road tunnel in India and the world's longest tunnel at an altitude above 3, 000 m and will reduce the distance between Manali and Keylong by about 60 km. The tunnel is at 3, 100 m elevation whereas the Rohtang pass is at 3, 978 m elevation 51 km away from Manali. The pass receives heavy snowfall and blizzards during winter months and is open for road traffi c for only four months in a year. The most challenging task is to continue the excavation during heavy snowfall in winter which is being done from both ends. However, the north portal is not accessible during winter as Rohtang pass closes during the winter and the excavation is being done only from the south portal. There are more than 46 avalanche sites on approaches to the tunnel. Other challenges to the progress of the tunnel include diffi culties in heavy ingress of water by Seri Nallah (as much as 3 million litres per day in June 2012) from unstable rocks that slows the blasting and digging, requires constant 24x7 dewatering and costlier treatment and slowed the progress of excavation from 5 metre per day to just half a metre a day which was not considered at the time of tendering. This paper focuses on how geological uncertainties in Himalayas were tackled successfully by taking decisions in continuation of work in complex geological conditions and tectonic settings which have not only paused problems at each step but also impacted overall cost and completion time of the project. It also showcases how these problems have been addressed at contract management point of view. Moreover, this paper analyzes the problems and solutions of different ways, sums up the experiences, and provides some guidance in the construction of tunnels under similar conditions in mountainous areas. Top Keywords Himalayas, Seri Nallah, geological uncertainties, water ingress, contract management. Top |