A new dual carriageway linking the settlements of Diftah and Shis is being cut through the Hajjar mountain range of the United Arab Emirates. This mountain range stands between the city of Sharjah and one of the UAE’s most important ports.
The road cuts through slopes, beneath the mountains and across wadis (dry riverbeds that are prone to flash flooding). The road, which is part of a strategic project to connect Sharjah to the major container port of Khor Fakkan on the Gulf of Oman coast, has seen the construction of the biggest rock tunnel in the UAE. The construction of the 1.3km twin-bore dual-carriageway road tunnel through rock has been a challenging part of this project.
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The container port of Khor Fakkan is increasingly important for Sharjah and the UAE. The port is the arrival point for a variety of goods that are distributed via Sharjah throughout the Emirates. The existing road network that links the Khor Fakkan container terminal to Sharjah’s Inland Container Depot loops to the south of the mountain range and passes through Fujairah. Construction of a 26km road through the mountains virtually halves this 54km section of the route between Khor Fakkan and the city of Sharjah.
The 9km section between Diftah and Shis which includes the 1.3km tunnel is the first phase of a future 26km route.
Tunnelling through the rock has been a slow and lengthy process. Hard rock is not the only thing Halcrow’s team has had to endure. Another major obstacle is the extreme desert heat. “There is not a breath of wind up there in the summer,” says senior project manager Paul Cooper. “If you put your hand on a rock it will burn.”
Innovations
The tunnelling process adopts the New Austrian Tunnelling Method, a standard construction technique for rock tunnelling. The lining of unreinforced concrete provides a permanent supporting arch. Polypropylene fibres incorporated within the concrete mix provide fire resistance and minimise damage in the event of a fire by reducing explosive spalling of the material.
Benefits
An immediate benefit to the residents of Shis village will be realised upon completion of this project by providing a metalled road access to the village. Access to Shis is otherwise on unpaved tracks from the east coast through an enclave of the Sultanate of Oman.
The main benefit will be when the whole route between Diftah and Khor Fakkan has been completed, and every container truck will have each trip reduced in length by 28km.