The 110km-long Sharjah to Kalba road provides a vital west-east link across the UAE’s peninsula.
The scheme includes a 1.27km tunnel – the longest in the Middle east – that passes through the mountain between the Al Madeeq and Al Qula’ei valleys. Designed by Halcrow, the tunnel shortens the distance between the central zone of the peninsula and the east coast by 30km
The link between the Sharjah City Ring road and the town of Kalba on the Emirate’s eastern coast has been a long term commitment for Halcrow lasting over 12 years, involving 10 major road construction projects with a combined value of $170m. The route includes 6 major and 5 minor interchanges, a 1.2km long bored rock tunnel and a 200m reinforced concrete cut and cover tunnel. Halcrow provided the design, the construction management and the supervision of all contracts.
The route extends through 50km of desert dunes and gravel plains before linking to an existing road at the village of Shawkah. The existing single carriageway road was improved and widened along 21km of its length through mountainous terrain as far as the village of Munaiy. From here 26km of new dual carriageway has been constructed through difficult mountainous terrain to reach the town of Kalba. This section required tunnels at two locations and extensive rock cutting and slope stabilisation work.
The tunnel has an overall width of 13.5m and height of 9.7m, with a total excavated face area of 110m2. . It is 1170m long and will currently accommodate a single carriageway, bi-directional road. The design of the tunnel allows future construction of a second bore to accommodate a second carriageway.
The tunnel was excavated in hard rock by drill and blast methods. The rock type is gabbro, a coarse grained, basic igneous rock. Permanent support to the tunnel was provided with sprayed concrete (up to 250mm thick), steel rockbolts (4m long) and steel lattice girders. The tunnel also has an unreinforced secondary concrete lining along the full length. A drainage system consisting of a fleece geotextile and waterproof membrane was also provided in the worst ground conditions (Class V & IV).
Halcrow also provided technical advice on the provision of tunnel services, including permanent ventilation, fire safety, security system and lighting.
Innovative Design
Certain sections of the route were constructed against a demanding programme with the contractor being appointed at an early stage in the development of the design. The challenge for Halcrow was to deliver the design to meet the contractor’s construction schedule.
The design took advantage of Halcrow’s international capability. The roads drainage and geotechnical designs were produced using the available capabilities of staff based in Sharjah, whilst staff in the UK were used for specialist inputs associated with the preparation of tender drawings, specifications and a bill of quantities for the tunnel works including the reinforced concrete cut and cover portal structures.
This tunnel was the first bored rock tunnel in the UAE. Whilst the techniques are established, this was the first application of them in this environment.
Benefits
The highway provides an important link through the Hajar Mountain range between the west and east coasts of the United Arab Emirates. It will significantly reduce journey times, improving access to the eastern part of the Emirate of Sharjah and to the communities of Shawkah, Munai and Gillay along the length of the route and thus, enhancing tourism in the Emirate.