Photo: COWI

Replacement of Sitra Bridges 

The Sitra Bridges linking Sitra and Manama in Bahrain are to be replaced as they have reached the end of their service life and can no longer cope with increased traffic volumes.

The causeway and bridges between Sitra and Manama in Bahrain are one of the most important traffic links in the country's road network. The dual two-lane roads and the at-grade junctions cannot cope with the heavy morning and afternoon rush hour traffic loads, which are exceeding 6,000 vehicles per hour.

Built in the 1970s, the Ministry of Works and Housing in Bahrain has now concluded that they have reached the end of their service life as ongoing concrete deterioration of the two marine bridges has reached an extent where they can no longer be repaired.
Photo: COWI


Long service life

The new structures will be predominantly post-tensioned concrete. According to the client's terms of reference, the structures must be designed and constructed for a service life of 120 years – a demanding task in the extremely hostile marine environment. These requirements were met through extensive use of stainless steel reinforcement in the most exposed parts of the concrete structures.

Traffic flow must be maintained

Project-managing the implementation of the new structures for COWI is Mogens A. Hviid. "A key requirement for the client has been to maintain the traffic without interruption during the construction," he said.

Hviid added, "There are also numerous utilities that need to be maintained, such as gas pipelines, electricity high-voltage cable, water mains, sewerage pipes, telecommunication to name a few. The requirement to maintain the very heavy traffic and all these services uninterrupted during all phases of the construction means that this project can be considered a true nightmare for the contractor."

The solution

Maintaining traffic flow and services will be achieved by building the new bridges and utility conduits alongside the existing ones, then switching from the old to the new. Disruption is expected to be limited to a few hours during switchover.

The construction works are due to commence this autumn and scheduled to be completed by mid-2009.

By Martyn Glanville
Published: 12.09.06

Facts about the project 
  • The south bridge is 400 metres long and 55 metres wide
  • The north bridge is 200 metres long and 58 metres wide
  • Both are constructed with post-tensioned concrete
  • The most exposed parts have been reinforced with stainless steel to combat the effects of the extreme marine environment