It is thirty-two years since Bahrain’s capital Manama was first linked to Sitra Island by two road bridges; a $265m replacement of the Sitra crossings is now underway – currently the largest bridge project in the kingdom.

The scheme will see the dual-lane north and south marine bridges replaced. More than 6,000 vehicles an hour are understood to be using the 3.2km crossing that passes over Tubli Bay.

“The need to replace the existing bridges stemmed from the fact that they have reached the end of their service life and it is no longer economically feasible to maintain them,” says Al-Salah.

The new bridges will increase capacity by carrying three lanes in each direction instead of two, and will each have a hard shoulder that can be converted to a fourth lane in the future.

“The existing bridges have deteriorated so badly that heavily loaded vehicles are generally banned from crossing them. The bridges are no longer able to accommodate the increasing traffic that uses them; this is manifested by long traffic queues that are frustrating to road users and that have a negative impact on the movement of goods and services,” he says.

Construction of the new crossings began in September 2006 and contractor Gamuda Bhd of Malaysia has encountered some interesting challenges to date. “Huge deposits of silt were discovered by the contractor at the location of the new southern marine bridge. These deposits reached six metres in depth at some locations and were not identified by the design consultant and not shown in the construction drawings. All those silt deposits had to be removed first at additional cost and time.”

Further delays have also been caused by the complex network of services running beneath the Umm Al-Hassam (UAH) road junction that links Manama into the bridges. “Buried beneath the junction are numerous utilities: 220kV, 66kV and 11kV electricity cables, water pipelines, storm water pipelines, sewerage pipelines, natural gas pipelines. Most of these were laid down more than a quarter of a century ago, and drawings that show their locations are inaccurate and in several cases non-existent,” explains Al-Salah.

A sewerage pipeline that was discovered to be in the wrong place when the contractor started work caused major delay because it had to be diverted.

The Bahrain Electricity and Water Authority imposes a ban during the summer months on working on or in close proximity to electricity cables. “This adds a constraint to the contractor programme and may lead to delays if the required work outside the ban period cannot be completed in a timely manner,” says Al-Salah.

These delays and extra work have pushed the final cost to around $265m; original estimates placed the project value at $200m. However, the structures are predicted to last considerably longer than the last crossings which have operated for less than 40 years. “The structures for the Sitra causeway and the junction are designed for a life span of at least 100 years in an environment known for its severe climatic conditions”

And the benefits for business are wide-reaching, as the crossing will also link in to the Qatar-Bahrain causeway. “Following the completion of the Qatar-Bahrain causeway, this segment of the road network will be the main access to Manama for those coming from Qatar. Enhancing this strategic segment of the road network in Bahrain will have significant benefits to the economy of the country by easing the movement of people, goods and services not only on a local scale, but also on a regional one.”