It will build three tunnels with a total length of 3.3 kilometres under Riyadh Air Base, which is in the centre of the capital.

Two tunnels will each measure 800 metres in length, with the third running for 1.7km.

The tunnels will extend two major road arteries under the airbase: Aruba street, which runs from east to west, and Abu Baker road, which runs north to south. The contract will also cover associated works such as the construction of groundwater and storm-water pumping stations.

The client, Arriyadh Development Authority, has set a completion date of July 2012 for the work.

The authority hopes the project will alleviate traffic congestion within the capital. Traffic is currently forced to drive around the airbase, which covers an area of about 5 square kilometres.

Almabani submitted the lowest bid after Arriyadh tendered the contract in November last year. The other bidders were Shibh al-Jazira Contracting Company, Saudi Oger and Saudi Binladin Group, all local. Beijing-based China Harbour Engineering Company also submitted a bid.

Also in November last year, the Royal Saudi Air Force awarded Almabani a SR125m construction contract for other work at the Riyadh Air Base, which is used for