The landmark Yemen-Djibouti bridge crossing, which will link the two continents of Africa and Asia, has entered the detailed planning stage.

The road and rail crossing, dubbed the “Bridge of the Horns”, will span 27km at an estimated construction cost of $20-25bn. The bridge is a key component of Al-Noor Holding Company’s $200bn cities project in Yemen and Djibouti, comprising a new industrial city in each country.

US company L-3 Communications, project manager for Al-Noor, is currently in discussion with the Danish firm COWI over the feasibility and design of the ambitious project.

“We are going into negotiation now with them to determine how long it will take. This is the most complex of the two projects,” says Dean Kershaw, programme manager with L-3. “We need to undertake geo-technical studies to ascertain any unknowns on the sea floor and in areas where are going to build the approach to the bridge.”

COWI has already completed the sketch designs and they are going to work with L-3 on the preliminary designs of the bridge. The structure is expected to be a combination of causeway and suspension bridge, with four piers at 2.7 kilometre intervals. Due to the deep water in the Red Sea, the piers will have to reach 800m in height.

“The water can go down to 330 metres, which will make it the deepest bridge to be built in the world. The deepest at the moment is the Golden Gate bridge in San Francisco Bay at 75 metres. The bridge pylons will rival the height of the Burj Dubai” explains Kershaw.

Enzo Zoratto, chief strategic officer with US-based consultant DCK Worldwide, says the structure represents one of the toughest aspects of the whole project. “The bridge is the most technically challenging.” The next phase for the bridge, Zoratto adds, is to procure funding for the detailed design and then assess interest from design and build competitors.

The next key stage for the cities projects and the causeway development, according to Zoratto, is to engage with contractors capable of delivering projects of the scale planned by Al-Noor. The cities in Yemen and Djibouti are planned to be 1,500 km and 1,000km respectively.

The budget for initial expenditure in the first three years is expected to be complete in a matter of months, while the long-term budget is set to be finalised by October.