Marmaray Rail Tunnel Istanbul, Turkey (Flakt Woods, UK)

28 July 2016

Project value: 4.1 billion USD (Estimated figure)
Engineering at the heart of a project

Marmaray has been described as the project of the century, and the tunnel will connect two continents with the rail-tunnel running deep beneath the Bosphorus Straits. The tunnel consists of a series of earthquake-proofed immersed tubes, assembled from 11 sections, each as long as 130 metres (427 feet) and weighing up to 18,000 tons. These are placed down to 55 metres (180 feet) below sea level; making it the world’s deepest undersea immersed tunnel tube. When in full operation it is expected that around 1.5 million passengers will cross the Bosphorus Straits.

Acrefine Engineering is providing technical support to Flakt Woods, UK, who is supplying a range from their super-powerful Axial fans for eight shafts ventilating the new crossing. Measuring up to 2.8 (9 feet) metres in diameter, the fans will be capable of providing emergency ventilation in the worst-case scenario – a fire on a freight train more than a kilometre long.

Earthquake protection is a key factor in this scenario and Acrefine is assisting with expert advice and consultancy to achieve best practice. Beside the local Turkish code FEMA is also used for compliance with the latest international standards in seismic.

Seismic and anchor calculations are performed to provide secure mounting for the fans, which are classified as critical (life safety) equipment. New AS-AR-10000 reinforced type snubbers have been designed and manufactured to restraint the fans. Each fan will be mounted with four snubbers that are capable of resisting the high earthquake loads.