Bridge monitoring for Turkish tunnel!

Sentez, the Turkish distributor of Applied Measurements were asked to design a bespoke bridge monitoring system for Turkey’s new rail tunnel - The Marmaray Project. This 76.3km long tunnel is the deepest immersed tunnel in the World and is regarded as the foremost challenging infrastructure project in Turkey.

Using Applied Measurements’ AML/SGD strain gauge displacement transducers, the tunnel provides a direct link between Halkalı on the European side of Istanbul, with Gebze on the Asian side. This modernised high capacity rail tunnel will carry up to an estimated 65’000 passengers per hour in 2015, increasing to a predicted 75’000 in 2025, saving commuters a 1 hour 15 minutes of travelling time (Figures from The Marmaray Project website passenger demand and planning.)

The Marmaray development team needed to monitor the displacement on the joints within the tunnel. To do this we created a bespoke bridge monitoring system using 3 off 50mmAML/SGD displacement transducers, forming a triaxial measurement of each joint. TheAML/SGD series of displacement transducers utilise strain gauge technology to convert the linear movement of the joints within the tunnel into an analogue electrical signal. TheAML/SGD series of displacement transducers were chosen for their excellent accuracy (0.1%), coupled with their high resolution and long-term stability, making them a perfect transducer for The Marmaray Project.

Applied Measurements’ 50mm higher accuracy AML/SGD linear variable displacement transducers were wired into a custom-made IP68 die cast enclosure. This IP68 enclosure housed 3 off SGA load cell amplifiers, protecting the amplifiers from moisture ingress. This provided the Marmaray team with an amplified signal enabling them to accurately monitor the displacement of the joints within the tunnel. These SGA series of load cell amplifiers are capable of delivering highly stable, high speed, industry standard analogue outputs, such as 0-10Vdc or 4-20mA, from very low-level input signals and are available next day delivery.

"Applied Measurements are proud to have been involved in such an important project for Turkey, said a company spokesperson. We hope to continue to assist with new and existing projects through our new Turkish distributor Sentez."