Mumbai Metro starts structural health monitoring

The Metro is the only one in the world with real-time monitoring of a cable stay railway bridge.
Aging, deterioration and extreme events like earthquakes and hurricanes can take a toll on roads, bridges and other structures.
With damage and defects often invisible, and to alert the authorities to potential problems and even impending catastrophic failure, the Mumbai Metro One has commissioned the world´s first real-time advanced Structural Health Monitoring System (SHMS) for Asia´s tallest cable stay bridge across the Western Express Highway (WEH). The system is supplied, installed and monitored by an Indian subsidiary of a company from Switzerland, Mageba, a world leader in cable stay bridge monitoring systems. It monitors the health of the bridge on a real-time basis. An MMOPL spokesperson said, ´The cable bridge is a marvel of engineering, and the structural health monitoring system (SHMS) is unique to a mass rapid transit system (MRTS).´

Since Mumbai Metro carries well over three lakh commuters daily, the safety of the structure is paramount. State-of-the-art SHMS help Mumbai Metro to get information on the condition of the structure on a real-time basis. The system reiterates our commitment to the highest safety standards in our operations.

How it works
The permanent bridge´s surveillance system is an assembly of 25 sophisticated electronic sensors, which are imported from Europe and installed at various strategic parts of the bridge for the purpose of continuously measuring and recording critical physical parameters, consequently assessing the actual conditions of the structure. The SHMS generates an alarm if any of the determining critical structural parameters are exceeded beyond the threshold. It makes use of the natural frequencies of the cable stay bridge to provide valuable knowledge about the structural condition. The ROBO®CONTROL permanent system is equipped with electronic devices – cable accelerometers, tri-axle accelerometers, inclinometers, displacement sensors, laser deflection sensors, strain gauges, structural temperature sensor, wind direction & intensity sensor, air temperature & humidity sensor and data acquisition system. The data is dynamically acquired in order to analyse vibrational behavior. The data so collected is evaluated online and representative results are transmitted to the monitoring server. The data-transmission from the monitoring system is realised via Internet technologies. There will be a permanent control room in the WEH Metro Station for this. However, the system can also be accessed digitally from everywhere in the world.

The technology is designed by France-based Systra, proof checked by TUV, Germany; the system supply and construction is by VSL, and real time monitoring by Mageba, Switzerland, respectively.

QUICK FACTS

• The three-storey high mid-air cable stay bridge over the busy WEH was constructed from either side in the air using imported machinery.
• A 40,000 kg form traveller was built without stalling the busy traffic on Jog Flyover even for a minute.
• The structure has a 83m long main span, 39m high pylon and a 19m high bridge deck.
• It is the world´s first Metro railway cable stay bridge fitted with a ROBO«CONTROL permanent real time bridge monitoring system.