MRT trains move over half
the Singapore population every day, place to place, empowering the conduct of everyday activities. There is little margin for error. SMRT – one of the two rail operators in Singapore – harnesses technology to ensure reliability.
In the last 30 years, ridership on the network, and correspondingly train frequencies, has increased tremendously. Old maintenance regimes for hardware are no longer adequate; new ways of assessing risks are needed – particularly, the ability to track train conditions so that emerging issues can be rectified early before they cause problems. For which, sensors play a significant role – both in predicting future failures as well as enabling effective data collection.
Sensors as a Monitoring Device
Trains draw power from the power rail through train-mounted current collector device (CCD) shoes. If the power rail sags below an acceptable limit, a power disruption could be triggered. The sensors, which sit in tandem with the CCD shoes, measure the dynamic readings and ensure that the data, with variations as small as 1mm, are within safety thresholds. These mechanical sensors, which are currently mounted on five trains on the North-South and East-West Lines (NSEWL), monitor the condition of the power rail during service hours. In 2016, about half of all SMS alerts that were triggered prompted immediate rectification work.
Employing Sensors for “Sense-making”
All data collected weekly is plotted against data from previous weeks, allowing identification of preventive maintenance required for power rail segments. These sensors supplement the multifunctional vehicle (MFV) that circulates the entire track during engineering hours between 1am and 4am, collecting information on 16 parameters relating to the track and the power rail. One MFV takes about four to six months to cover the entire NSEWL.
The Future Role of Sensors
Using the latest available technology, including sensors and analytics, is a major part of the strategy to build a future-proof rail system. For that reason, a sensor system that will be able to watch for anomalous vibrations as proxies to track and train conditions is currently under development. When the system is completed, new sensors placed along two to four sectors of the track and on two trains, will provide a running system health check on up to six parameters, including if and how much the rail has been worn down, and if there are cracks or chips on the track. On trains, details like the level of suspension or the condition of the wheels will also be monitored to positively impact the comfort of rides.
Beyond measuring critical systems, SMRT Trains is working to move to a stage where everything can be measured and resources can be better optimised while ensuring fewer delays and disruptions for commuters in the long run.