First Two Rail Cracks Different from the Last Two
For the first two incidents that took place on 29 April and 18 May, these cracks were clearly on the welded portions of the rail. The cracked rails have been sent to the Institute of Rail Technology in Monash University for assessment. Our preliminary assessment is that the cracks were caused by impurities in the welding materials. The third rail crack that was identified on 30 May between Yio Chu Kang and Ang Mo Kio and the one that occurred between Tiong Bahru and Outram Park on 31 May were markedly different from the first two. The cracks occurred on a non-welded portion of the rail.
Anticipating More Cracks in Future but Safety NOT compromised
The latter two cracks are symptomatic of an ageing network. While we do not preclude such incidents from happening in the future, we assure the public that systems are in place to ensure that safety of passengers is not compromised. The signalling system that identifies track faults when there is a rail crack, thus halting the train is still the most reliable safety feature and this ensures that we are able to attend to any rail crack incidents in future and rectify them with immediacy and precision without compromising passenger safety. We have a high level of confidence in detecting a rail crack.
Our recovery has been prompt and precise. From the time of detection to putting in the fish plates and G-clamps, we have delivered the reinforcement in under 60 minutes, minimising interruption to commuter travel.
We have also been communicating proactively and offering real time updates to passengers and the general public through station, in-train announcements and Twitter and Facebook updates.
Implementing Short-Term Measures in terms of Maintenance
As a short term measure, SMRT will make extensive checks across critical sections of the rail a key priority and reallocate resources to improve preventative checks on identifying potential rail cracks and immediate replacement of affected portions of rail.
Primary focus will be on curved tracks along the North-South and East-West lines (NSEWL), which are particularly susceptible to rail cracks. A total of 246 joints will undergo extensive ultrasonic tests and checks.
In addition, we will further step up on the examination of the condition of track components including bolts, base plates, rail pads and pandrol clips.
Accelerating Re-sleepering and Raising Threshold of Rail Change
In this instance, the acceleration of the sleeper replacement programme is absolutely critical. SMRT will also be raising the threshold for rail change out, from the current 14mm limit to 12mm, in order to better carry out more proactive rail replacement.
Facing Some Constraints
SMRT faces certain constraints in carrying out the extensive works required for detection of potential cracks and change of rails. This includes spatial capacity to facilitate the rail change out. At least 60m of space is required while there is provision for only 18m currently. SMRT is working with the Land Transport Authority (LTA) on its requirements in order to improve the rate of replacement works.
Emphasising System Overhaul is Critical
While the plan is in place to commence daily renewal work along the NSEWL from July 2013 with the full turn out expected by 2017, we believe that the network change, which is currently underway, is the long term solution to the problem. The NSEWL is ageing and clearly showing signs of wear and tear. With increased usage of the rail due to high frequency, the wearing out will be faster hence we need to accelerate our network overhaul.
SMRT Corporation Ltd (SMRT) is Singapore’s premier multi-modal public transport operator. SMRT serves millions of passengers daily by offering a safe, reliable and comprehensive transport network that consists of an extensive MRT and light rail system which connects seamlessly with its island-wide bus and taxi operations. SMRT also markets and leases the commercial and media spaces within its transport network, and offers engineering consultancy and project management as well as operations and maintenance services, locally and internationally.