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Release of Report of COI into 15 and 17 December 2011 MRT Disruptions

04 Jul 2012 News Releases

1.     The Committee of Inquiry (COI) into the Disruption of MRT Train Services on 15 and 17 December 2011 submitted its report to the Minster for Transport on 3 July 2012.

The incidents of 15 and 17 December could have been prevented

2.     The COI's key findings of the technical causes and the most likely sequence of events leading to the MRT disruptions on 15 and 17 December 2011 are summarised as follows. More details are available in Annex A.

        a.15 Dec incident: The incident on 15 Dec 2011 was initiated by a defective fastener on one of the Third Rail Support Assemblies (TRSAs). This caused the claw of that TRSA to dislodge and the third rail to sag. Although trains remained able to pass the sag, it rendered the two adjacent TRSAs more vulnerable to vibration and over time, these two TRSAs, which insulators were coincidentally also defective, failed gradually. The third rail then progressively sagged further. In the evening of 15 Dec, the third rail sagged beyond the tolerance limit of the trains Current Collector Device (CCD) shoes, damaging the CCD shoes on trains passing the incident site. Some trains stalled after passing the site as they were no longer able to draw sufficient power from the third rail. At the incident site, multiple trains impacting the sagging third rail eventually caused three more claws to dislodge, such that a stretch of the third rail came to rest on the track-bed. This segment of the track then became impassable to all trains.

        b.17 Dec incident: The COI attributes the incident on 17 Dec 2011 to one or more possible rogue trains that suffered not easily detectable CCD shoe damage when it/they passed the 15 Dec incident site as the third rail was progressively sagging. The damaged CCD shoe(s) of the rogue train(s) destabilised the third rail system at other locations along the North-South Line on 16 Dec, causing one third rail claw on the south-bound track between Newton and Orchard stations to dislodge and the third rail to sag. Unfortunately, SMRTs checks in the suite of the 15 Dec incident and in the engineering hours of early morning 17 Dec failed to detect the damaged CCD shoe(s) on the rogue train(s) and the sag. On 17 Dec, Train 119 made unusually forceful contact with the third rail at the incident site, causing an adjacent claw to also dislodge. With two adjacent claws dislodged, the third rail sagged further and caused damage to the CCD shoes of Train 119 and the trains that passed after it. Some of these trains subsequently stalled as they were no longer able to draw sufficient power.

3.     The COI has also identified several factors that contributed to the incidents:

        a. Defects on train wheels that resulted in severe vibration;
        b. Gauge fouling, or contact with the third rail system by passing trains due to the separation between the third rail and the running rail being smaller than it should have been;
        c. Design of the current third rail claw which makes the claw susceptible to dislodgement;d.Shortcomings in maintenance work culture at SMRT; and
        d. Shortcomings in maintenance and monitoring regime, especially in the context of ageing assets.

4.     The COI concludes that both the 15 and 17 December 2011 incidents were preventable, had adequate maintenance measures and checks been carried out.

5.     With regard to incident management of the two disruptions, the COI's view is that SMRT exercised due prudence with regard to commuter safety. However, the overall incident response was skewed towards train safety and operations, and paid inadequate attention to the well-being of passengers in stalled trains and stations.

COI recommends measures to address engineering and maintenance inadequacies, and calls for significant improvement to incident management

6.     The COI has made a number of recommendations pertaining to engineering and maintenance issues, as well as incident management. These recommendations are summarised in Annex B.

7.     The recommendations pertaining to engineering and maintenance issues focus on prevention and detection of future problems related to the third rail system and the trains; and on improvements to the overall maintenance regime and regulatory framework. On incident management, the COI has called for greater clarity in the roles of, and for improved coordination between, the various stakeholders; improvements to various aspects of the incident management plan with emphasis on passenger well-being; and improvements in incident management readiness.

8.     The COI has expressed confidence that the recommendations in the report, when carried out, will reduce the likelihood of similar occurrences in the future, and that future incidents, should they recur, will be better managed.

Ministerial Statement will be delivered in Parliament to respond to the findings and recommendations of the COI

9.     Since the 15 and 17 December 2011 incidents, LTA and SMRT have already been working together to implement measures to enhance the systems reliability and incident management. Both parties will study the findings and recommendations of the COI, with a view to making further improvements.

10.   The Minister for Transport will make a Ministerial Statement at the July Parliament sitting, to give the Governments response to the COI's report.

11.   The full report can be accessed here.

To view Annex A, click here.
To view Annex B, click here.