The judge hearing the inquiry into the two major MRT breakdowns last year has asked the government and transport operator SMRT to look into improving ways to detect equipment problems and manage crowds.
Chief District Judge Tan Siong Thye gave his feedback after the lawyers for the Attorney-General’s Chambers (AGC), the Land Transport Authority (LTA) and SMRT made their opening statements on Monday, the first day of the Committee of Inquiry’s hearing into the disruptions on the North-South Line that affected over 220,000 commuters in December.
During the hearing, LTA and SMRT appeared to differ on some of the factors that played part in the disruptions, but the two established that the immediate cause of the disruptions was a power failure after damaged and missing current collector shoes were dislodged from the third rail power system.
Tan said there need to be gauges that provide information to both a train’s driver and SMRT’s Operations Control Centre should a current collector shoe or rail claw be missing or damaged.
He compared this with how the fuel gauge in a car tells a driver when he needs to go for a top-up when the car is running low on petrol. He also pointed out that the opaque covering for the Third Rail should instead be transparent, so that it would be visible to people conducting maintenance checks.
Turning to incident management, the judge said implementing bus bridging services alone during disruptions is not enough to manage the massive amount of passengers that need to be carried during rush hour. He called on all three parties to look into more solutions to better handle the crowd.
Noting that a bus has a capacity of 80 passengers, as compared to an 1,400 for an MRT train, Tan said that more options for travel would invariably be needed for commuters affected by train disruptions.
Tan also questioned whether the length of time that batteries of a train’s emergency power supply was expected to last (45 minutes) is adequate. For three carriages on one of the trains that stalled on the night of 15 December, the emergency power supply batteries did not last.
Opening statements suggest possible causes
On the deeper causes of the disruptions, the AGC, the LTA and SMRT cited expert reports and the results of internal investigations, where applicable, that were submitted to them.
Speaking for the AGC was second solicitor-general Lionel Yee, who also summarised the findings of the separate investigations conducted by SMRT and the LTA.
Based on separate reports submitted by nine science and engineering experts, Yee said the possible causes for the incidents include a cracked fastener, one of the parts that held the Third Rail up. The fastener could have cracked because of impurities in its manufactured material.
Yee also said the disruptions could have been due to excessive vibrations that resulted in the dislodgement of the claws holding up the Third Rail. The vibrations in turn could have been due to several other factors, including flat patches on the wheels of the trains impacting smoothness of travel.
Lawyers from Allen & Gledhill, led by senior counsel Andrew Yeo, conveyed the position of LTA, which is responsible for the acquisition of new trains and owns the MRT infrastructure. LTA also cited excessive vibrations from flat patches on train wheels as a cause for the disruptions, and said these wheels are supposed to be milled by the operator regularly.
Yeo said the LTA found that SMRT’s maintenance regime is “generally comprehensive and satisfactory” but that certain areas require improvement or further review, including the inspection of the Third Rail claws at certain stretches of tracks, the detection of wear in parts of the Third Rail system, as well as the maintenance of train wheels.
A team of lawyers from Drew & Napier, led by senior counsel Cavinder Bull, represented SMRT. Bull said that while the immediate cause of the train disruptions was undisputedly the dislodgement of the rail claws holding up the Third Rail, he contended that the incidents occurred as a result of “a rare confluence of factors”, none of which individually could have caused them.
Citing the reasons offered by experts in the AGC’s opening statement, Bull highlighted the material used to make the fasteners in the claws on the North South Line as a possible key reason for its failure to hold up the Third Rail as it was supposed to.
He pointed out that the claws used on the North South Line were first- and second-generation ones, that were over the years followed up with three newer versions. The third to fifth-generation claws are now used in newer lines such as the Woodlands extension to the North South Line, as well as the Circle Line.
Makers of the Third Rail system used on the North South Line, Brecknell Willis, proposed a modified claw in 1987 to replace the first-generation claw, which relies on the weight of the Third Rail to hold it in place. The modified claw then had a split-pin locking system which ensured that the claw would stay in place, even under severe vibration.
Brecknell Willis’s proposal to replace the claw in 1987 was rejected by MRTC, LTA’s predecessor, however, as they wanted to stick to the older claw designs, said Bull. Noting the importance of this development, Judge Tan instructed the LTA to find out the MRTC’s reasons for rejecting the proposal.
Responding to the LTA’s position with regard to maintenance, Bull said SMRT ensures its maintenance regime is equal to or better than the recommendations stipulated by the manufacturers of the various parts of the system.
He added that wheel flats are “a general issue faced by all rail operators” that did not result from poor maintenance regimes, although made mention to the fact that SMRT is striving to be more preventive than corrective in its wheel profiling processes.
Incident management plan ‘intended for simpler incidents’
Turning to its management of the disruptions that happened on Thursday night, in particular, SMRT acknowledged the weaknesses of its existing management plan at the time, even though the transport operator did follow the planned procedures adequately.
Bull said the categorisation of severity levels in the existing plan pitched the incident on 15 December at Red-2, the second-highest tier, which involves an event that disrupts train service by up to one hour but does not involve casualties or fatalities. The lack of fatalities in the incident, said Bull, prevented SMRT from being able to seek help from external agencies such as the Police and the Singapore Civil Defence Force initially.
SMRT has since reviewed and reclassified its management plan alert tier levels in order to permit greater coordination with external agencies in the event of similar large-scale disruptions, added Bull. He also acknowledged SMRT’s independent review report, which said that SMRT’s bus bridging plan is simply unable to handle train disruptions of the scale experienced on 15 December.
Touching on detrainment, Bull also noted that SMRT’s investigation team opined in its report that detrainment cannot be viewed as a last resort anymore, and whether or not passengers are instructed to walk to the nearest station through a tunnel on foot or “pushed” by another train to a train station should hinge on the time they have spent inside the stalled train, instead of any other factors.
He also added that the rapid increase in train ridership, in particular over the last two years, and the age of the North South Line (25 years) as well as its infrastructure, have contributed to the need for more frequent maintenance work.
Monday’s opening statements were followed by the first witness, Criminal Investigation Department lead officer Roy Lim, who testified that the CID has ruled out sabotage as a possible cause of both disruptions.
Some 108 people will testify in the COI hearing, including the 11 train drivers directly involved in the disruptions, the staff working in the Operations Control Centre on both days, station management staff, three affected commuters — including the woman who fainted on one of the stalled trains — SMRT and LTA senior management staff, including former SMRT CEO Saw Phaik Hwa, and 11 experts who will share their expertise and findings based on the evidence presented.