Lam Tin MTR incidents linked by a safety switch, but causes stay unresolved

Preliminary findings on the Lam Tin MTR incidents show how a safety measure taken after an October 13 trackside fire formed part of the conditions behind smoke at the station the next morning. A failed insulating rubber component caused the first short circuit, according to a joint government and MTR paper. A portable grounding switch then stayed closed for safety, and sustained high current on a worn grounding connection overheated a cable on October 14. The railway has not yet established the complete causes of either incident.

The paper for the Legislative Council’s railways subcommittee, made public Tuesday ahead of its October 30 meeting, offers the fullest account yet of two disruptions roughly 15 hours apart on the Kwun Tong line. MTR has been asked to submit a full investigation report within a month of the incidents. The preliminary findings were also reported by TVB and The Standard.

What the Lam Tin MTR incidents report says

At about 5:30 p.m. on October 13, a train driver spotted track equipment on fire in the tunnel between Lam Tin and Yau Tong, the paper says. MTR temporarily closed Lam Tin Station and stopped Kwun Tong line trains from serving Lam Tin, Yau Tong and Tiu Keng Leng. Firefighters extinguished the fire at about 6:20 p.m.; service began returning to normal at about 6:30 p.m. The Tseung Kwan O line continued to serve Yau Tong and Tiu Keng Leng.

Investigators initially found that an insulating rubber component between parts of a track switch near Lam Tin had failed. That created an unintended electrical path between the train traction return circuit and the station’s grounding system, causing a short circuit, high current, sparks and fire. The paper does not yet say why the rubber failed. MTR and technical experts are testing the component and examining whether its material condition, surroundings or other factors reduced its insulating performance.

To keep current from flowing through the damaged component, engineers closed a portable grounding switch at the site. It stayed closed through the remaining train service that evening, according to the paper. MTR replaced the damaged rubber and associated parts overnight, but the switch remained closed for safety during train service the following morning.

Why the second incident followed

At about 8:30 a.m. on October 14, a smoke detector in an electrical room beside Lam Tin’s Platform 2 activated a suppression system. Smoke spread toward the platform. Staff evacuated the station, and Kwun Tong line trains continued running but did not stop there. The station reopened at about 9:55 a.m. after temporary repairs, tests and safety checks.

The paper says a connection on a grounding busbar in the electrical room showed wear. With the portable grounding switch still closed, sustained high current increased the load on that connection and accelerated the wear. Under a particular heavy-load condition, the connection had limitations: some current took another grounding route instead of its intended path. The continuing current overheated grounding components of a cable and produced smoke. MTR has repaired the connection and replaced damaged cable, but the paper expressly leaves the detailed causes and contributing factors for further investigation.

That distinction matters. The closed switch was a protective response to the first fire, not by itself a completed finding of operator error. The investigation is examining equipment, operating and maintenance procedures, site conditions, power behavior and staffing. MTR says it has commissioned an independent external electrical-engineering expert and asked suppliers to help analyze the faults.

Network checks and what passengers get

MTR says it has inspected all similar insulating rubber components across its operating lines and found no other abnormalities. It plans more frequent inspection and cleaning, and is studying sensors that could detect deterioration continuously. It is also checking stations with portable grounding switches and reviewing their grounding arrangements and operating procedures. Those checks are measures underway, not proof that the underlying problems have been eliminated.

The two disruptions hit busy travel periods. The paper says MTR deployed more than 210 additional frontline staff and arranged about 150 free shuttle-bus trips across the incidents. The arrangements were not smooth for everyone. In an October 14 RTHK report, commuters described difficulty reaching an outdoor shuttle stop by a long staircase and frustration with service information. Those were reported passenger experiences, not findings about every shuttle arrangement.

Both incidents also fall under MTR’s service-performance rebate mechanism, the paper says. The company must contribute money to a pooled account for serious disruptions of at least 31 minutes within its control, with an additional amount because these occurred during peak periods. The paper gives no contribution figure for these incidents and promises no direct refund to individual affected riders. A designated half-fare day is arranged when the account accumulates HK$25 million. The last such day was October 24, as TockHK explained; the paper does not announce the next one.

The full report should establish why the insulation failed, whether the busbar’s condition or grounding configuration needs a wider fix, and which procedures should change. Until then, the strongest conclusion is narrower than a complete root-cause finding: the first fault prompted a protective electrical configuration that exposed a second weak point the next morning.