Detached metro rail bearing pads had defects: Probe committee

An investigation committee has found that both bearing pads that became detached from a Metro Rail pillar in the capital’s Farmgate area were defective.

The findings were disclosed at a briefing held on Thursday at the conference room of the Road Transport and Highways Division at the Secretariat.

Adviser to the ministries of Power, Energy and Mineral Resources, Road Transport and Bridges, and Railways, Muhammad Fouzul Kabir Khan, was present at the briefing.

The committee said that among 8 to 10 parameters examined for the two detached bearing pads, two parameters did not meet acceptable or expected standards.

However, the committee clarified that this does not allow a definitive conclusion that all bearing pads are either faulty or sound.

The probe committee also reported that no evidence of sabotage was found in connection with the incident.

Muhammad Fouzul Kabir Khan said that on 26 October, a bearing pad became dislodged and fell from a Metro Rail pillar in the Farmgate area, killing a pedestrian.

The victim was identified as Abul Kalam, a resident of Shariatpur.

Following the incident, an investigation committee was formed on the same day under the leadership of Bridge Division Secretary Mohammad Abdur Rauf.

He said the five-member committee included Professor ABM Toufik Hasan of the Mechanical Engineering Department at Bangladesh University of Engineering and Technology (BUET), Associate Professor Lt Col Md Zahidul Islam of the Civil Engineering Department at MIST, and Brig Gen (retd) Mohammad Abdul Wahab, project director of MRT Line-5 at DMTCL.

Deputy Secretary Asfia Sultana served as the member secretary. Later, the chief engineer of the Local Government Engineering Department was added to the committee.

In addition, the committee co-opted two expert members: BUET professors Khan Mahmud Amanat and Rakib Ahsan.

To properly investigate any possible acts of sabotage, CID official Muhammad Touhidul Islam was included in the committee as a forensic representative.

The adviser said the committee began work immediately after being assigned. Members visited the accident site and interviewed eyewitnesses, the train driver and operator, metro rail officials, and other concerned individuals. The committee also interviewed the bearing pad manufacturer, contractors, and design consultants.

Design documents, relevant data, and reports were thoroughly reviewed. The committee inspected various parts of the metro rail structure and conducted critical tests, including laboratory testing of the dislodged bearing pads and vibration measurements during train operations.

After holding ten meetings and analysing all collected information, the committee finalised its investigation report.

According to the adviser, preliminary findings indicate that the hardness, compression set, and neoprene content of the dislodged bearing pads did not comply with prevailing standards.

However, further testing in overseas laboratories is required to confirm these findings.

He also noted that the bearing pads were installed with a slight slope of 0.8%, which is believed to have contributed to their dislodgement.

The adviser said the Farmgate metro rail station has circular alignment at both ends. It was observed that no transition curve was used between the straight and curved sections of the viaduct alignment.

The committee found that there may be design flaws in the metro rail alignment, as separate modelling and analysis were not conducted for the curved alignment. Instead, the design for the curved section was prepared based on modelling and analysis of the straight alignment.

Vibration measurements taken during train operations showed significantly higher vibrations at the piers associated with the dislodged bearing pads—Pier No- 430 and Pier No- 433—compared to other piers.

The committee believes that possible design flaws in the curved alignment caused undue lateral forces and associated vibrations, which are linked to the dislodgement of the bearing pads.