Why bearing pads are unsung heroes of metro systems
Buet's Prof Md Shamsul Hoque says the primary roles of bearing pads are to evenly distribute the immense weight of passing trains, absorb vibrations, and accommodate natural movements caused by temperature changes and traffic.
Bearing pads are the unsung heroes of any elevated rail or road network, like metro rails, according to Prof Md Shamsul Hoque, director of Buet's Accident Research Institute.
Made of an elastomeric rubber-steel composite, they sit between the concrete deck (the bridge that carries the trains) and the supporting piers, Shamsul, also former director of DMTCL, which operates the Dhaka metro rail, wrote in an analytical piece published by The Business Standard today (27 October).
His comments come after yesterday's tragedy, where a dislodged bearing pad fell from the metro rail structure and killed a pedestrian, which has once again highlighted the need for rigorous inspection and maintenance of these crucial components.
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The expert said the primary roles of bearing pads are to evenly distribute the immense weight of passing trains, absorb vibrations, and accommodate natural movements caused by temperature changes and traffic.
"When they fail – through hardening, extrusion, misalignment or, as in this case, a complete dislocation or "fall down" – the results are catastrophic. The load distribution becomes uneven, creating dangerous stress concentrations that can misalign the deck and damage the piers themselves," he added.
Yesterday, at around 12:20pm, a load-bearing pad on pillar 433 near the Farmgate metro station detached and fell, resulting in one death and injuries to two others, also disrupting services for hours.
Just a year ago, on 18 September 2024, a bearing pad on pillar 430 near the same station fell from the metro structure. Although no casualties occurred then, services were suspended for nearly 11 hours.
