Unexplained HCMC metro line cracks raise serious concerns

One of the Elastomeric Laminated Bearings pads, which are made from high purity elastomers that encapsulate layered internal steel reinforcing plates and are designed for use in bridge and building constructions as a beam support, fell out from its position between two beams of HCMC’s metro line No.1 in late October.

Until now, the consortium comprising Vietnam’s Civil Engineering Construction Corporation No. 6 (Cienco 6) and Japan's Sumitomo Corporation, the contractor of the line that runs 19.7 km from Ben Thanh Market in District 1 to Suoi Tien theme park in District 9, has failed to make any official statement on why it happened, according to the HCMC Management Authority for Urban Railways (MAUR).

The two beams at a section of HCMC's Metro Line No.1 in Thu Duc District are seen askew after an Elastomeric Laminated Bearings pad fell off in October 2020. Photo by VnExpress/Trinh Quan.

The lack of explanation has prevented MAUR, the project’s main investor, to prepare a report on the incident for submission to higher authorities.

What the contractor has said so far "is not convincing," and paves the way for the contractor to "disclaim responsibility," MAUR said.

The investor has demanded that the contractor submits soon evidence of its own investigation and submit an official report on the issue no later than Thursday.

The project’s consulting unit, NJPT, a consortium led by Japan’s Nippon Koei, has also been requested to do the same.

The railway management authority has found that after the pad between the two beams of the metro line’s elevated section in Thu Duc District fell off, cracks have appeared on the beam and the rail has lost its connection with the supporting system below.

'Could be serious'

Nguyen Van Duc, an expert on road and bridge construction, said there could be many reasons leading to the fall of an Elastomeric Laminated Bearings pad during construction. To find out the real reason, a thorough review is needed, from the very first steps of designing to the construction process and the quality of the pad itself.

One of the reasons that could lead to the situation is the expansion of concrete, which causes a separation between the abutment and the beam, causing the pad to drop, Duc told Dat Viet newspaper of Vietnam Union of Science and Technology Associations.

If this is the reason, then the "incident could be serious and it requires comprehensive inspection of the entire project," Duc said.

It is crucial to find the actual cause of the problem instead of just putting the pad back and continuing the work because that could make the pad drop again, threatening safety of the entire project, he added.

The first metro line of HCMC has already been delayed several times it is unavoidable that this incident will put it even more behind schedule.

He said that the MAUR, as the main investor, could certainly use contractual obligations and payment suspension to force the contractor to find the exact cause of the problem, identify solutions and commit anew to ensure quality.

Cracks appear on one of the beams on a section of HCMC's Metro Line No.1 in Thu Duc District, October 2020. Photo by VnExpress/Trinh Quan.

Soon after the cracks were seen, the contractor said it had fixed the issue, but made no mention of how it had occurred or how it would affect the life of the project.

Shigeki Ihara, project manager for the Sumitomo Corporation, said last month that the incident was just a "single case" on one beam.

However, the State Council for Pre-Acceptance Test of Construction Works has requested MAUR to review the entire area where it happened, inspect nearby areas and make an assessment on how it would affect the safety and average lifespan of the project.

The metro route No.1 will have 14 stations – 11 on elevated sections and three underground.

Its construction is expected to cost VND43.7 trillion ($1.89 billion).

Work on the much-delayed project, which began in August 2012, is more than 78 percent complete now.

The city hopes to complete 85 percent this year and begin commercial operations by the end of next year.

In all, HCMC plans to build eight metro lines running a total of 220 km.