1. Another scandal on the SCL—Deceptive construction at Hung Hom Station, platform may crumble at any time

31.05.2018

Fake construction has been uncovered at the Sha Tin to Central Link (SCL) expansion project at Hung Hom Station. According to sources, nearly 20% of the couplers on two of the main platform walls are either damaged or dislodged, meaning they cannot be tightened to the steel structures supporting the weight of the platform. In an effort to hide their failure, construction contractors are suspected to have cut the steel bars shorter, which engineers say will drastically reduce their load bearing capacity, and in the worst case scenario may cause the platform to collapse. MTR has admitted that they discovered shortened steel bars and construction cover-ups in December 2015, but insist that they ensured this was rectified before concrete was poured in. However, according to construction records obtained by Apple Daily, concrete had been poured into some of the defective steel structures as early as September. MTR chairman Frederick Ma, who was criticised for his irreverent attitude in his response to the high speed rail accident, refused to comment when asked about the scandal yesterday.

By Leung Yu-wo

The current construction project aims to expand the underground platform at Hung Hom Station to two levels: the upper level platform for the East-West Corridor (currently the Tuen Ma Line) will connect to the West Rail Line via Ho Man Tin Station, while the lower level platform for the North-South Corridor (currently the East Rail Line) will connect to Exhibition Centre and Admiralty Stations via an underwater tunnel.

Construction plans call for two underground diaphragm walls on either side of Hung Hom Station, each approximately 218 metres long, with a concrete slab more than 5,000 square metres in area lying between the two walls to create the two levels. When constructing the concrete slab, workers will first insert horizontal steel bars into the walls, screw the bars to the walls with roughly 30,000 couplers, and then pour concrete to form a 3-metre thick slab that will bear the weight of the Tuen Ma Line platform and trains.

A subcontractor working on the SCL previously reported the cover-up to Leighton Asia, with photographic evidence dated September 2015 of workers installing shortened steel bars onto walls. Photo: anonymous source.

A worker uses handheld hydraulic shears to cut steel bars short, in order to fake a secure fastening into the couplers.

Water leakage can still be seen on the wall in question even recently. Photo: Apple Daily.

Steel bars shortened and forced into dislodged couplers

According to inside sources, after the two diaphragm walls were completed in mid-2015, roughly 5,000 couplers were either dislodged, damaged, or plugged with concrete, and thus could not be fastened to the steel bars. Leighton Asia, the construction contractor, failed to properly address the problem, instead telling construction workers to cut the ends of the steel bars shorter so that they could be forced into the faulty couplers, thus faking a secure connection. When properly fastened, steel bars should be inserted approximately 10 cm into their couplers, yet some of the shortened bars were inserted less than 1 cm into their couplers. 

Higher-ups at Leighton Asia were well aware of these faults, according to multiple emails obtained by Apple Daily. A January 2017 email to Leighton Asia, sent by Chinat Engineering, the subcontractor in charge of the concrete slab, noted that as early as September 2015 Chinat discovered faulty couplers in the walls, as well as workers wearing Leighton uniforms taking advantage of MTR supervisor shift changes to cut steel bars short and fake a secure connection. Attached to the email were photos taken in September 2015, showing workers with portable hydraulic shears cutting and installing steel bars.

A day later, Leighton management responded in an email, saying that they were now looking into the issue and rebuking Chinat for not reporting the issue earlier. Chinat replied that according to their own internal investigation, Leighton managers on site had long known about the issue and had even instructed workers to cover up the mistake.

Councillor alleges fraud, demands investigation

According to civil and structural engineer So Yiu-kwan, cutting the steel bars short to force a connection is “an act of deception” that can impact the structure’s load bearing capacity: “The entire floor could simply crash down… If anything happens, it will happen so suddenly that no-one will have time to react.”

In a statement issued two evenings earlier, MTR said that deficiencies were discovered during inspection in December 2015, and remedial measures have been completed after the subcontractor received a stern warning; furthermore, the incident bore no impact on the structural integrity of the tunnel, construction timetable, or construction costs. When questioned about the issue yesterday, Transport and Housing Secretary Frank Chan also claimed that it had been fixed before concrete was poured in. Yesterday at noon, when a reporter asked, “Were steel bars shortened to look as if they were securely fastened?”, MTR officials publicly admitted, “We did discover this occurred,” publicly admitting for the first time that such deceptive acts happened, and that the contractor was ordered to remove the defective steel bars.

Civic Party Legislative Councillor Tanya Chan expressed her shock, demanding that law enforcement authorities should investigate whether fraud was committed. She also wanted MTR and the Transport and Housing Bureau to clarify how they will rectify the issue and to have an independent committee investigate the SCL expansion project.

2. [Exclusive] At To Kwa Wan Station, suspected broken steel bars in structural walls may drastically reduce load-bearing capacity

11.06.2018

By Cheng Kai-yuen

Faulty construction has been discovered at the To Kwa Wan Station on the Sha Tin to Central Link. Sources say construction workers have used gas welding torches to cut short steel bars in the station’s structural walls, which is a violation of construction regulations. According to senior welding workers, since heat impacts the tensile strength of steel bars, industry professionals rarely use welding torches to cut steel bars, and will need to reinforce the structure with additional steel bars if they do to maintain the load bearing capacity of the wall. However, sources say that the contractor ordered concrete to be poured in before any reinforcement was done, to cover up their defective construction.

According to Wong Wai-man, a senior iron and welding worker and a council member of the Bar Bending Industry Workers Solidarity Union, walls with double layers of steel bars usually serve a structural, load-bearing function: “Changing the design from double layers to a single layer can be done, but other measures must be taken to reinforce the strength. At the very least, there must be additional anchor points to help secure the bars to the wall, to preserve its structural strength.” Additionally, he adds, the usual method on construction sites is to use hydraulic shears or cutting machines to cut the bars, instead of welding torches: “Workers will certainly have been taught, heating a steel bar with a torch will reduce the tensile strength of the area within 1 metre from where the flame was applied, and additional bars must be added to maintain the strength of the wall.” Pouring concrete without reinforcing structure will cause safety issues.

Wong Wai-man adds that such shoddy practices are hard to discover and scrutinise once concrete has been poured in. However, inspectors can still use rebound hammers or ultrasound devices to test if the strength of the walls are still up to standards.

Sources say that MTR is awaiting a detailed final report and recommendations for remedial measures, which may involve entirely rebuilding the affected walls in the worst case scenario. Although the contract between MTR and the contractor has a liability clause, the only legal measure MTR can take is to require the contractor to “revert to” the original design. The contractor must also compensate MTR for construction delays caused by their negligence. If the line’s opening date must be delayed, MTR can also request compensation for lost ticket revenue, although this is capped at a certain amount.

3. [Exclusive] SCL Scandal: At Exhibition Centre Station, wrong drawings led to wrong walls

19.06.2018

In a report submitted today to the government regarding support frames at the Exhibition Centre Station on the Sha Tin to Central Link, MTR claims that construction was conducted under its rigorous supervision. Yet according to internal documents obtained by Apple Daily, miscommunication at the Exhibition Centre Station resulted in errors in the design drawings, leading to two diaphragm walls being installed in reverse. Both the contractor and MTR were completely oblivious and approved concrete pouring, only realising the issue after installation was finished. Engineers say that such a serious error will impact the load bearing capacity of the diaphragm walls, while legislative councillors have criticised MTR for its negligence.

By Leung Yu-wo

To construct the underground platforms and tunnel at Exhibition Centre Station, workers first dug trenches along the two sides, then inserted “cages” made from steel bars into the trenches, after which concrete was poured in to form diaphragm walls. Finally, dirt between the diaphragm walls was dug away to create room for the platform interiors and floors. 

Apple Daily obtained a non-conformance report issued by MTR to its contractor, Leighton-China State Joint Venture, as well as a quality alert issued internally by Leighton, both of which showed serious errors during the construction of the diaphragm walls.

According to the reports, the subcontractor mistakenly reversed the steel cages during installation, so that the main rebar that should be facing inwards toward the station were instead facing outward. Construction drawings show that the two diaphragm walls, designated L108 and L109, should be connected to each other, for a total length of roughly 12 metres. The two walls are located underneath the Hong Kong Convention and Exhibition Centre, inside what will become the Exhibition Centre Station.

The reports note that the error was caused because the main architect labelled the two sides of the diaphragm walls as “trench side” and “dirt side”, yet one of the other architects labelled the two sides as “north side” and “south side”. The subcontractor then misinterpreted the directions during construction, yet neither on-site workers nor inspectors realised the mistake, only discovering the error after concrete had been poured in and the walls were finished.

According to the reports, the contractor did not redo the two walls in question, but instead installed buttress panels on the side for reinforcement. The reports further mention that the Buildings Department had approved this remedial measure, but new drawings had to be submitted for approval. 

In Leighton’s internal quality alert, the “lessons learnt” section noted the need to review internal procedures and resources, and it required employees to be on the alert for and report anything unusual or incorrect.

According to civil and structural engineer So Yiu-kwan, construction mistakes this serious very rarely happen. He explains that underground diaphragm walls need to withstand the pressure from the soil above; the deeper the walls are in the ground, the more pressure it must withstand. Since the side facing toward the station is under greater pressure, this side of the wall needs to be reinforced with more hefty steel bars than the exterior-facing side: “If the wall is installed in reverse, so that one side has too much steel, and the other side does not have enough steel, the structure might collapse in the worst case scenario.”

So Yiu-kwan further doubts whether the contractor and MTR followed proper procedures during inspection: “A mistake this serious would have been easy to discover, since the steel bars on one side are very obviously thicker than the other. If someone really did check, how could they have not seen it?” He adds, if the pressure from the soil above is not too severe, walls inside the station can be reinforced to withstand the weight, but the authorities must be notified since this requires alterations to the original design.

In the past few days, MTR has repeatedly stressed that all construction work is conducted under supervision, and concrete pouring must be signed and approved beforehand by both the contractor and MTR inspectors. However, now that another instance of concrete pouring before a mistake was discovered has come to light, Legislative Councillor Tanya Chan has criticised MTR for its negligence and demanded that MTR reveal how many quality alerts have been issued for this project–as well as the criteria for issuing such alerts. Apple Daily has approached MTR, the Highways Department, and Leighton for comment, but has yet to receive any response.

Diaphragm walls at Exhibition Centre Station were mistakenly installed in reverse, but only post-installation remedial measures can be undertaken, since MTR approved concrete pouring before the mistake was discovered. Photo: Ha Ga-long

Correct installation: Main rebars should face toward the station, so that the steel cage can withstand pressure from the soil outside.
Incorrect installation: The contractor installed the steel cage with the main rebars facing externally toward the soil, resulting in thinner rebars on the station side. This may cause diaphragm walls to tilt toward the station, if the thinner rebars on the station side are unable to withstand the combined pressure of the soil outside and the weight of the now external-facing thicker rebars.

Internal documents obtained by Apple Daily showed that two diaphragm walls at Exhibition Centre Station were installed in reverse.

Leighton issued a quality alert in June 2016 detailing the incident.

MTR issued a nonconformance report to Leighton in June 2016 requiring a remedial proposal.

If correctly installed, both the red couplers and the thicker main rebars should face the excavation side, but Leighton’s quality alert clearly shows that the steel cage was installed in reverse: thicker steel bars are in the rear, with couplers fastened on thinner rebars.

The diaphragm walls in question were installed just outside the Hong Kong Convention and Exhibition Centre and the Renaissance Harbour View Hotel. Construction is currently ongoing at what will become part of the Exhibition Centre Station.