A TBM severely damaged by floodwater is affecting progress on the Hong Kong Section of the Express Rail Link (XRL) project. This unforeseen challenge has added to the difficulties of the project and will push the completion date to 2016 with the line ready for operation in 2017.
“The Express Rail Link project is a very large undertaking and immensely complex. Since construction began, we have been presented with numerous challenges which have put pressure on our schedule,” said Mr T C Chew, Projects Director of MTR Corporation. “We have been very focused on catching up through fine-tuning designs and adjusting the construction works but this latest situation with the TBM makes it clear that completion of the project by 2015 is not achievable.”
During the black rainstorm on 30 March 2014, a section of tunnel in Yuen Long connecting Tsat Sing Kong and Tai Kong Po was flooded when heavy rain washed soil and debris into the work site, blocking the surface drains. As a result, flood water found their way into the partially bored tunnel where the TBM was located.
After clearing the site, the MTR project team, the contractor and TBM manufacturer conducted detailed inspection of the TBM to assess the extent of the damage. Their findings have concluded that substantial repair work is required, particularly complete replacement of the sophisticated electronic components, before the TBM can become functional again. Further studies are being carried out to determine whether the TBM should be repaired or if an alternative method should be used to finish excavating the remaining tunnel section. The current assessment is a prolonged delay of up to nine months in the construction programme.
There are two other critical locations where the challenges are of particular concern. One is the extremely difficult ground condition at the West Kowloon Terminus site. The underground rock strata sitting at a higher than expected level is requiring more time to excavate. But progress has also been hindered by boulders and uncharted utilities that had to be negotiated during the excavation process.
The second critical challenge involves the complex geology at the cross-boundary section of the tunnels under the protected wetland area. As marble caverns are known to be located in the zone, tunnel boring work have to proceed with extreme care and any unforeseen circumstances will have to be dealt with as they surface.
“As you can appreciate, the unforeseen challenges of this project are great. Difficult ground conditions, unforeseen obstructions and the black rainstorm have all impacted our programme. While we make every effort to complete the XRL project as early as possible, we will strictly uphold our ‘safety first’ principle in the management of our worksites and the safety of our workers,” added Mr Chew.
“Taking all this into account, we needed to set out a new timeline for the completion of the project, with major construction works to be finished within 2016. With the time required for testing and commissioning to ensure safe operations, the opening of the line for passenger service will be in 2017. We recognise the Government has entrusted the management of this project to us and we are sorry to have to bring forth this revised schedule. Nevertheless, this will now allow us to complete this project and deliver an important addition to Hong Kong’s transportation network.”