Complaints about construction noise and poor ground conditions have been blamed for a slowdown in work on the MTR's Kwun Tong line extension, which risks missing its target completion date of the middle of next year. In a report presented for a committee meeting at Kowloon City District Council yesterday, the MTR Corporation said excavation to build a tunnel linking two concourses of the future Whampoa station had fallen behind schedule. About 70 per cent of the work should have been done by the end of April, but only 54 per cent was completed. A major reason was restrictions on the time of day work could be done due to complaints about noise from nearby residents. The contractor had obtained a round-the-clock work permit from the Environmental Protection Department valid for two months from mid-January to mid-March, but after the complaints, the MTR shortened work time to 16 hours a day - between 7am and 11pm - from mid-February onwards, "for the good of the community". "Variable ground conditions" presented another challenge for engineers, the report said. "Currently, the project is still targeted for completion by mid-2016. The construction team is making every possible effort to speed up the work," a spokeswoman for the MTR said. Council member Pius Yum Kwok-tung said residents would be hoping the new stations will be in service as soon as possible. "It will shorten commuting time from Whampoa to Mong Kok from half an hour at peak time to less than 15 minutes," he said. Whether work should be done overnight should depend on the level of inconvenience experienced by residents, he said. Separately, former Highways Department director Wai Chi-sing insisted yesterday it had been reasonable to estimate the new high-speed rail line to Guangzhou would be finished in five years as originally planned. Work on the multibillion-dollar link began in 2010 and was supposed to end this August, but completion has been pushed back two years to at least the end of 2017. Wai told a Legislative Council panel no contractor had raised concerns the target would be unachievable or over budget. "I felt the date was grounded and reasonable," Wai said.