ONE of the longest underground concourses in Hong Kong opened yesterday, linking one of the territory's largest developments to the Mass Transit Railway. The 110-metre concourse, linking Causeway Bay station with the $2 billion Wharf Properties Limited Times Square retail and office project, opened to the public at 3.30 pm. Construction of the concourse started two years ago as part of the $850-million Causeway Bay underground project which began in the early 1980s. Mass Transit Railway Corporation (MTRC) Operations Director Bill Donald has not ruled out further links. ''It is not necessarily the last one for Causeway Bay. We are always looking for opportunities to make more convenient access to the railway,'' he said. ''This sort of development will be quite regular with the MTR, although they take some building and you won't see more than one a year. ''Times Square is undoubtedly one of the biggest developments along the route of the railway.'' Mr Donald said the MTRC's next major priority would be securing the development of a line to the airport, which would relieve congestion for at least 15 years after completion. More than 160,000 shoppers, tourists and office employees are expected to pass through the new concourse daily. The MTRC link was the second major project for Wharf Holdings Limited this week following the launch of its cable television network on Sunday. Wharf Holdings Executive Director Edward Cheng Wai-sun said it was fitting that the Times Square location, once the site of the old tramways depot, had become ''on track'' with a direct link to the MTR.