Friday 24 April 2015

LTA to install more sensors to monitor tremors

By Christopher Tan, Senior Transport Correspondent, The Straits Times, 23 Apr 2015

TREMOR monitoring systems will be installed at 18 transport structures across the island, more than treble the number already monitored by earthquake sensors.

While Singapore has been quake-free so far, the Land Transport Authority (LTA) explained that enhanced surveillance is required because of tremors from nearby quakes.

Observers said that the increase is likely to be tied to recent recognition that the island is not entirely immune to seismic risks.

Two years ago, for instance, the Building and Construction Authority adopted new building codes that include guidelines on making buildings more quake-resistant.

To be better prepared, the LTA has called a tender for contractors to install the tremor monitors at places such as Tuas Second Link, West Coast Highway, Kranji Expressway near Yew Tee Flyover, the Clementi-Jurong East MRT viaduct, Queenstown-Redhill MRT viaduct and Punggol LRT near Riviera station.

It will also replace monitors at five locations where tremor monitors were installed between 2008 and 2011. They are Jurong East MRT, Kallang MRT, the Circle Line's Dakota tunnel, Benjamin Sheares Bridge and Tanah Merah Flyover.

The contractor will also supply new software and a central control system.

An LTA spokesman said that even though Singapore is not in an earthquake zone, tremors from nearby quakes are felt here.

"The expanded coverage will enable engineers to retrieve information required to facilitate planning and deployment of engineers to inspect specific structures quickly if warranted," she said.

Professor Li Bing, director of the Nanyang Technological University's Natural Hazard Research Centre, said that the move is "necessary".

"We seem to be in a very safe zone, but we also have a very short history," he said, explaining that earthquake studies usually span hundreds of years.

"Earthquakes are black swan events," he said, citing recent quakes that devastated cities like Hiroshima, Japan and Christchurch, New Zealand, which were previously not deemed risk-prone.

"I grew up in Christchurch, and nobody talked about earthquake back then," he said.

Assistant Professor Wei Shengji, from NTU's Asian School of the Environment, said that tremor monitoring systems have been in use since the early 20th century, in places such as Los Angeles, Mexico City, Beijing, Rome and almost every city in Japan.

Prof Li, however, said a drawback of monitoring systems is in "what you do with the big data".

"You need specially trained people to analyse the data properly," he said.

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