A 12-storey-high tree that crashed through five apartments at Pearl Bank Apartments in Outram on Sept 11 had been flagged as a risk by its management council more than a year ago.
Residents had been worried that the tree, a Purple Millettia over 60 years old, would collapse onto the building, management council chairman Cecilia Seet told The Straits Times. "We warned NParks (National Parks Board) and gave them feedback last August that the tree in particular was very tall. It stood on a slope and there are strong winds in the area... so we were very concerned for the safety of our residents," she said.
While no one was hurt, some apartments suffered damage. Windows were shattered, window grilles fell off their hinges and bathroom fittings were broken.
Ms Seet said she is concerned that the other towering trees that dot Pearl's Hill City Park pose a danger to park users and residents.
In response to queries, NParks said the Purple Millettia tree was last inspected in February by its arborists, who found it healthy and observed no visible signs of damage or disease. A month earlier, the tree had been pruned to lighten the weight of the crown.
It noted reports of strong winds of at least 50kmh and rain during the weekend of Sept 10-11 which it said probably weakened the tree.
After the incident, NParks cleared the fallen tree, which had been standing in the adjacent Pearl's Hill City Park even before the apartment block was completed in 1976. NParks also checked the trees around Pearl Bank Apartments last Tuesday and found them to be healthy.
The annual number of fallen branches and trees under NParks' management has dropped from over 2,500 before 2004 to about 1,300 per year for the past decade or so.
A Pearl Bank resident who gave her name as Madam Seow, 48, said parts of the bedrooms in her apartment and the living room were damaged by the tree. But the accountant said she was relieved that her family was not hurt.
She added that she will miss the shade that the tree provided.
NParks said it is in contact with residents whose windows were damaged during the early morning incident. The apartment building was certified structurally sound by its engineers.
The tree that crashed was one of only two heritage Purple Millettia trees in Singapore. NParks said the other tree in the Singapore Botanic Gardens was last inspected in January and assessed to be healthy. Other Purple Millettia trees grow along roadsides and in parks and gardens.
More than 250 trees are endorsed under NParks' heritage tree scheme. The trees are evaluated based on criteria such as their rarity, size, health and social, cultural or historical significance.
NParks said all trees are inspected using the visual tree assessment technique. Its staff look out for abnormalities such as damage to the trunk, wood-decaying fungi and hanging or broken branches, among other things. If abnormalities are detected and a tree is suspected to have internal defects, staff will conduct a second level of inspections with equipment such as a sonic tomograph or resistograph to detect internal decay.
All trees are inspected every six to 24 months under NParks' tree management programme. Where necessary, crown reduction pruning is done to reduce the weight of tree crowns so that they can better withstand strong winds.
NParks group director of parks Chuah Hock Seong said it is not possible to eliminate the risk of tree falls as trees are living organisms and even healthy ones can be affected by gusty winds and heavy rain.
He said: "We also continuously refine our tree management programme in response to unpredictable weather conditions."