Imelda Saad Aziz Today Online 22 Jun 10;
SINGAPORE - The National Parks Board or NParks says it has stepped up inspection and pruning of trees across Singapore following the recent spate of intense weather conditions.
A 32-year-old man was killed on Tuesday when a tree fell onto his car during a storm. Residents at Thomson Hills say they've seen their fair share of uprooted trees over the years.
Ms Chloe Chiang said: "There was a tree that fell near my house, just down the road from here, couple of weeks ago during heavy rains. It was kind of lucky because it fell on the pavement, it almost hit a car."
Mr Chua Loong Wai was not as lucky. He was killed after a tree crashed onto his car.
NParks said the tree was healthy. It was uprooted due to a weather condition called a "microburst" - localised strong columns of very-rapidly descending air.
The wind speed at the time of the accident was as high as 65 kilometres per hour.
A day after the accident, workers were seen inspecting trees in the area. Trees lining the road seemed to have been trimmed.
Residents in the area said trees were pruned early this year when drainage works were carried out.
Still, they're hoping for more regular inspections but they also acknowledge that no one could have anticipated the freak accident.
NParks said it has over the past two months, stepped up inspection and pruning of trees, focusing on mature trees and where vehicular traffic is high.
On top of routine operations, 2,000 more large mature trees have been inspected and crown reduction carried out.
NParks director of Streetscape Simon Longman explained: "Crown reduction pruning is this method of bringing in the side branches and reducing the weight of the trees to get a more compact crown."
This way when trees do fall, they hit a smaller surface area and hopefully will do less damage.
Separately at Mr Chua's wake, friends and family members were seen quietly grieving. Mr Chua left behind his wife and his two-and-a-half-year-old daughter.
It's understood that Mr Chua's wife may consult a lawyer to see if any action should be taken against relevant authorities. Imelda Saad
Sudden wind gusts have wreaked havoc before
Amresh Gunasingham Straits Times 22 Jul 10;
THE freak gust of wind that is believed to have brought down a tree that killed a motorist on Tuesday is a regular weather phenomenon in Singapore, experts say.
Called a microburst, it can strike several times a month, especially during wetter ones. As the name suggests, microbursts are short and last for just five to 15 minutes. They can be devastating, however, producing winds of up to 160kmh.
According to the National Parks Board (NParks), one such microburst generated winds of 65kmh in the Upper Thomson area on Tuesday afternoon, and it could have brought down the 30-year-old rain tree that killed Mr Chua Loong Wai, 32, along the junction of Thomson Hills Drive and Yio Chu Kang Road.
A microburst results when a localised and very intense downdraft descends to the ground during a heavy rainstorm.
Professor Lim Hock, founding director of Temasek Laboratories, explained: 'The heavy rain of a severe storm cools a whole column of air and drags it down. The cold air spreads out on hitting ground, creating a local region of very strong wind.'
Experts say other factors, such as hilly terrain and certain building designs, can also contribute to a strengthening of winds during a heavy rainstorm, bringing about a microburst.
The powerful gusts of air have wreaked havoc around the world, and have even been blamed for plane crashes.
Prof Lim said: 'They are a threat to aircraft taking off or landing, and have been found to be responsible for crashes...they are also quite capable of uprooting trees or snapping thick branches.'
In 2007, for example, a powerful wind surge was blamed for causing the crash of a jet belonging to budget airline One-Two-Go in Phuket, killing 90 of the 128 people on board. Many airports around the world are thus equipped with wind shear sensors that can detect microbursts and forewarn pilots.
In Singapore, the phenomenon has been known to wreak havoc on at least two other occasions.
The first was in 2002, when two people were injured and three cars damaged when seven trees were uprooted along the Central Expressway by a powerful microburst.
The other incident occurred in Holland Village in March last year, when six vehicles and some property were damaged by falling trees.
Meteorologists say microbursts can occur several times a month in Singapore because of the tropical monsoonal weather here, which is characterised by thunder and heavy rain.
Such bursts of wind are commonly associated with the north-east monsoon season, which occurs between December and March, and during Sumatra squalls, which can bring up to two hours of thundery showers and are usually accompanied by gusty winds packing speeds of up to 80kmh.
