Oral Answer by Ministry of National Development on NParks’ current tree inspection regime

Mar 3, 2021

Ms Hany Soh: To ask the Minister for National Development (a) how frequently does NParks check its trees to ensure that they are in a healthy condition and not prone to falls; and (b) whether there is a safety check regime in place for parks under the charge of NParks to ensure that our parks remain safe for users.

Mr Shawn Huang Wei Zhong: To ask the Minister for National Development (a) what is the current inspection routine and procedure to ensure that trees in public areas are safe from tree rot, infestation and tree failure that can potentially cause a loss of life; (b) whether there are sufficient resources allocated to conduct these inspections; and (c) what are the scenarios that will cause a healthy tree to fail within nine months after its inspection.

Answer:

Ms Hany Soh and Mr Shawn Huang have raised questions about NParks’ current tree inspection regime. I will address Members’ questions together.

NParks has a rigorous tree inspection and maintenance regime that is aligned with the Best Management Practices of the International Society of Arboriculture (ISA). Regular tree inspections are carried out by trained inspectors every six to 24 months, depending on the location and size of the tree. Trees that are close to areas with high pedestrian or traffic activity are inspected more frequently. 

During a tree inspection, NParks’ inspectors conduct a comprehensive visual examination of the tree crown, branches, trunk and roots to assess the tree’s health and stability. Trees that are found to have possible defects are subject to an additional in-depth inspection, which involves the use of diagnostic equipment to assess the internal condition of the tree. Since November 2016, such in-depth inspections are also conducted annually for trees of more than four metres in girth. This is a precautionary measure in response to changing weather conditions, and is over and above the Best Management Practices of the ISA. 

Beyond inspections, NParks has put in place other measures to reduce the risk of tree failure. First, NParks carries out targeted arboriculture treatments to improve general tree health and their ability to withstand severe weather conditions. It prunes trees regularly to remove weak, dry or overgrown branches, and to improve their structure and balance. Second, NParks is also progressively replacing storm-vulnerable tree species with hardier species. Third, NParks uses technology to analyse risks and improve inspection processes. For instance, NParks is piloting modelling techniques to understand the impact of adverse environmental conditions, such as strong winds, on the structural integrity of trees. This will help NParks to better determine the pruning required to improve tree stability. 

To ensure that there is sufficient expertise to perform tree inspections, NParks has built up a pool of certified arborists in Singapore by offering professional training courses and seminars. These courses are conducted by both international and local arboriculture experts, for NParks staff, as well as tree care professionals in the private sector and other public agencies that manage trees. There are currently more than 620 arborists in Singapore who are accredited with the ISA. Apart from its in-house arborists, NParks also requires its tree maintenance contractors to have certified arborists in their teams. 

With this comprehensive tree management programme, NParks has reduced the number of tree failure incidents by almost nine-fold, from 3,100 in 2000 to 339 in 2020. However, it is not possible to completely prevent tree-related incidents because trees are living organisms that can be affected by pests and diseases, as well as environmental conditions. Even healthy and structurally-sound trees can fail during storm events due to exceptionally strong winds or heavy rainfall. 

Lastly, Ms Hany Soh has asked about whether NParks has a safety check regime in place for its parks. Beyond trees, safety inspections are also carried out for park infrastructure and facilities. NParks appoints registered professional structural engineers to inspect the structural integrity of buildings and structures in its parks, such as shelters, bridges and monuments, once every five years, in accordance with statutory requirements under the Building Control Act. Regular and systematic checks of park facilities are also conducted by NParks staff and external inspectors. For example, all playgrounds are inspected monthly by NParks staff, and every six months by external Certified Playground Safety Inspectors. This allows NParks to detect and rectify defects in a timely manner, and to keep our parks safe for users.

In conclusion sir, the questions raised by Members are in relation, if I assume rightly, to the recent Marsiling Park death. We deeply regret the loss of life. Every one death or injury as a result of tree fall incidents is one too many. My colleagues at NParks and the arborist community work hard day after day to keep our streetscape, parks, and nature areas safe for Singaporeans to enjoy. We will continue to press on, keep up the work, and ensure that our City in Nature is safe and enjoyable for everyone.