Mitigating Waterfall Effect Due to Roof Structures on Sheltered Walkways outside Buildings

Mr Chong Kee Hiong asked the Minister for National Development regarding the roof structures on sheltered walkways outside buildings, whether the Ministry will consider redesigning these structures to mitigate the waterfall effect created on both sides during heavy rain and strong winds.

Sheltered walkways are intended to provide cover against elements, such as sun and rain, while allowing natural light and ventilation. The design of such walkways takes into consideration both functionality and ease of maintenance.

For example, in Housing and Development Board (HDB) developments, the design of the sheltered walkways takes into consideration the effective width to height ratio of the walkways, and whether there are sufficient roof overhangs, appropriate roof slopes and proper alignment of the roof eave to drains. Through effective design, users are adequately protected from the weather.

To minimise the need for maintenance, HDB's sheltered walkways are designed to be self-cleansing and for rainwater to drain off directly from the roof wherever possible. The design avoids the use of roof gutters which would trap leaves and other debris, thus requiring regular cleaning and maintenance to avoid any blockage and water stagnation that could lead to mosquito breeding.

In recent years, sheltered walkways built by HDB and the Land Transport Authority also have roof designs such that they are sloped to one side, so that discharge of water during heavy rain only occurs on the side where pedestrians are less expected to cross. The relevant agencies will take in the Member's feedback and will continue to study how the design of our infrastructure can be improved.