Flood Management and Adaptation Measures for Public Transport Systems

Mr Leon Perera asked the Minister for Transport (a) what are the flood adaptation plans for Singapore’s transport infrastructure; (b) what improvement efforts are planned to prevent episodes of flooding on major roads; (c) whether the Ministry has conducted studies examining the impact of intense rainfall events on commuter behaviour and how it affects our public transport targets; and (d) whether a standardised climate change impact assessment approach is used for transport infrastructure and, if so, what is the approach.

All existing transport infrastructure are required to conform to minimum platform and crest levels stipulated under PUB’s Code of Practice (COP) on Surface Water Drainage, which sets out drainage and flood protection requirements for all developments. The COP is reviewed regularly to ensure that the drainage system remains robust in light of urbanisation and changing weather patterns.

To address the impact of climate change, PUB raised drainage design standards in 2011, which required an increase in drain capacities by up to 50% to cater for more intense rainfall events. LTA has ensured that all rail, road tunnels and bus infrastructure meet the enhanced flood protection requirements to mitigate flood risks. These include designing the platform level for bus interchanges and depots to be 0.6 metres above the adjacent road, and the minimum crest level for underground MRT stations to be 1.3 metres above adjacent road or ground level. Similarly, the entrances to all developments which are linked to underground MRT stations are required to be built at least 1.3 metres above the adjacent road or ground level.

For stations built before 2011 where crest levels do not meet the latest requirement, LTA has enhanced the flood protection of these stations by putting in place mitigation measures, such as flood barriers, to reduce the flood risk. These flood barriers are inspected on an annual basis to ensure their structural integrity. LTA will continue to work together with agencies and rail operators to review flood protection measures to ensure that they remain effective amidst increasing weather uncertainties.

As climate change will bring about more frequent and intense storms, LTA and PUB are currently reviewing the flood risk of MRT stations and depots. The preliminary assessment showed that the existing crest protection levels for MRT stations are sufficient against more intense rainfall under the future projected climate change scenario. Site checks are currently being conducted and the full study is expected to be completed by 3Q 2022.

Beyond designing infrastructure to mitigate the risk of flooding, Operation Control Centres (OCCs) for MRT lines monitor water level and the frequency of pump operations. Drainage equipment at these underground facilities, such as pumps and flood protection barriers, are maintained regularly and inspected annually, in line with equipment manufacturers’ recommendations. During rainy seasons, the maintenance teams also step up their frequency of physical checks as an additional layer of assurance. Emergency flood response plans are also exercised regularly by agencies and operators, such as flood barrier installation refresher training for MRT station staff twice a year, to maintain staff currency.

To minimise obstruction to traffic flow during intense rainfall, PUB will identify low lying areas and roads which will have to be raised. In the event of bad weather causing passengers to be stranded on board vehicles, SCDF will lead evacuation efforts, with the safety of passengers as its top priority. If roads need to be partially or fully closed depending on the severity and extent of the flood, LTA will work with the SPF to minimise impact to traffic. This includes disseminating real-time traffic and road closure information to the public.

We will continue to invest in our public transport infrastructure to strengthen the resilience of our rail network and make journeys more convenient and seamless for commuters.