The Global Urbanist

News and analysis of cities around the world


The waterline is rising on environmental risks threatening Bangkok's successful MRT

Monsoon rains cause regular flooding in Bangkok, and the city's underground MRT deploys simple measures for effective flood risk control. However, with expansions planned over the next ten years, concern is emerging over adequate responses to climate change, earthquake risk and rising sea levels. Serious thought now could save millions in retrofitting and damages, not to mention loss of life, as Rowan Fraser describes.

Rowan Fraser

Cities: Bangkok

Topics: Transport, Private sector governance, City finances, Climate change, Earthquakes, Flooding and storms

The raised entry to this underground MRT station prevented flood waters from entering in 2011. Photo © Exploring Tourism, reprinted with permission
The raised entry to an underground MRT station in dry weather. Photo: Rowan Fraser
A slot in the floor and glazed wall of an underground MRT station entry shows where a 1.3-metre steel barrier can be raised, preventing flood waters from entering the station concourse areas. Photo: Rowan Fraser
An underground MRT station platform. Photo: Rowan Fraser
Bangkok's Chinatown under flooding. Photo © Atsushi Hariu, reprinted with permission
Photo © Atsushi Hariu, reprinted with permission
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In a city notorious for bad floods and bad traffic, the successful operation of an underground mass rapid transport system requires systematic risk management. Fires, traffic incidents and civil unrest all threaten the smooth functioning of Bangkok's MRT, but the greatest risk continues to be flooding. As the monsoon rains settle in for 2013, and with a new line of the MRT opening shortly, I paid a visit to the MRT office to discuss flood risk management in their system.

Bangkok's MRT is an ambitious project. Consisting of a projected 10 lines, both above and below ground, and over 200 stations, the MRT system will be assembled over the next 10 years — economy and politics permitting. Already the majority of lines are under construction with many due for completion late in the decade or the early 2020s. The result will be an extensive, efficient transportation system for this metropolitan region of 14.5 million people.

Current flood risk: well managed through effective measures

Thanks largely to a suite of simple but effective flood control measures, the MRT performed well during the devastating 2011 Thailand floods which saw parts of Bangkok submerged in up to two metres of water and caused an estimated $45bn in damages nationally.

The only underground MRT line currently in service is the Blue Line, operated under a 25-year concession by Thai company Bangkok Metro Public Company Ltd (BMCL). From the outset, BMCL has focused its risk management on flooding, using simple measures to control flood risk. All entrances to the MRT have been raised approximately 1.0 to 1.5 metres above street-level — the user must climb a short flight of steps before descending to the ticket halls. Each entrance is fitted with steel flood barriers which can be raised an additional 1.5 metres during floods. The tunnels are constructed to withstand heavy pooling of water and water seepage. And if flood water does penetrate the system, there are pumps for water removal and a well-trained team operating under an Incident Command System backed by intricate monitoring technology.

Flood control measures are based on a projected maximum flood depth of 3.3 metres, using flood data for Bangkok stretching back 200 years. However historic data doesn't consider climate change, and the increases in rainfall, storm severity and sea level it predicts. As these changes are beginning to take on greater reality, BMCL is beginning to see the need to address new and as yet unconsidered risks.

New risks: climate change and earthquakes

Chatchaporn Triwimol, safety and quality manager at BMCL, readily agrees that new risks require attention. "There is the risk of climate change but also the risk of flooding from the Thai Gulf. So far, flooding has been from the [Chao Phraya] river," he said. Bangkok is a low-lying city, with much of it below sea level, and subsidence is only making it worse. While the local government has put in place a series of plans and policies aiming at combatting the risk of seawater intrusion to the city, real implementation has yet to begin.

In addition, "nowadays there are more and more earthquakes being felt in Bangkok", said Chatchaporn, "but when the system was getting designed, earthquake risk was extremely low. We may need to begin to review the earthquake risk."

The transport authority MRTA is reporting good progress on most current line extensions and new line projects. These include the almost-complete Purple Line (32 stations, 43 km) and extensions to the Blue Line (adding over 20 stations and about 30 kms) which will open over the next year. With new stations being built every month, and new kilometres of line being laid constantly, new risks must be factored in now to avoid costly retrofitting, as well as damages, loss of life, and reduced revenues.

This is even more important given the planned expansion over the next decade to a total of seven lines stretching across the Bangkok metropolitan region, 69% of which could be under sea by 2100 according to a recent World Bank projection. Without adequate climate change adaptation and risk control measures for related storms and flooding, the MRT will not only put users at risk, it will also endanger the health of the city's economy.

Above all, the bottom line

All of these considerations are framed within the overall need for economic viability. The Blue Line is the only line operated by BMCL (other lines are owned by other companies) and it is currently operating at a loss. This is common in the first half of an infrastructure concession, where heavy capital outlays (such as trains, operations systems, communications systems, etc.) are amortised slowly. It is for this reason that most concessions last 25 to 35 years, sufficient time for companies to offset initial costs and generate a profit.

For this reason financing costly retrofitting in response to climate change will be a struggle for BMCL, but does the responsibility lie with them? Or should this risk be borne by local government? Indeed, who is responsible for covering the cost of controlling disaster risk in urban systems? After all, the MRT is a vital public service and critical infrastructure for Bangkok's continued growth and functioning. Managing environmental risk gets a lot more complicated, and often expensive, when climate change is factored in, and successfully managing such risk will demand closer collaborations between government and business and new financing set-ups. Consensus must be built based on a shared knowledge of the risk, and the cost and requirement of controlling this.

To cover the cost of adaptation for the MRT, a few key moves from city government could make all the difference. Most importantly, the MRTA should award BMCL further concessions to operate new lines in the system. These should allow the BMCL to realise and optimise what are currently only potential economies of scale and network economies in the MRT system. At the same time, future concessions should oblige the company to immediately begin with adaptation works using the increased revenues to partially finance adaptation. In addition, the city should charge private vehicles for driving through the city centre, similar to London's congestion charge, and direct the revenue earned to financing long-term adaptation of public transportation systems as well as encouraging use of these systems through the charge itself. Similarly, the national government should strategically re-evaluate its schemes for reduced petrol prices and increased car ownership (if only in the Bangkok metropolitan region) to provide further subsidy for adaptation.


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