Success of Kuala Lumpur's dual purpose tunnel
First publishedin ITS International
Malaysia’s capital boasts a unique piece of infrastructure; a combined stormwater and motorway tunnel, the longest multi-purpose tunnel in the world.
Kuala Lumpur’s Stormwater Management and Road Tunnel (Smart) was conceived as a project under the Malaysian Federal Government to alleviate the flooding problem in the city centre. Although a booming city and the nerve centre for Malaysia’s economy, KL was built along the flood plains of the Klang River and, since its earliest days has been subjected to flooding.
In 1971, for instance, a serious flood lasted for five days; inundated some 445 hectares of land in the centre of the city, and resulted in extensive damage. Incidences of flooding have become more frequent in recent years.
The Smart project was implemented through a joint venture pact between MMC Corp Berhad and Gamuda Berhad with the Department of Irrigation And Drainage Malaysia and the Malaysian Highway Authority as the executing government agencies.
It was at the beginning of the design stage of a dedicated stormwater tunnel that the dual purpose concept was born – one which would simultaneously address both the Malaysian capital’s flooding and traffic management problems. Kuala Lumpur’s Stormwater Management and Road Tunnel (Smart)
Cost: US$515 million
Benefits: (over 30 year concession period):
• US$1.58 billion of possible flood damage prevented
• Up to $1.26 billion savings from traffic congestion
The MMC-Gamuda Joint Venture presented the idea of incorporating two major infrastructure components into one mega structure to the Government of Malaysia which gave the project the go-ahead in 2003.
Smart is a dual purpose tunnel, incorporating a double deck motorway within the middle section of a stormwater tunnel. It was completed on 30 June, 2007.
Smart tunnel is designed first and foremost for flood control and this role will always over ride its other role as a congestion relieving motorway. To ensure this protocol is maintained, the decision to close the motorway section for flood operation has been retained by the Government through its agency, the Department of Irrigation and Drainage, Malaysia (DID).
There are three modes of operation of the tunnel. In Mode I (for most of the time) there is no storm or low rainfall, which means there is no discharge of water into the tunnel in this mode.
The road section operates normally and traffic is able to use the tunnel from Kuala Lumpur city centre - Seremban Highway and vice versa.
Mode 2 - minor storm. When there are moderate or minor storms and the river flow at the confluence exceeds 70 cumsec (cubic meter per second), the Stormwater tunnel is activated to “semi-open” status by allowing diversion of water flow from the confluence of Klang and Ampang rivers through the lowest channel of the road tunnel section. The motorway section operates normally and there is no traffic disruption since only the lowest channel is being used at this juncture.
Mode 3 - major storm. When the FDS detects a reading at the river confluence of more than 150 cumsec and predicts a heavy and prolonged downpour, the Stormwater tunnel is activated to “fully open” status. The radial gates at the diversion weir are lowered to divert water flow in full capacity from the confluence of two rivers into the holding pond. At the same time, the entrances to the motorway section are closed to traffic while all vehicles in the tunnel are evacuated and the entire structure checked, a process that takes less than an hour.
Once the FDS indicates that the Mode 3 status is over and the weather is back to normal, flood water is pumped out of the tunnel and the tunnel is cleaned of mud and small debris.
In normal process of cleaning and inspection of the tunnel condition, Smart tunnel is reinstated within 48 hours after the water channelisation is made and traffic for the motorway section is allowed back for usage as normal thereafter.
Smart cost benefits
Smart tunnel has proven to be a success in meeting its primary and secondary objectives. Because of this infrastructure, areas such as Masjid Jamek area, Dataran Merdeka, Leboh Ampang and Jalan Melaka have witnessed no flooding incidents since Smart opened in 2007.
In May this year, DID (Department of Irrigation and Drainage) released the findings of a survey carried out on the first five years of operation of Smart.
Mode 3 operation was activated to prevent potentially severe flooding of Kuala Lumpur city centre a total of seven times: two times each in 2007, 2008, and 2012 (up to May) and once in 2011. Mode 2 operation, which does not affect use the road tunnel was activated dozens of time in the period.
In terms of its role in traffic relief, Smart has minimised the journey for cars into KL city centre from the southern gateway from the normal 20 minutes when using the federal road to only eight minutes when using Smart. Around 38,000 vehicles use the double deck motorway each day.
Putting a financial value these benefits, the DID survey concluded that, within the concession period spanning three decades, Smart is expected to prevent US$1.58 billion of possible flood damage and up to $1.26 billion savings from traffic congestion. The savings are likely to be significantly more, since these estimates are only for the duration of the concession – the tunnel has a design life of some 100 years.
A MATTER OF LIFE AND DEATH
Monitoring and safety systems in any road tunnel anywhere are of vital importance and in KL’s Smart these systems are even more critical; were anyone to be anywhere inside the road tunnel section when it is activated for stormwater relief, they would face certain death. So the SCADA monitoring and surveillance system has additional features that are unique in normal motorway tunnel operation. From a central control room which is manned 24/7, over 200 CCTV cameras, linked to an advanced automatic incident detection (AID) system keep watch on every section and can intervene when necessary – through the use of variable message signs or activation of first responder vehicles and personnel which are on permanent stand-by.
The control centre also monitors and operates the 38 sets of air quality monitoring equipment that analyses carbon monoxide, nitrogen monoxide, and particulate matter deployed throughout the upper and lower motorway decks. Depending on the equipment returns, four ventilation shafts, each containing eight sets of fans, can be activated. Control for the automated flood control gates is also incorporated within the SCADA system.
While Smart bristles with CCTV, when Mode 3 to flood the motorway decks is activated, barriers prevent any further traffic entering the tunnel. For safety reasons, cross-passage decks inside the motorway section placed at 250m intervals to act as emergency exits, have to be manually checked by personnel, along with ventilation/escape shafts which are placed at 1km intervals. The entire process, to ensure that there is no possibility that anyone could be inside the facility, takes from 45-60 minutes before the flood control gates are activated.
Re-opening the tunnel after an incident typically takes 48 hours. Although booms, barriers and filtration ponds prevent debris from entering the tunnel and causing damage to the fabric of the motorway section and its sensitive equipment, sediment carried with the water coats the entire surface. As a result, the installation needs to be pressure washed and all equipment checked.