Geospatial World II September 2010

Kuala Lumpur is a boomingcity and a nerve centre for

Malaysia’s economy. Topographi-cally, Kuala Lumpur was builtalong the flood plains of the KlangRiver and thus, since the earliestdays it was subjected to flooding.In 1971, the flood lasted for five

days and resulted in extensivedamage. About 445 hectares ofland in the city were inundatedand the cost of damage was esti-mated to be in the region of RM36million. Over the past decades,incidences of flooding havebecome more rampant and

according to a recent study, thecost of damage due to floods tothe whole country is around RM1billion a year out of which RM100million is borne by Kuala Lumpurcity centre alone. Besides the riskof flooding affecting the city centre,Kuala Lumpur has also been experi-encing road congestion issue due tothe booming growth in its economicactivities. One of the critical roadalignments heading towards andfrom the city centre is the southerngateway link that connects the cityto the southern part of the country.The traffic volume on this stretch

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Two issues, one solution

SMART TUNNEL I Mohd. Noor b. Mohd Ali

Geospatial World II September 2010

has seen a huge growth and analternative route to cater to furthergrowth was greatly needed.

To address both these issues,MMC-Gamuda Joint Venture pre-sented the idea of incorporating twomajor infrastructure componentsinto one mega structure to the Gov-ernment of Malaysia which gave theproject a go ahead in 2003.

Smart features

The Stormwater Management andRoad Tunnel, better known asSMART, started construction workin January 2003. The projectdemanded the effort and expertiseof many - from supply of two slurrymixshield tunnel boring machines(TBMs) of more than 13 metre diam-eter to solving the complex engi-neering issues of combining two dif-ferent uses in one tunnel, from sup-ply of bentonite and M&E fittings toemploying the workforce and theservices of international anddomestic leaders in their field. Partof the challenge was dealing withthe soil condition of Kuala Lumpurwhich mostly consists of karsticlimestone and alluvium with manycavities and pinnacles.

Hence, managing advance of thetunneling machines and progress-ing major surface and open cutworks to refining the operatingstandards and protocols for thesafest operations of the dual pur-pose facilities were of utmostimportance.

Early results of the 3D modellingof reflected features at up to 40 mahead were promising but the nec-essary sensors on the rotating cut-

terhead didn't survive the harshenvironment of the limestone exca-vation process and had to beremoved and improvement wasmade onto the casing for better andmore robust protection. Being ableto "see" ahead of the tunnel facehowever remained a high profileobjective and therefore other meth-ods of geotechnical survey tech-niques were also applied, such asmicrogravity, cross hole seismicsurvey, ground penetrating radarand 2D resistivity tomography. Themost beneficial of these was resis-tivity, a technique that detectschanging resistivity of features with-in the ground to identify potentialanomalies such as karst voids andfissured rock.

Mechanical and electrical

components

Smart Tunnel is a dual purpose tun-nel, incorporating a double deckmotorway within the middle sectionof a stormwater tunnel. It was com-pleted on 30 June, 2007. The com-pletion of the Smart Tunnel is attrib-uted to the implementation of inno-vative technologies and skilled teamplayers. Being the first of its kind inits concept as a whole, there wereindeed many firsts for the Smartteam. In dealing with the dual pur-pose tunnel, amongst the mostimportant components are the M&Eequipment that can withstand thedual environment conditions - bothwet and dry.

Smart operations

Smart Tunnel is designed first andforemost for flood control and as

such stormwater operation modewill always over-ride the motorwayoperation mode. To ensure this pro-tocol is maintained, the decision toclose the motorway section for floodoperation has been retained withthe Government through its agency,Department of Irrigation andDrainage, Malaysia (DID).

Three modes of operation:

MMooddee 11 - no storm. For most time ofthe year, there is no storm or lowrainfall, which means no diversionof water flow from the upstreamconfluence of the Klang River andAmpang River through Smart infra-structure to the attenuation ponddownstream in Taman Desa. Duringthis mode, the road section operatesnormally and the traffic is able touse the tunnel from Kuala Lumpurcity centre - Seremban Highway andvice versa. There is no discharge ofwater into the tunnel in this mode.

MMooddee 22 - minor storm. Whenthere are moderate or minor stormsand the river flow at the confluenceexceeds 70 cumec (cubic meter persecond), the Stormwater Tunnel is

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activated to "semi-open" status byallowing diversion of water flowfrom the confluence of Klang andAmpang rivers to the storage pondlocated upstream in Kg Berembang,Ampang, thereafter into the tunnel,and through the lowest channel ofthe road tunnel section and into theattenuation pond downstream inTaman Desa.

The flood detection system(FDS) operated by DID continuouslyand closely monitors any changes inweather conditions. The motorwaysection operates normally wherethere is no traffic disruption forthose driving through the tunnelsince only the lowest channel isbeing used at this juncture.

MMooddee 33 - major storm. When theFDS detects a reading at the riverconfluence of more than 150 cumecand predicts heavy and prolongeddownpour, the Stormwater tunnel isactivated to "fully open" status. Theradial gates at the diversion weir arelowered to divert water flow in full

capacity from the confluence of tworivers into the holding pond. At thesame time, the entrances to themotorway section are closed to traf-fic while all vehicles in the tunnelare evacuated.

This is to ensure that both theroad decks are empty and ready forflood water to be channelledthrough the tunnel to the attenua-tion pond. Sufficient time is allocat-ed to ensure that all traffic is evacu-ated before all the relevant gatessuch as the road gates, servicegates and emergency gates are acti-vated to allow the water to be divert-ed through the tunnel.

Once the FDS indicates that theMode 3 status is over and theweather is back to normal, floodwater is pumped out of the tunnelinto the attenuation pond and the tunnel is cleaned of mud andsmall debris. In normal process ofcleaning and inspection of the tunnel condition, Smart tunnel isreinstated within 48 hours after the

water channelisation is made andtraffic for the motorway section isallowed back for usage as normalthereafter.

Smart benefits

After operating for more than threeyears, Smart tunnel has proven tobe a success in meeting its primaryand secondary objectives. Throughthe Smart tunnel, areas such asMasjid Jamek area, Dataran Merdeka, Leboh Ampang and JalanMelaka have witnessed no floodingincidence since 2007.

In monetary terms, the tunnelhas managed to save around RM112million, based on the number ofpossible major floods that couldaffect these areas should there beno such infrastructure in place forKuala Lumpur city centre.

As for the traffic relief, SmartTunnel has been widely accepted asone of the preferred alternative byroad users for their journey into theKuala Lumpur city centre from thesouthern gateway and vice versa.The major reason for that is thetravelling time which has been min-imised from the normal 20 minuteswhen using the federal road to onlyeight minutes when using the SmartTunnel.

Besides these benefits, SmartTunnel project has also managed todevelop more experts in the tunnel-ing job where from the projectalone, it has groomed up to 200 localengineers who are now capable oftaking up any tunneling challengesanywhere in the world.

Mohd. Noor b. Mohd Ali

Head - Toll Ops & Public Relations

Syartikat Mengurus Air Banjir & Terowong SDN

BHD (The Stormwater Management & Road Tunnel)

mohdnoor@smartco.com.my

Geospatial World II September 201040

Operational modes of the SMART

Holding Basin

MMooddee II:: No Storm

StorageReservoir

Sg Kerayong

Inlet600,000m3

NorthernSection

Motorway Tunnel250, 000m3 Southern

Section

Outlet1,400,000m3 3,000,000m3

8%

750,000m3

TToottaall SSttoorraaggee CCaappaacciittyy3 million cubic meters at 3 main components

MMooddee IIIIII::Major storms

MMooddee IIIIII::Moderate Storms

Sg Klang