Where does the water from the SMART Tunnel go?

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• AI-generated Summary ✨

  Comments detail the technical aspects of the SMART Tunnel's water diversion and flood management functions, emphasizing its primary role in channeling floodwaters and secondary role in traffic flow. Many acknowledge its effectiveness during heavy storms, though some criticize its cost, design, and implementation, suggesting alternative solutions and broader urban planning measures. Overall, sentiments express pride in the engineering feat while recognizing ongoing challenges in flood control, infrastructure development, and public awareness.

• car_craze (Member) on Apr 01, 2008 at 6:09 pm

  The construction of the SMART tunnel was impressive and was shown on National Geographic some time ago. let’s hope that is well maintained so that it will give many years of efficient channeling of flash floods from the city.

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• feirouz7 (Member) on Apr 01, 2008 at 6:23 pm

  dude, i’m very impressive with this amazing engineering solution. I’m proud being a malaysian coz we have such this wonder in world. SMART primary objective is to divert water from “Kuala Lumpur” to outside. The road tunnel is just a secondary objective. So, hopefull all road user plan well ur jurney during raining season. “Kuala Lumpur” it self a word where all the mud gathered. What you aspect from this??

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• Parrot (Member) on Apr 01, 2008 at 6:32 pm

  I’m not in the position to criticise the merits of SMART, but your entry also implies KL is now choked with road traffic no thanks to the lack of efficient public transport, to the point that traffic jams may ensue when just one major road link is shut off. All the government had to show these last four years was the consolidation of two rail transport companies (which hasn’t seen any significant improvement of services), the establishment of a bus company which efficiency is also dependent on the volume of road traffic, mere promises of extensions for the PUTRA line, and even more highways and widened roads.

  With the way the country’s infrastructures continue to promote the use of cars in M’sia, traffic disruptions like these are simply not going to go away. Heavy rainstorms certainly won’t.

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• intermilan (Member) on Apr 01, 2008 at 7:08 pm

  what happened if there is too much water that the lake simply cannot take?
  haha! contigency plan for this wasn’t told at all, i mean if there is a plan.. lah.

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• hyundai (Member) on Apr 01, 2008 at 7:09 pm

  The water can be used to clean the tunnel… Good idea…

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• xenith (Member) on Apr 01, 2008 at 10:09 pm

  The water level looks high…
  Is it?

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• mystvearn (Member) on Apr 01, 2008 at 10:44 pm

  What happens when there is a massive storm, and even the reservoir gets full? Where does water from SMART ends up? I know that from recent floods, SMART proved itself capable of not making KL flooded

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• MaverickNeo (Member) on Apr 01, 2008 at 11:05 pm

  hyundai said,

  April 1, 2008 @ 7:09 pm

  The water can be used to clean the tunnel… Good idea…

  _________________________________________________________

  LOLZ!!

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• tolan (Member) on Apr 01, 2008 at 11:15 pm

  smart tunnel? not smart enough thou.. Sg Gombak overflowed near jalan ipoh and got flooded today. it just a 2 hour storm. I could see quite a large area was flooded from my office. Luckily the water drain away before evening rush hour. spent billions n still get flood. another good project wasted by poor execution. poor malaysians

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• v0ices (Member) on Apr 01, 2008 at 11:18 pm

  ORLY?

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• jackyyong (Member) on Apr 02, 2008 at 12:20 am

  Agree with what Parrot has said. The tunnel was originally designed to channel water. The traffic bearing idea only came in much later as an after-thought. So you can see that the government is really trying to alleviate problems with the roads for private vehicles in mind, not with other forms of public transport. The money wasted in building super highways (while slapping us poor road users with exorbitantly high toll price in the process) can instead be channeled to add extra train to the LRT or connecting more areas with rail services.

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• albagmane (Member) on Apr 02, 2008 at 1:01 am

  wat color of the water is different??? i cant see the difference leh…

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• techiesavvie (Member) on Apr 02, 2008 at 1:29 am

  i wish this tunnel can smartly swallow the storm water from sg inki back in my kampung too (sorry pun intended)
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  tolan said,

  April 1, 2008 @ 11:15 pm

  smart tunnel? not smart enough thou.. Sg Gombak overflowed near jalan ipoh and got flooded today. it just a 2 hour storm. I could see quite a large area was flooded from my office. Luckily the water drain away before evening rush hour. spent billions n still get flood. another good project wasted by poor execution. poor malaysians

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• abtm (Member) on Apr 02, 2008 at 7:11 am

  i’ve always think, is there a cheaper alternative to channel the flood water during a flood, i don’t think the tunnel helps to reduce congestion. i mean for example if you enter from Jln Tun Razak near RHB then exit further down the road near the airfield, you end up back in the jam again. You pay your money just for the extra few km of free driving…Why not just install a emergency water pump system which sucks the flood water to the same lake??

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• normaluser (Member) on Apr 02, 2008 at 7:59 am

  tolan, PLEASE learn the facts before commenting that the tunnel is a wasted project.

  The Smart Tunnel is designed to flush flood waters from the western Klang river, compared to the eastern Gombak river (Jln Ipoh area). The SMART system will divert excess stormwater away from the upstream of Ampang and Klang rivers through the Kampung Berembang holding pond in Ampang, a bypass tunnel and a storage reservoir in Taman Desa before it is released back downstream of the Klang and Krayong rivers

  That’s why the Jln Ipoh area is affected with flood, but not that serious as it subsided before the rush hour period.

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• normaluser (Member) on Apr 02, 2008 at 8:02 am

  oops it should be eastern Klang river, and western Gombak river…

  abtm says,
  Why not just install a emergency water pump system which sucks the flood water to the same lake??

  Huh, u think its easy & fast to pump thousand of cubic meters of water to be channelled out miles away?

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• bahari (Member) on Apr 02, 2008 at 9:13 am

  ramai salah anggap SMART tunnel ni.
  the main purpose is for flood prevention, not for traffic.
  so, kalau hujan lebat, memang patut tutup.

  the idea is good. tapi bila orang dah biasa guna, bila ditutup, dah jadi tidak normal. manusia serign kali terleka. maka marah2, sengal2.

  apapun, masa hujanlah kesesakan teruk berlaku. tu tak termasuk kereta laggar bontot kereta depan.

  kan best area2 KLCC, bukit bintang, pudu raya ada medan jalan raya bawah tanah seperti di New York.

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• bahari (Member) on Apr 02, 2008 at 9:14 am

  my comment does’t appeared?

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• baldwin (Member) on Apr 02, 2008 at 9:56 am

  suprisingly there wasnt any jam from sg.besi all the way through to Jln Istana went I went into the city between 5:30-6pm.. ..

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• fashraf (Member) on Apr 02, 2008 at 10:13 am

  Paul, the picture taken by E90 very impressive! :)

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• alexbaby88 (Member) on Apr 02, 2008 at 10:32 am

  They should have just built a bigger tunnel for the water channelling so they never have to close the road part of the tunnel even during heavy rain. Not so SMART.

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• bmpower (Member) on Apr 02, 2008 at 11:15 am

  for the current sitution.. it’s global phenomenon.
  TUn M maybe expect this as well before.. but this wasnt enough to solve the problem.

  As for coming years, maybe it gonna turn bad. Smart Tunnel was help much. but it do help. No doubt about it. I were like to think in another way. Must do all related action such as:

  Reduce global warming / at least KL warming factor as example : too much cars / bus bla bla on the road. each one generate carbon and heat. Subsidize more on public transport (remember what pak la la said wanted to cut off petrol subsidi , but where’s the money now?) Let say, you only need to pay 50cent – RM1, and the bus/lrt as quick as 7 minit each . Increase parking fees to avoid selfish malaysian bring all their cars to office but only one person per car :D . Taxi subsidized too..

  Planting many more trees in kl at where ever possible. This method to reduce faster flow water from rain to the river as known..

  Else.. we will still get flood, ‘banjir kilat’ etc as selfish as we are..

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• wacko (Member) on Apr 02, 2008 at 11:56 am

  Anyone work within KL city center wanna really get away with daily stress coming to work perhaps can think about moving out to stay at Ampang Jaya area. Using Ampang elavated hiway it takes u only barely 15 minutes from ur home to reach ur office’s doorstep & vice versa. what a pleasent daily chores!!!

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• wacko (Member) on Apr 02, 2008 at 11:59 am

  Hey dude! Just shift out and come to stay at Desa Pandan. only 10 minutes away to reach Bkt Bintang & KLCC areas right from ur home doorsteps. No need to bother about smart tunnel.

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• osh_kosh (Member) on Apr 02, 2008 at 12:09 pm

  albagmane said,
  April 2, 2008 @ 1:01 am

  wat color of the water is different??? i cant see the difference leh…
  ——————————–

  the water coming out from water gate r brownish lah bro.. see carefully..

  not surprise as the water from SMART tunnel must be all mix up with mud, debrist etc (coz suppost to be flood water right?).. :)
  ————————

  feirouz7 said,
  April 1, 2008 @ 6:23 pm

  dude, i’m very impressive with this amazing engineering solution. I’m proud being a malaysian coz we have such this wonder in world. SMART primary objective is to divert water from “Kuala Lumpur” to outside. [b]The road tunnel is just a secondary objective. [/b]

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• osh_kosh (Member) on Apr 02, 2008 at 12:12 pm

  that feirouz7 fella made his point… ‘The road tunnel is JUST a secondary objective’.. think about it (he’s right)

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• car_craze (Member) on Apr 02, 2008 at 12:20 pm

  Albagmane – enlarge the photo and you can clearly see the difference in the incoming muddy/yellowish color compared to the dark greenish blue lake waters.

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• jonnyblaze (Member) on Apr 02, 2008 at 12:45 pm

  There is a saying,

  “jangan mahu berak baru cari jamban”

  Proper water drainage management should have been incorporated into the development of Klang Valley from the very beginning, not after the infrastructures are all up and running.

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• madimat (Member) on Apr 02, 2008 at 1:30 pm

  typical Malaysian. Complaint, complaint, and complaint.

  The MAIN PURPOSE of the SMART Tunnel is to channel out excess water out of KL so you and all your expensive cars not get soaked and damaged in those muddy teh-tarik colored waters. It has proven this capability to us several times from numbers of previous heavy storms. For that reason, it has to be closed for a couple of days so that the Management can do a series of proper inspection, cleaning, testing, and so on so that the next time they opened it back, and you run your expensive cars through it, your expensive tyres wont get stuck in mud ! And they want to make sura that you wont get chased by some kind of mutant alligators or lizards. Got it..??!!

  The traffic flow purpose is used SECONDARY when the weather is all right, so you wont complaint later that this is another white elephant waste-of-money mega project bla bla bla only useful when it is flooding bla bla most of the time kosong useless banyak angin saja bla bla and all kind of complaints. It was their courtesy that the tunnel also to be used as a road tunnel so you and your expesive cars can reach your expensive Bangi or Nilai or Putrajaya homes on time for dinner. Is it waste of money? Imagine if the tunnel is to be built in 2015 or 2030 instead of a couple of years back. How much it will cost at that time? How about KL at that time..? nobody going to be in KL because it flood all day and there is nothing at all to take the water out. What will happen to all your expensive pubs and discos and hotels and all your businesses? tutup kedai loh.

  I am not blindly defending the tunnel or the people behind the idea of the tunnel or the cost of building it. But as far as I know, it at least served its purpose to avoid KL from heavy flood a few times. I am just pizzed off with the way some people who knows only to bashed a few small issues instead of looking at the overall bigger benefits the tunnel provided.

  Long live KL, and hope it wont stink.

  – peace.

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• Roti Naan (Member) on Apr 02, 2008 at 1:50 pm

  the tunnel is a fine idea. However, this is idea came about after many flash floods that took place in the heart of KL. Bet KL folks can recall all that incidents.

  Somehow rather, the development in KL and its surrounding is very rapid and sometimes all land are cleared and then hard paved, rendering the nature’s “sponge” to absorb water useless. There are hardly any trees or green space in KL that could effective soak in the water. The authority should do something about regulating the physical development in KL so water run-off can be dealt with without constructing mega flood mitigation projects that requires billions of ringgit.

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• en7yfl (Member) on Apr 02, 2008 at 1:58 pm

  Can somebody explain how this smart tunnel works? it seems like everybody has no idea how it works. According to my understanding, The water is not flow in the car lane, but under the car lane.

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• madimat (Member) on Apr 02, 2008 at 2:31 pm

  en7yfl said,

  Can somebody explain how this smart tunnel works? it seems like everybody has no idea how it works. According to my understanding, The water is not flow in the car lane, but under the car lane.

  ++++++++++++++++++++++++++++++++++

  Dont forget to catch “Malaysian SMART Tunnel” on National Geographic Channel (ASTRO Channel 555) if you got a chance. They will re-run the episode some day. It has all the stories.

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• osh_kosh (Member) on Apr 02, 2008 at 2:34 pm

  bravo bro madimat.. i couldn’t have explain better… :)

  en7yfl,
  AFAIK when there’s no flood the SMART tunnel will open all it lanes, but they can close the lower lane to assist the water flow (when the treat of flooding during raining storm exist)… they will fully close the SMART tunnel when there is a high chances of flood and fully utilised it as a mean to tranfer excess water.. & to my understanding, the water flow inside the tunnel itself (in the car lane).. correct me if i’m wrong

  btw, there’s NO ultimate solution in engineering… we need to compromise something… in this case, to fully prevent flood, u must have a lot of MULLAH.. why? we can build bigger SMART tunnel (in the 1st place), another SMART tunnel etc… but the cost? the geograpical constraints? don’t talk about the past, “should have been incorporated into the development of Klang Valley from the very beginning” etc. etc… we all know who we vote for.. live with it :)

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• wong (Member) on Apr 02, 2008 at 3:23 pm

  Some people already saying this mega project is a waste of money and some said should have done it from the very beginning,which is true?Few years ago we can always expect a monsoon season will be end of the year but now it can be any time,have to agree with madimat…

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• madimat (Member) on Apr 02, 2008 at 4:58 pm

  Dont forget to catch “Malaysian SMART Tunnel” on National Geographic Channel (ASTRO Channel 555) if you got a chance. They will re-run the episode some day. It has all the stories.

  +++++++++++

  sorry,.. correction. National Geographic Channel is on ASTRO 553, and not 555. harap maaf.

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• nobodyatuk (Member) on Apr 02, 2008 at 5:18 pm

  Just a thought, there should be some kind of early notice to inform of the tunnel closure to the public, could in the form of sms, radio/tv announcement or any other appropriate means so that the usual tunnel users could plan alternative route to go home. It wouldn’t be an easy operation but if there is a good coordination among the tunnel operator and relevant agencies, it should be successful…ofcourse not everybody would be smiling but the general public are taken care of.

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• mukhri88 (Member) on Apr 02, 2008 at 5:25 pm

  Ahaks oreng Key Ell… so sad with all the jams and flooding.. But living out here in the country I do miss all the metrosexual stuff in KL ie: Jazz festivals, theatre, cineplexes, KL football team, Baze, 11LA.. hehe..

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• marvel (Member) on Apr 02, 2008 at 6:54 pm

  mukhri88 said,
  April 2, 2008 @ 5:25 pm

  Ahaks oreng Key Ell… so sad with all the jams and flooding.. But living out here in the country I do miss all the metrosexual stuff in KL ie: Jazz festivals, theatre, cineplexes, KL football team, Baze, 11LA.. hehe..
  =============================================
  aha..don’t forget Riverbank,Beetlenut,Pyramid Club,Rainbow…wah in80’s and early 90’s KL were such a fun place to be…now it’s too overcrowded…

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• digiman (Member) on Apr 02, 2008 at 8:30 pm

  i wonder. when can m’sian people ever be happy about some of the projects the govt has done? not to say that there is an 100% good project. some are good some are bad. just like people, we are not perfect. unlike some of the condemner here, all complain, but offer no solution. there should be more people like nobodyatuk, providing positive remarks on how to make it better. though it might not be feasible, but i am sure there are other ways of doing it.

  i think its also due to the local newsprint. really good example of gossip journalist style (this includes The Star newspaper). writer: if you are reading this, I am sorry, but truely, it could have been written better.

  rather than just concentrating on the jam, the writer should have write up on the good point of closing the tunnel. its like looking at a glass half full or half empty.

  my 1 suggestion for the tunnel? if only it could be bigger and wider. otherwise fine with the whole concept of things. just feel really scared with the rumours that its cracking and stuffs.

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• bmpower (Member) on Apr 03, 2008 at 12:30 pm

  it’s wider and large enough.
  it height’s about 4 storey high building .
  told you, making a tunnel wasn’t an easy tast.. the larger you bore / ‘korek’ the more effect for the building on the surface ground.

  for the time being as i told above.. the rain is too much. and not enough trees or other method to slowdown the water flow to the longkang.

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• raybrig85 (Member) on Apr 03, 2008 at 1:04 pm

  aiyak..manyak komplen…x bsarla…it is really xpensive to korekla…for me…dat tunnel is insanely big…3 tingkat tu tunnel…one floor for water…another two for traffic flow from kl n frm seremban…its big…

  u cant xpect everything is perfect..in architecture n engineering world…there is no perfection…wat we can do..jz makes it nearly perfect…there a lot of constrain u hv to face…but u can make the constrain less…

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• osh_kosh (Member) on Apr 03, 2008 at 3:36 pm

  yesterday flood again at several places in Klang Valley…

  why not bring the ‘Monsoon Cup’ here?? LOL :)

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• paxter (Member) on Apr 03, 2008 at 5:19 pm

  put it this way lah ok, yesterday it rain like crap, and the traffic was so badly clog up (my office is very near pavillion) took the tunnel and got back 35mins later i live in ttdi… a colleague who lives in dsara. left the same time got back 1 hr +… 2 bucks on a bad traffic day is nothing.

  anyway if you do get a chance to watch the doco… you might contract the question why was the tunnel not set up a long time ago… the technology to bore a 4 story tunnel and to have a proven technology to manage the tunnel effectively during a storm is quite a leap, and ontop of that to have a city in the worse area possible area… and to top it all off a badly design city. That tunnel had to make sure it didnt burst the thousands of cables,pipes, etc… oh just to top it all off there is a huge batu kapur deposit below KL making it very unstable to build anything underground.

  City planners should be blamed for some of the traffic woes, but when morons start going into the yellow box to “be faster” during a bad traffic day i wish i had my pb gun…

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• Parrot (Member) on Apr 04, 2008 at 10:27 am

  ===quote===
  bahari said,

  April 2, 2008 @ 9:13 am

  kan best area2 KLCC, bukit bintang, pudu raya ada medan jalan raya bawah tanah seperti di New York.
  ===/quote===

  New York City doesn’t have extensive underground roadways. It has extensive underground subways and elevated railway lines, which is why only 48% of New Yorkers own cars, and only fewer than 30% actually drive to work. Let’s not forget the proposed congestion charges to be imposed in the city as well to discourage use of cars in the city.

  ===quote===
  madimat said,

  April 2, 2008 @ 1:30 pm

  I am not blindly defending the tunnel or the people behind the idea of the tunnel or the cost of building it. But as far as I know, it at least served its purpose to avoid KL from heavy flood a few times. I am just pizzed off with the way some people who knows only to bashed a few small issues instead of looking at the overall bigger benefits the tunnel provided.
  ===/quote===

  But the argument above fails to take into account the wider scope of development in KL and its effect on water levels. Even though KL has, since its beginnings, suffered from worse flooding (one such flood during the 1920s was waist deep) that were partially subdued with the construction of riverside levies, crappy development plans thereafter that opted for direct cost cutting (extensive pavement of natural ground, downing of trees with no equivalent replacement and channeling of rain water into the rivers) without consideration of their long term effects has dramatically increased the amount of rain water in rivers over the years. Rather than discuss the tunnel itself, why not focus on what could be done mitigating the risk of future flooding?

  ===quote===
  madimat said,

  April 2, 2008 @ 1:30 pm

  The MAIN PURPOSE of the SMART Tunnel is to channel out excess water out of KL so you and all your expensive cars not get soaked and damaged in those muddy teh-tarik colored waters. It has proven this capability to us several times from numbers of previous heavy storms. For that reason, it has to be closed for a couple of days so that the Management can do a series of proper inspection, cleaning, testing, and so on so that the next time they opened it back, and you run your expensive cars through it, your expensive tyres wont get stuck in mud ! And they want to make sura that you wont get chased by some kind of mutant alligators or lizards. Got it..??!!

  […]

  It was their courtesy that the tunnel also to be used as a road tunnel so you and your expesive cars can reach your expensive Bangi or Nilai or Putrajaya homes on time for dinner. […] What will happen to all your expensive pubs and discos and hotels and all your businesses? tutup kedai loh.
  ===/quote===

  That was an awful lot of generalisation, isn’t it?

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• madimat (Member) on Apr 04, 2008 at 3:01 pm

  Parrot said,

  bla bla bla.

  +++++++++++++++++++++++++++++

  well, sorry for all those awful generalisations i made. I just hope some day you can come out with a time machine of some sort so that you and I get back to 1920’s or 1970’s or 1990 something and advised the Mayor of that time to start a 500 years plan for KL.

  And how do I wish that from the very beginnings we filled the Mayor’s office with a hybrid species of genius and fortune teller so they can foresee what will happen in 2008 and beyond before allowing all those lousy and greedy developers and property tycoons from cutting out trees and digging up holes anywhere and everywhere they feel like to do it.

  uh,. maybe that wont happen here because we’re malaysian, right. Selalunya bila dah terantuk baru nak terngadah.

  But the good news is, you can still send letter about your “…. why not focus on what could be done mitigating the risk of future flooding? ..” to the planning office and fight for it. Then it is just to them whether want to read and consider it seriously or just do a 3-point throw to their dustbin.

  For me I see the tunnel just as another necessary facility; I like it so I use it, but if you dont like it, just ignore it and see it as an expensive giant drain that helps to take water out during raining season. Hate it so much because it cost you your tax money..? well I also one of those tax payers, like you.

  -peace

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• osh_kosh (Member) on Apr 04, 2008 at 3:53 pm

  well me too… i wish they use my money to build another SMART tunner & not sending another female polar bear to North pole & monkey to space (again).. LOL :)

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• dr_carz (Member) on Apr 05, 2008 at 6:46 pm

  BO COMMENT AT ALL!
  SORRY FOLKS I LIVE IN KUALA LIPIS
  NO JAM NO NOTHING JUST THE ROARING OF MY SWIFT SPORT ENGINE IS HEARD

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• raybrig85 (Member) on Apr 05, 2008 at 6:57 pm

  osh kosh,

  LOL…sokong

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• Abdul Bahari (Member) on Oct 29, 2008 at 1:18 pm

  I will start with this strong statement: The method of operation for the SMART tunnel that I have developed below provides the best possibility to minimize the interruption of the traffics flowing in and out of the SMART tunnel. If 50 ARI (See below) design spec was complied, the balance of probability suggests that the motorways of the tunnel was designed to close NOT MORE than two times in 50 years. ARI stands for Average Recurrence Interval in years.

  I’m NOT representing any party that has the authority to manage and operate SMART tunnel. I’m only an ordinary citizen that have a “gifted” knowledge to understand “extremely well” the operation and management of this kind of system.

  Before I go further please understand the most important design specification of this tunnel taken from the information given by the project’s proponent. Validity of this spec can be checked with SMART tunnel management.

  Relevant design specification

  1. Storm water design = 50 ARI. It means that the system is sized to deal with the biggest storm water/flash flood in 50 years.

  2. Storm water retention capability = 3,000,000m3 that flows in 4 hours, or 208m3/s of localized rainfall that falls in 4 hours. (Assuming the storm duration is 4 hours)

  Break down retention volume

  a) Intake retention pond Kampong Beremban + Outlet retention pond Taman Desa + SMART tunnel (Excluding motorways) = 2,750,000m3

  b) Motorways = 250,000m3

  c) Total retention capability, assuming Taman Desa outlet (tunnel outlet) cannot discharging due to flow bottle at downstream has been reached (worst case scenario) =3,000,000m3

  At glance, from a), b) and c) above it obvious that we can spare motorways from participating in flood control operation for almost at all times without experiencing significant reduction on the overall SMART tunnel storm water retention capability. This is true since the motorways represent only 8% of the total retention capability of the SMART system.

  1. Brief overall operational philosophy

  Sungai Kelang passes a few critical flood plains in KL. These flood plains are getting flooded fairly easy during high river flow of Sungai Kelang.

  When there is a heavy rainfall upstream from KL, Sungai Kelang water level in KL will eventually increase after a few hours, due to “the distance” factor. The volume of water associated with this rainfall may not high enough to flood the critical flood plains in KL since it occupies vast area along the river stretch from upstream to KL. However, more often, it is sufficient to reduce flood contrl capability of Kelang River within the KL areas.

  Assuming when Sungai Kelang water level has almost reached the top of its bank, then it follows by localized heavy thunder storm (Storm water). This rainfall carries the highest amount of water in 4 hours over the last 50 years, with the amount of 3,000,000 m3 (208m3/s). What will happen then? Answer: Water level will rise above its bank. Thus, flash flood starts to occur at the flood prone areas.

  We can prevent such flood if we can divert up to the maximum of 3,000,000 m3 of storm water to a man made temporary storage. We hold firm this water until the rainfall stops and the water level downstream the tunnel’s outlet has gone down. Then we release it slowly and safely so that there is no area will be flooded.

  This is exactly what the SMART tunnel should do. It was designed more towards to keep the storm water temporary rather than to divert it as many believes. This statement is based on the claim by the project owner.

  The Optimum Operating Schemes for the SMART Tunnel

  Stage 1: Normal Operation- Storm water is less that the design value (Up to 2,750,000 m3 in 4 hours)

  Storm water shall be allowed to take its natural path, i.e. Sungai Kelang, if its amount is less than a certain limit. The limit shall be set based on flood level (FL_Beremban) at Kampung Beremban’s intake (Sungai Kelang river bank’s side). The flood level is defined as the maximum allowable water level elevation, that, if it is not violated, no flood will occur at the protected flood plains downstream.

  When this limit is reached, by the definition of flood level, protected flood plains are under flood risk. Thus, the excess river flow upstream from flood plains, i.e. at Kampung Beremban shall be diverted to the tunnel for retention. This action will reduce the flow to the protected flood plains. As a result flash flood will not occur.

  At this stage, the sub operational objective is to maintain FL_Beremban constant. This sub objective is achieved by means of controlling the opening of the intake gate Kampung Beremban. The main idea is to match the excess storm water to the filling rate of the tunnel. By the same time water levels at the protected flood plain areas downstream are kept constant below the flood level.

  There should be no attend to be done to reduce FL_Beremban. By doing so, some space of the SMART retention volume will be occupied by “unharmed” storm water. This is counter productive since up to this time we have yet known how big the size of storm water is going to be. Thus, we need all the available space to deal with the “harmed” storm water.

  The amount of storm water that will be kept for retention, says in 4 hours is random in nature. It could be any value between 0 to 2,750,000m3. In this case, if the design of the motorways is really “safe” and water tight, then there is no need to close down the motorways. This is because without the volume provided by motorways (250,000m3) the desired storm water retention capability of 2,750,000m3 is more than enough to be used for storm water retention most of the time.

  Can we be caught off guard by flooding the motorways while an innocence man traps inside the motorways space when the actual storm water is greater than 2,750,000m3? The answer is that, it should not be the case since we can choose for not utilizing this space. Just close down the intake gate Kampung Beremban. No additional water will enter the tunnel. However, this means we have decided to divert minor flood flow up to an additional of 250,000m3 in 4 hours that we are in position to take it in the first place. The rational of this decision is that, it is better to flood the protected flood plains (surface flood) rather than to flood the motorways (tunnel flood) if we are not sure that the motorways have been fully evacuated.

  Filling up volume up to 2,750,000m3 of the tunnel, by design, will not affect the space that has been allocated for the motorways. Therefore, there is no need to stop the traffics. Statistically, as per design data there are at the average of 11 times a 4-hour storm water fall below this amount annually. There is only one that a 4-hour storm water violates this amount in 50 years. Thus, we can keep motorways “Business As Usual” or BAU while the remaining volume of the tunnel is used to curb flood almost all times in a year.

  Stage 2. Emergency operation – Storm water is between 2,750,000 and 3,000,000m3 in 4 hours

  How do we know that we have to move to this stage? If the tunnel has been filled up to says 2,500,000m3 at filling rate of 208m3/s (Design peak flow of the storm water) but FL_Beremban has yet shown any tendency to go down. This indicates high flow is sustained. We need to engage Stage 2.

  Evacuation plan has to be activated when the SMART tunnel has been filled says at 2,500,000m3, or 250,000m3 before the space for the motorways has to be utilized too. Taking the maximum allowable filling rate of 250m3/s (Slightly above the average design flood of 208m3/s in 4 hours), it takes exactly 1000 additional seconds (17minutes) to fill up the tunnel with additional water of 250,000m3. This is sufficient time to evacuate all traffics in the motorways minus emergency evacuation, taking the average speed of the traffics is 60km/h and the total distance between the entry and exit point is 10km. We need about 10 minutes to travel the entire distance of the tunnel under normal condition (no breakdown). Lead time for evacuation and Emergency Response Plan (ERP) shall consider the worst case scenario that traffic movement may not be as smooth as expected. We leave to the management of the system to come up with this one.

  Filling up motorways shall be done from bottom to top (outlet to inlet). There are two reasons for this suggestion: 1) If anybody get traps in the motorways without SMART operator’s knowledge, he or she still has a great chance to survive by driving up to the tunnel inlet, or trying to SOS the operator. The fact is that the tunnel inlet is located at higher elevation than the outlet. Filling up the motorways may take roughly about 1000 seconds, of 17 minutes. Filling up the tunnel from inlet provides almost no chance for he or she to survive (2) Natural way to vent the air out of motorways to prevent air lock. Air lock can cause the tunnel to vibrate badly. It is possible this vibration will cause the tunnel to collapse. Filling from top down cannot guarantee the air lock scenario may not happen. However, it is true that the operation scheme can be designed to prevent such scenario from occuring by means of mechanical and control system interlocking.

  Statistically, scenario in stage 2 is expected to occur at most twice in 50 years.

  Stage 3: Storm water is greater than the design value

  The retention capability of 3,000,000m3, including the space for motorways has been filled completely. But yet FL_Beremban doesn’t seem to go down. The design limit for retention capability of the tunnel has already been reached. We are entering the difficult scenario. We should have Emergency Response Plan (ERP) long before reaching this stage. I will show the important and critical operational issues only. Complete ERP will not be discussed.

  There are two options that the SMART tunnel can be used for flood mitigation. We call them A) passive operation and B) pro active operation.

  A) Passive operation

  It is as simple as closing down intake gate Kampung Beremban. The SMART tunnel, now, takes it natural stand. It does not participate in flood mitigation in any way other than holding 3,000,000m3 of the storm water. Flood plains at downstream have lost their savior. They are on their own to face the impending flood.

  Will it going to be any disastrous legal action taken by the affected parties, aftermath? It depends on written agreement between the SMART management and the stake holders. In this case, stake holders are the flood victims. As far as scientific and physical point of view, flood victims cannot win their case in the court of law. This is because nobody on earth is expected to have the ability to prevent natural disaster. Flood is one of the recognized natural disasters.

  When I explain to my friends about this subject, one of the popular questions is, “Why the design engineers choose not to take any amount of storm water?” Actually, we cannot design this kind of system to take any amount of storm water. We can decide the amount that we want, but not any amount. The amount of design storm water is associated with design ARI. For example,

  30 ARI is equivalent to 2,750,000m3 of storm water in 4 hours (Example only- may not be numerically accurate)

  50 ARI is equivalent to 3,000,000m3 of storm water in 4 hours. ( The design value)

  2500 ARI is equivalent to 6,000,000m3 of storm water in 4 hours (Example only-may not be numerically accurate)

  Probable Maximum Storm (PMS) > 10000 ARI is equivalent to 18,000,000 m3 of storm water in 4 hours. (Example only-may not be numerically accurate)

  It is normal to choose any value between 50 to 200ARI for storm water management depends upon the desired risks of the protected flood plains can effort to take. Note that the lower the risk, the higher the design cost. For example if we choose to design according to 2500 ARI, then we need to design the second SMART tunnel, identical to the current one. Then the capital cost will be two times higher. The chance is, in fact >75% chance that 2500 ARI storm water may strike 625years or longer from now! If we have the second SMART tunnel, then, what we are going to do with it for the first 624 years?

  B) Pro active operation

  This operation may be the most complex one. It may lead to legal action aftermath unless the Standard Operating Procedure (SOP) has been approved by relevant authorities such as JPS, Home Minister, Datuk Bandar’s Office and the Parliament.

  We still have the scenario that extremely high river flow flowing to the critical flood plains in KL. The SMART tunnel has been paralyzed while holding 3,000,000m3 of storm water over the last 4 hours. The river flow may be as high as 400m3/s. How long this high flow is going to last? We have yet to know.

  What the SMART tunnel could do is trying to divert a portion of the water from Sungai Kelang (inlet) to Sungai Kerayung (outlet Taman Desa). Says we chose 100m3/s. Then flood flow to the protected flood plains downstream after intake Kampung Beremban becomes 300m3/s instead of 400m3/s. If A) approach is engaged, then the flow will be 400m3/s. All river flow will be passed to Kampung Beremban downstream.

  The SMART tunnel changes it function from retention to diversion. However, SOP for effective operation shall be done based on which downstream has higher priority to be protected from flood. We have two areas namely, 1) Sungai Kelang downstream 2) Sungai Kerayung downstream.

  As mentioned above, it is extremely important to resolve potential legal conflict since the SMART tunnel does not take natural stand. To a certain extent, it decides which areas to be flooded and by how much. This is the tricky part. Poor handling, the management of the SMART tunnel may be challenged in court of law.

  If I was allowed to reccomend, go for A) above if Stage 3 operation has to be activated.

  Thank you.

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