Nicole Highway incidence

[Linkster]

LTA has started to carry out repair as the first stage of recovery works. Concrete is being poured into the cracks in some areas at the perimeter of the incident site. This is to stabilise the ground and to prevent water seepage. LTA will carry out these works without affecting SCDF's operations in the area.

For more information please click http://app.lta.gov.sg/corp_press_content.asp?start=1002

 

[hangyong]

LTA has started to carry out repair as the first stage of recovery works. Concrete is being poured into the cracks in some areas at the perimeter of the incident site. This is to stabilise the ground and to prevent water seepage. LTA will carry out these works without affecting SCDF's operations in the area.

For more information please click http://app.lta.gov.sg/corp_press_content.asp?start=1002

wah kaoz... concrete alone is bad for preventing seepage of water man... those who stays in HDB (or rather those built by JTC) apts older than 25 years old will know.

 

[mervlam]

wah kaoz... concrete alone is bad for preventing seepage of water man... those who stays in HDB (or rather those built by JTC) apts older than 25 years old will know.

you said it yourself.. 25 years of wear and tear.

concrete may be the solution temporarily. More permanent techiques may be on the way.

 

[hangyong]

you said it yourself.. 25 years of wear and tear.

concrete may be the solution temporarily. More permanent techiques may be on the way.

eh... I din say that they are wrong in doing it wat... just saying that concrete ALONE is bad... maybe they have added other things?? I dunno man... all I know is, concrete ALONE is not good enough...

further, if they are adding concrete ALONE, and then cover the top with tar... I bet the road will be there for more than 25 years... and then what? problems again?

 

[Prismatic]

wah kaoz... concrete alone is bad for preventing seepage of water man... those who stays in HDB (or rather those built by JTC) apts older than 25 years old will know.

There are many types of concrete actually, and concrete is quite impermeable to water. Seepages occur mainly because of cracks in the concrete.

 

[mervlam]

eh... I din say that they are wrong in doing it wat... just saying that concrete ALONE is bad... maybe they have added other things?? I dunno man... all I know is, concrete ALONE is not good enough...

further, if they are adding concrete ALONE, and then cover the top with tar... I bet the road will be there for more than 25 years... and then what? problems again?

i didnt say you are wrong either. relax...

btw, i said temporarily

 

[hangyong]

There are many types of concrete actually, and concrete is quite impermeable to water. Seepages occur mainly because of cracks in the concrete.

yup, agreed, but because of the humidity in Singapore, it MAY cause breakdown of concrete at a faster rate. and cracks will appear with such deterioration.

once again, I wanna clarify that I am not opposing to what LTA is doing, what they are doing now is good. to stablise the ground. But to solve the problem for good (or at least a longer period), concrete ALONE is not good enough.

 

[mervlam]

There are many types of concrete actually, and concrete is quite impermeable to water. Seepages occur mainly because of cracks in the concrete.

typical answer from a civil engineer trainee.

and not to mention the corrosive chemicals in water and progagation of cracks due to stress and strain, which may be the reason why that temporary concrete tunnel wall gave way.

i'm just an electrical engineer trainee.. :sweat:

 

[Prismatic]

yup, agreed, but because of the humidity in Singapore, it MAY cause breakdown of concrete at a faster rate. and cracks will appear with such deterioration.

once again, I wanna clarify that I am not opposing to what LTA is doing, what they are doing now is good. to stablise the ground. But to solve the problem for good (or at least a longer period), concrete ALONE is not good enough.

Actually, I'm puzzled by why you would want to make such a statement at all.
Why would they want to solve the problem for good now? Once they stablized the soil, remove the debris, rescue everyone and done their accident evaluation, they are probably going to remove or redo the whole thing again to facilitate the construction of the MRT line. So in no way, they aiming for a permanent solution now.

And humidity is really a less important factor affecting concrete than rainfall, heat and excessive stress. Anyway, mervlam made a good guess to why the retention wall failed. The accident site is right next to the Kallang river, which place it in a marine environment. Concrete in a marine environment is exposed to sulfate attack in marine clay (though I would be surprised if they didn't consider this before construction).

Equally likely factors for the retention wall to failure could be a under-designed element strength, or soil movement due to water seepage through the soil locality.

 

[mervlam]

The accident site is right next to the Kallang river, which place it in a marine environment. Concrete in a marine environment is exposed to sulfate attack in marine clay (though I would be surprised if they didn't consider this before construction).

not so sure if it's marine clay. that area is reclaimed land. marine clay is used for reclaimation?

 

[hwchoy]

did anyone realise that the caving in area is reclaimed land? :think:

behind Golden Mile Complex is not reclaim land lah. That is part of the original coast line, which runs along the original Nicoll Highway. If you remember there used to be old stone-type "fencing" along Nicholl Highway, those were the embankment to the "sea" just like the old Esplanade.

 

[mervlam]

behind Golden Mile Complex is not reclaim land lah. That is part of the original coast line, which runs along the original Nicoll Highway. If you remember there used to be old stone-type "fencing" along Nicholl Highway, those were the embankment to the "sea" just like the old Esplanade.

it's reclaimed land... the embankment marks out the reclaimed areas donkey years ago.

 

[hwchoy]

it's reclaimed land... the embankment marks out the reclaimed areas donkey years ago.

where did you get this? AFAIK only Telok Ayer basin was filled in (not sure if even considered reclaimed) during colonial times. That's why some roads in Telok Ayer are curved (see from map) because it followed the Bay. Thian Hock Kheng temple was on the sea front at that time!

The Beach Road coast line and Tanjung Rhu area has been there since the mid 1800 when it appeared on etchings and paintings (now in the Museum).

I go along Nicholl highway a lot in the 60s (when it had the switchable middle lane and the Merdeka Lions) when I was a kid and even then the embankments were there and already looked old. Although the aroma along Kallang and Singapore River are a lot more "exotic" then :bigeyes:

 

[Prismatic]

The Beach Road coast line and Tanjung Rhu area has been there since the mid 1800 when it appeared on etchings and paintings (now in the Museum).

Actually ah, we can't tell for sure lah, unless we have proper surveying maps and all. And if there are embarkments, there are probably some sort of soil stabilisation done around there, or else where did you think the embarkment came from?

Careful, we are going OT here again.....

 

[hwchoy]

yah but that is not the same as reclaimation woh.

OK, maybe we misunderstand each other. For me reclaimation is like Changi Airport, Marina South, that kind. Telok Ayer Basin has been stated as reclaimation also, but I suppose the bay is only very shallow and not the same scope as Changi reclaimation.

OT! shucks! :sweat: :sweat: :sweat: if interested in Singapore geology we go start another thread. any geologist around here?

 

[Prismatic]

Reclamation don't really just mean filling up the sea lah.... It's just a term for converting or creating existing/non-existing land for use.
You can reclaim land from the sea by filling it up. You can reclaim land from swamp by filling it up too. You can also reclaim land from Toa Payoh for a Disneyland by blowing the town up too. We don't have to get so technical about the terms lah.

 

[innovas1]

i got this from the straitstimes website just now.

 

[reachme2003]

One detail which I am uncomfortable with. A photo which ST publish showed flames shooting up from under Nicoll Highway. Gas were detected by residents at Golden Mile. As of today's ST, LTA said it had no evidence of an explosion. I cannot reconcile the two together.

I expect more details out from today's LTA's new conference at 3pm.

Just saw on CNA's news at 3pm, a amateur video shows shooting flames.

 

[hwchoy]

maybe it didn't "explode", just burn off (like those refinery burning off excess gas). gas explodes if ignited in a confined space.

 

[reachme2003]

I am no expert. If residents at Golden Mile can detect gas, ie in an open space, I hate to imagine what it would be like in a confined space of up to 35m dept with severed gas pipe/s and working equipment around. Gas build-up in such scenario is unlikely to be weak and slow.