BTS Skytrain management says station structures able to support protesters

[Lakegeneve]

This is one of those lost in translation type of articles.

Pity that it wasn't posted in context as it derives from a few articles in the thai press and on facebook, the original concern gets lost, then people make a diverse range of comments generally missing the original point. There is no concern about the stations which are of course designed to support 2 fully loaded 6 car trains + completely full platforms + a completely crowdd mezzanine area + a dozen or so adult elephants + a bunch of highly bloated thai politicians full of hot air! (Okay perhaps not that last lot!)

Some concerns have been expressed in the thai press and on a couple of FB sites regarding the structural integrity of the barriers at pedestrian links and access areas - NOT the STATIONS per say - which link to station entry points. Other concerns abotu stairs leading up to BTS stations which the BTSC acknowledges could be a concern.

Here is an example of one of the pics;

The left side is Silom and what I believe to be the link to Central Silom at the east end of the station. The right pic is Asoke and shows the area which is outside Terminal 21 - technically nothing to do with the BTS as it was built by the center.

http://www.manager.co.th/iBizChannel/ViewNews.aspx?NewsID=9560000140255

https://www.facebook.com/photo.php?fbid=720372124659280&set=a.713297418700084.1073741845.648121061884387&type=1&relevant_count=1

These pics are I assume from the lunch time rallies of last week held for approx an hour. The red circles mean nothing other than the person who made the posted it is questioning if the vertical barriers are strong enough. The FB poster is merely pointing out that the joints may be placed under some strain if a large amount of pressure is applied from a crowd of people placing simultaneous horizontal force on the barriers.

Now this might be a valid concern if the density and force of people was enough to result in a structural failure thus resulting in people falling down to street level. That would be just a valid concern if - as does often happen - a concert was taking place in a shopping center or some celebrity was doing a promo event in the area. Large crowds assemble all of the time and seek a vantage to view proceedings.

That may be a valid concern and I'm not a structural engineer but in both photos I'd suggest that in fact there is actually not that many people leaning on or against the barriers to cause any major concern. (Given the incidence of sink holes on major roads there is possibly more chance of a bunch of protesters disappearing into a collapsed section of road)

Perhaps, a structural engineer can offer an opinion?

[Lakegeneve]

Here is another pic I just spotted on another Nation article, http://www.nationmultimedia.com/politics/Yinglucks-pleas-are-mere-wordplay-to-her-opponents-30219323.html

This shows the pedestrian link between Chitlom and Siam BTS stations, specifically between Siam stn & Ratchaprasong intersection. I'm guessing that it shows the west bound lane of Rama 1 thus the view is east towards Ratchaprasong.

This link has nothing to do with the BTS. It was built and funded by the BMA and private funding, CPN and the Ratchaprasong Business Assoc (or whatever their exact name is). It has private security guards which patrol it and close it each night.

[Thainy Tim]

This is all incorrect information from the BTS management, as they are relying on figures of a new build structure. The architects are totally correct.

When they built the Mall round here 6 years ago, the load capacities would have been what was on paper in the building inspector's report, but as quickly as 4 years and I was walking around it looking at all the cracks opening up in the concrete of the elevated concourses.

Cracking of concrete around the steel reinforcements severely compromises the integrity of the overall load bearing capacity. I know this for a fact, if you don't believe me, download the episode of 'I shouldn't be alive' about the 1995 Sampoong department store collapse in Seoul SK. The structure was overloaded but coped for a few years under the strain, but once cracks appeared in the concrete, the whole thing became a ticking time bomb. The documentary goes into detail about structural integrity.

When I look at almost everywhere in Thailand, I see cracks all over the concrete. Hotels, BTS and even my own house. They don't really know how to work with concrete here.

Then to add to this. While people are moving about (especially walking) the initial impact force of a footstep is actually almost double the weight of the individual. If running or jogging it is more like two and a half times the actual weight.

So when you add together compromised load bearing capacity and increased load by movement especially by masses of people, then your whole design strength theory goes out of the window. Especially if you already have lots of equipment on the floor already such as vending machines, ticket machines etc.

Edited November 12, 2013 by Thainy Tim

[BruceSmith]

400kg/sqm seems very low.That's just 8 people weighing 50kg each. If it was super-crowded the weight could possible be more than that.

Even more scary (and probable):

3-4 expats weighing 150kg each

and expats just love to protest

as we all very well know

[whybother]

400kg/sqm seems very low.That's just 8 people weighing 50kg each. If it was super-crowded the weight could possible be more than that.

Even more scary (and probable):

3-4 expats weighing 150kg each

and expats just love to protest

as we all very well know

Do you really think 3-4 expats weighing 150kg each can fit in 1 square metre? Lucky to get one.

[BruceSmith]

@whybother

"Do you really think 3-4 expats weighing 150kg each can fit in 1 square metre? Lucky to get one"

Most of the prime specimens I’ve seen are flat on one side (back) and semicircular on the other (front)

Now:

Imagine 4 teletubbies with their backs to a pole.

Scary anywhere - not only on the BTS.....

Edited November 12, 2013 by BruceSmith

[wprime]

They should put all the red shirts into MRT stations to protest, give them firecrackers too, that should enhance their protests.

[Thainy Tim]

BTW... 400 KG/M2 Is piss poor by most standards. Almost certainly hovering around the legal minimum. After a few years, it won't be anywhere near that capability.

Just another case of someone with no idea arguing with people who are experts in the field.

Here is something that will open your eyes to impact force versus stationary force.

a steel ball weighing about 8.5KG sat on a hard surface will have have a force of 8.5KG, but an 8.5KG steel ball dropped from only 4ft onto a hard surface will have an impact force of approx 400KG.

Edited November 12, 2013 by Thainy Tim

[Minnehaha]

400kg/sqm seems very low.That's just 8 people weighing 50kg each. If it was super-crowded the weight could possible be more than that.

Even more scary (and probable):

3-4 expats weighing 150kg each

and expats just love to protest

as we all very well know

I have been avoiding the BTS for this very reason.

I shudder each time I am through Asoke during rush hour. I dont believe the OP has factored in ATM machines, kiosks selling crap, and so on. We all know lots of stuff here gets a spec to build and then the contractors do what they like.

[forumuser10]

400kg/sqm seems very low.That's just 8 people weighing 50kg each. If it was super-crowded the weight could possible be more than that.

If the weight more than 50 kilo each, these 8 people will not be able to fit within 1 square meter.

[Lakegeneve]

This is all incorrect information from the BTS management, as they are relying on figures of a new build structure. The architects are totally correct.

When they built the Mall round here 6 years ago, the load capacities would have been what was on paper in the building inspector's report, but as quickly as 4 years and I was walking around it looking at all the cracks opening up in the concrete of the elevated concourses.

Cracking of concrete around the steel reinforcements severely compromises the integrity of the overall load bearing capacity. I know this for a fact, if you don't believe me, download the episode of 'I shouldn't be alive' about the 1995 Sampoong department store collapse in Seoul SK. The structure was overloaded but coped for a few years under the strain, but once cracks appeared in the concrete, the whole thing became a ticking time bomb. The documentary goes into detail about structural integrity.

When I look at almost everywhere in Thailand, I see cracks all over the concrete. Hotels, BTS and even my own house. They don't really know how to work with concrete here.

Then to add to this. While people are moving about (especially walking) the initial impact force of a footstep is actually almost double the weight of the individual. If running or jogging it is more like two and a half times the actual weight.

So when you add together compromised load bearing capacity and increased load by movement especially by masses of people, then your whole design strength theory goes out of the window. Especially if you already have lots of equipment on the floor already such as vending machines, ticket machines etc.

This was what the thread needed so thank you. A few queries if your feel comfortable to answer any.

1) I do remember the Seoul store department collapse and indeed viewed a doco on it many years ago. However, wasn't the main issue there that Korean construction companies were corruptly saving monies by not building to whatever the load bearing standard was. I seem to recollect that some 25-30% of all buildings in Seoul had to be retrofitted and strengthened once the practices of the industry came to light after a post Sampoon dept store investigation commission was established. Is that correct?

2) Which The Mall do you refer too.

3) You mention that you have seen cracks in concrete at the "BTS". Do you mean in the station superstructure proper and the main supporting beams or in access points and zones such as pedestrian links and or stairs. I think being specific is most important in the context of this discussion.

Personally, I've not seen obvious, large cracks within the station superstructure but then I am not looking for them either. Some cracking of concrete barriers which run along the viaduct - a few have actually fallen down to the rd over the years.

4) The 400kg/sqm load bearing BMA standard that is mentioned in the article seems to refer to BTS access points, "while skywalks and walkways linking stations can carry 400 kg/sqm following standards set by the Bangkok Municipality." These are the areas of concern referred to in the article, "Four at risk points on Skytrain stations, as warned by architects, are ticket offices, skywalks and walkways, staircase rails and escalators."

You stated "400 KG/M2 Is piss poor by most standards. Almost certainly hovering around the legal minimum. After a few years, it won't be anywhere near that capability." Thus, I would infer that a number of walkways, stairs and pedestrian links would not currently be up to that "piss poor" standard given that most have been open for between 10-14 years. What capability would you guess it would be after a few years?

5) Further, based on what you have written I would surmise that the these areas - walkways, skylinks - IF at risk of failure are more at risk to do so during periods of crowded peak transport use where there is increased load movement from many people walking along them to/from a BTS station than compared to an incidence of protest overcrowding where most people are stationary on the structure. Is that a reasonable supposition? (Which doesn't exclude failure due to a large stationary crowd of people on the structure.)

I'm not asking for a professional analysis here but I am interested in your response to the proposition put by the poster 2 posts above that he 'avoids the BTS' and 'shudders every time at Asoke during rush hour'. Seemingly, that it is prudent to avoid certain skywalks, links * ticketing areas on the BTS system during peak periods due to the risk of structural failure. (I'm leaving aside the protest crowd issue).

[biplanebluey]

People can bring down structures that can easily support the weight.

Have you ever noticed the army stops marching and "break stride" to cross bridges and other structures?

The unnatural rhythm of marching can easily cause even the strongest structures to fail, if the marching frequency matches that of the structures weakness.

If the protesters all decided to jump repeatedly, or even sway in unison, those BTS structures will surely fail.

Sent from my iPhone using Thaivisa Connect Thailand mobile app

Put up notices "DO NOT JUMP OR SWAY IN UNISON"------------------------ Problem solved

[biplanebluey]

This is all incorrect information from the BTS management, as they are relying on figures of a new build structure. The architects are totally correct.

When they built the Mall round here 6 years ago, the load capacities would have been what was on paper in the building inspector's report, but as quickly as 4 years and I was walking around it looking at all the cracks opening up in the concrete of the elevated concourses.

Cracking of concrete around the steel reinforcements severely compromises the integrity of the overall load bearing capacity. I know this for a fact, if you don't believe me, download the episode of 'I shouldn't be alive' about the 1995 Sampoong department store collapse in Seoul SK. The structure was overloaded but coped for a few years under the strain, but once cracks appeared in the concrete, the whole thing became a ticking time bomb. The documentary goes into detail about structural integrity.

When I look at almost everywhere in Thailand, I see cracks all over the concrete. Hotels, BTS and even my own house. They don't really know how to work with concrete here.

Then to add to this. While people are moving about (especially walking) the initial impact force of a footstep is actually almost double the weight of the individual. If running or jogging it is more like two and a half times the actual weight.

So when you add together compromised load bearing capacity and increased load by movement especially by masses of people, then your whole design strength theory goes out of the window. Especially if you already have lots of equipment on the floor already such as vending machines, ticket machines etc.

This was what the thread needed so thank you. A few queries if your feel comfortable to answer any.

1) I do remember the Seoul store department collapse and indeed viewed a doco on it many years ago. However, wasn't the main issue there that Korean construction companies were corruptly saving monies by not building to whatever the load bearing standard was. I seem to recollect that some 25-30% of all buildings in Seoul had to be retrofitted and strengthened once the practices of the industry came to light after a post Sampoon dept store investigation commission was established. Is that correct?

2) Which The Mall do you refer too.

3) You mention that you have seen cracks in concrete at the "BTS". Do you mean in the station superstructure proper and the main supporting beams or in access points and zones such as pedestrian links and or stairs. I think being specific is most important in the context of this discussion.

Personally, I've not seen obvious, large cracks within the station superstructure but then I am not looking for them either. Some cracking of concrete barriers which run along the viaduct - a few have actually fallen down to the rd over the years.

4) The 400kg/sqm load bearing BMA standard that is mentioned in the article seems to refer to BTS access points, "while skywalks and walkways linking stations can carry 400 kg/sqm following standards set by the Bangkok Municipality." These are the areas of concern referred to in the article, "Four at risk points on Skytrain stations, as warned by architects, are ticket offices, skywalks and walkways, staircase rails and escalators."

You stated "400 KG/M2 Is piss poor by most standards. Almost certainly hovering around the legal minimum. After a few years, it won't be anywhere near that capability." Thus, I would infer that a number of walkways, stairs and pedestrian links would not currently be up to that "piss poor" standard given that most have been open for between 10-14 years. What capability would you guess it would be after a few years?

5) Further, based on what you have written I would surmise that the these areas - walkways, skylinks - IF at risk of failure are more at risk to do so during periods of crowded peak transport use where there is increased load movement from many people walking along them to/from a BTS station than compared to an incidence of protest overcrowding where most people are stationary on the structure. Is that a reasonable supposition? (Which doesn't exclude failure due to a large stationary crowd of people on the structure.)

I'm not asking for a professional analysis here but I am interested in your response to the proposition put by the poster 2 posts above that he 'avoids the BTS' and 'shudders every time at Asoke during rush hour'. Seemingly, that it is prudent to avoid certain skywalks, links * ticketing areas on the BTS system during peak periods due to the risk of structural failure. (I'm leaving aside the protest crowd issue).

interesting reading-------

[maake55555]

Lets hope so, I travel on BTS a lot and would not want to fear for my safety because of too many people on the station ramp.

[HereIAm]

but the BTS should not be allowing this to happen.

Little it can do. BTS can't keep protesters away from clambering on the walkways and staircases. The escalator, the trains and the electrical systems lights, etc, are all it can switch off. Anything it tries to do beyond this would invite angry reactions which could easily escalate to looting, arson and worse, going by the track record of the lunatics who are given a free run during these so-called protests. Sometimes it is good judgement to roll with the punch and allow relatively peaceful access to the stairs and bridges rather than risk a bigger and unforeseen reaction which in hindsight might seem foolish to have not foreseen.