Ramp of Chinese Yangmingtan Bridge collapses only after 9 months of use

[Lyon Wonder]

The ramp of the brand-new Yangmingtan Bridge in china in the city of Harbin has collapsed, with 3 reported fatalities. Judging by news photos the section that collapsed appears to be a UCEB.

http://photos.mercurynews.com/2012/08/24/photos-bridge-collapse-in-china-kills-five-on-friday-august-24-2012/

The Yangmingtan Bridge was in use for only 9 months before the section collapsed.

http://usa.chinadaily.com.cn/china/2012-08/25/content_15705009.htm

Collapse of bridge raises question over construction quality

Updated: 2012-08-25

Three people were killed in a bridge collapse in Harbin on Friday, renewing worries over the quality of Chinese infrastructure amid a construction boom across the nation.

The bridge – which cost $300 million and was in use for less than a year – was at least the sixth bridge to collapse in little more than a year in China.

The ramp, about 3.5 km from the main span of the Yangmingtan Bridge, tilted to one side and crashed to the ground at 5:32 am, plunging four trucks to the pavement below, Huang Yusheng, a spokesman for the government of Harbin, Heilongjiang province, said at a news conference on Friday.

The collapsed ramp, some 100 meters in length, fell from a height of 30 meters, according to Xinhua News Agency.

Two people were killed on the spot, a third died later, and five remain in hospital, Huang said.

The four trucks appeared to be overloaded with stone and feed, Huang told reporters.

The bridge, part of an airport expressway in Harbin, opened in November after 18 months of construction, local media reported. The bridge was designed to handle up to 9,800 vehicles an hour.

Investigations are under way.

But Huang Yi, spokesman for the State Administration of Work Safety, China's top safety watchdog, said that there must be some quality problems with the bridge.

"We will urge local authorities to release the investigation results in a timely manner," he told a news conference in Beijing on Friday.

Eyewitnesses were shocked by the accident.

"I heard a deafening sound when I was washing my face," said a construction worker who only gave his surname as Wang. "The prefabricated house I was staying in shook like it was an earthquake."

Wang's fellow worker said he was piloting a crane with his back facing the bridge. "I turned back after hearing the thud and saw one truck had already crashed upside down on the ground and three others rolled over," said the man, who didn't give his name.

Among the injured, one is female, according to Sun Ran, deputy head of Harbin No 1 Hospital.

"Three people were seriously injured and they need immediate operations," she said.

Sun said the most seriously injured is Feng Licheng, a 41-year-old man whose liver was lacerated and vertebra broken and there are some wounds on his head.

"All the injured are out of life-threatening danger except Feng," Sun said.

It was at least the sixth major bridge collapse across the country since July last year and shoddy construction and overloading are to blame, according to Xinhua.

[nexus73]

In the USA, old bridges collapse.  In China new bridges do! 

Rick

[Alps]

So the span was long enough to have at least three vehicles on it (I saw photos of two rock trucks and another red one), and all three happened to be overloaded trucks. Clearly this scenario was not planned for - this is what factors of safety are for. My guess is that they designed to the maximum expected load rather than 2.5-3 times the maximum expected load. Doesn't help that the span was cantilevered with the lane all the way on the outside. If the lane had been on the inside with an outside shoulder, as is much more typical everywhere in the world, this may never have happened.

[cpzilliacus]

So the span was long enough to have at least three vehicles on it (I saw photos of two rock trucks and another red one), and all three happened to be overloaded trucks. Clearly this scenario was not planned for - this is what factors of safety are for. My guess is that they designed to the maximum expected load rather than 2.5-3 times the maximum expected load. Doesn't help that the span was cantilevered with the lane all the way on the outside. If the lane had been on the inside with an outside shoulder, as is much more typical everywhere in the world, this may never have happened.

No truck weight enforcement in China? 

On my job, I saw the Maryland Transportation Authority Police weigh a five-axle tractor-trailer combination on U.S. 50 just west of the Chesapeake Bay Bridge.  The truck tipped the scales at over 130,000 pounds (maximum without a permit on  most U.S. roads is 80,000 pounds for a five-axle combination).

The fine on the resulting ticket was massive (if I recall correctly, over $5,000), and the truck was detained until the company could get a second truck (and wheel loader - it was carrying wood scrap) to off-load the overloaded trailer down to legal weight (and the officers weighed again it before allowing it to leave).

[J N Winkler]

My interpretation of the pictures is a little different.  What I see is a flyover ramp with two lanes and no shoulder, the lanes being marked by shoulder stripes just in front of the crash barriers and by an unbroken lane stripe which presumably means changing lane on the ramp is not permitted, as shown in this overhead shot of the collapsed segment:



The uncollapsed segment in the background of this picture also suggests that the deck is more or less centered on the piers in a typical "hammerhead" configuration:



Journalism from China is so unspecific and generally unreliable that it is hard to get an impression of Chinese engineering standards and construction supervision.  I can remember reading, however, that Chinese highways are designed to a nominal maximum gross vehicle weight of about 60,000 lb, as opposed to the federal floor in the US of 80,000 lb with design maximum GVWR of up to 120,000 lb in states and on turnpikes which choose to cater to overweight vehicles.

Chinese engineers may very well use lesser factors of safety than most Western countries, but I doubt they omit them altogether.  I would be more inclined to suspect either defective materials or quality assurance problems in the design verification process.

[cpzilliacus]

The ramp of the brand-new Yangmingtan Bridge in china in the city of Harbin has collapsed, with 3 reported fatalities. Judging by news photos the section that collapsed appears to be a UCEB.

N.Y. Times: Collapse of New Bridge Underscores Worries About China Infrastructure

According to the official Xinhua news agency, the Yangmingtan Bridge was the sixth major bridge in China to collapse since July 2011. Chinese officials have tended to blame overloaded trucks for the collapses, and did so again on Friday.

Many in China have attributed the recent spate of bridge collapses to corruption, and online reaction to the latest collapse was scathing.

"Corrupt officials who do not die just continue to cause disaster after disaster,"  said one post on Friday on Sina Weibo, a Chinese microblogging service similar to Twitter.

[cpzilliacus]

The ramp of the brand-new Yangmingtan Bridge in china in the city of Harbin has collapsed, with 3 reported fatalities. Judging by news photos the section that collapsed appears to be a UCEB.

http://photos.mercurynews.com/2012/08/24/photos-bridge-collapse-in-china-kills-five-on-friday-august-24-2012/

There's reference in the above images to a "suspension" bridge, but those pictures don't look like a suspension bridge to me.

Any ideas (beyond the trucks being over on gross weight) about what might have failed? 

Note that I am not a bridge engineer, so what follows is speculative only!

It seems (from the images) that the bridge stringers are intact.

The bridge piers also seem to be intact.

Could the pier caps have been too small to carry the stringers and the load from an overweight truck?

Could a bearing have failed, setting off a "chain reaction" failure of some sort?

[J N Winkler]

There's reference in the above images to a "suspension" bridge, but those pictures don't look like a suspension bridge to me.

The ramp that collapsed feeds into an approach to the suspension bridge.  There is at least one photo (looking upstream of the collapsed roadway) which shows a suspension cable.

The New York Times is also, I am fairly sure, inaccurate to say that the collapsed ramp was 100 feet above ground.  The pictures suggest the true difference in level is closer to 25 feet; I think 100 feet is probably the navigational clearance of the suspended span itself, which is not involved in this collapse.

See what I mean about shoddy China-focused journalism?

Any ideas (beyond the trucks being over on gross weight) about what might have failed?

The press reporting I have seen indicates that this was a tilt failure--in other words, the deck tipped off the piers.  So:

Could the pier caps have been too small to carry the stringers and the load from an overweight truck?

Broadly speaking, I think this is the likeliest explanation.  If Chinese engineering standards are anything like those in Western countries, and there is no obvious reason to believe that the Chinese would embarrass themselves or undermine their ability to sell engineering services abroad by using standards which are conspicuously inferior to those used elsewhere, the ramp should have been designed to handle not just dead load, which includes not just the weight of the girders but also the deck, railing, lamp standards, etc., but also a live load corresponding to legally permitted loads plus an acceptable factor of safety to promote longevity of the bridge, allow safe movement of extralegal loads under permit, etc.

I don't think the ramp would have failed if it had actually been designed to the applicable standards.  The guess I favor is that it was erroneously designed and the mistake was not caught before construction because the design verification process was rushed.  This theory receives support but not confirmation from the fact that this bridge was apparently built as part of a 2009-2010 stimulus program in which major projects were rushed to construction regardless of whether they were genuinely "shovel-ready."  However, one other factor works against this explanation:  the ramp appears to use post-and-lintel construction with precast concrete girders of standardized dimensions and manufacturing tolerances.  It is usually harder to make mistakes with cookie-cutter designs such as this and the mistakes that do result are more likely to arise from a failure to see unusual, site-specific conditions that "break" the design.

Could a bearing have failed, setting off a "chain reaction" failure of some sort?

This is another possibility.  In the presence of a verified good design, this is usually a symptom of inferior materials (too much sand in concrete, that kind of thing).  However, I think it is less probable than the design-error theory, since the piers visible in the pictures all show what appear to be clean breaks.  If a concrete failure were implicated, I would expect to see half-crumbled concrete, twisted rebar, etc. but there is remarkably little of that.

[cpzilliacus]

There's reference in the above images to a "suspension" bridge, but those pictures don't look like a suspension bridge to me.

The ramp that collapsed feeds into an approach to the suspension bridge.  There is at least one photo (looking upstream of the collapsed roadway) which shows a suspension cable.

Thanks for pointing that out.

The New York Times is also, I am fairly sure, inaccurate to say that the collapsed ramp was 100 feet above ground.  The pictures suggest the true difference in level is closer to 25 feet; I think 100 feet is probably the navigational clearance of the suspended span itself, which is not involved in this collapse.

See what I mean about shoddy China-focused journalism?

I do indeed.

Any ideas (beyond the trucks being over on gross weight) about what might have failed?

The press reporting I have seen indicates that this was a tilt failure--in other words, the deck tipped off the piers.  So:

Could the pier caps have been too small to carry the stringers and the load from an overweight truck?

Broadly speaking, I think this is the likeliest explanation.  If Chinese engineering standards are anything like those in Western countries, and there is no obvious reason to believe that the Chinese would embarrass themselves or undermine their ability to sell engineering services abroad by using standards which are conspicuously inferior to those used elsewhere, the ramp should have been designed to handle not just dead load, which includes not just the weight of the girders but also the deck, railing, lamp standards, etc., but also a live load corresponding to legally permitted loads plus an acceptable factor of safety to promote longevity of the bridge, allow safe movement of extralegal loads under permit, etc.

The trucks that fell off the bridge when it failed look to have been hauling huge loads of some sort of aggregate or perhaps finely crushed stone.  In tall dump trailers like that, these would (I assert) have been illegal (as in illegally heavy) loads in most U.S. states, though I also think that bridges in the U.S. and Canada and the EU tend to be sufficiently over-designed that they would not have collapsed with two such loads.

I don't think the ramp would have failed if it had actually been designed to the applicable standards.  The guess I favor is that it was erroneously designed and the mistake was not caught before construction because the design verification process was rushed.  This theory receives support but not confirmation from the fact that this bridge was apparently built as part of a 2009-2010 stimulus program in which major projects were rushed to construction regardless of whether they were genuinely "shovel-ready."  However, one other factor works against this explanation:  the ramp appears to use post-and-lintel construction with precast concrete girders of standardized dimensions and manufacturing tolerances.  It is usually harder to make mistakes with cookie-cutter designs such as this and the mistakes that do result are more likely to arise from a failure to see unusual, site-specific conditions that "break" the design.

I think this is correct, and we should praise "cookie-cutter" design, at least when it comes to "regular" highway bridges (large, long-span bridges are a different story).  On the "Contract A" section of Maryland's ICC, due to an error by the engineers that designed the bridges, the pier caps did not contain enough rebar (or maybe the rebar was in the "wrong places" of the caps).  This was discovered when state inspectors noticed very small cracks in the caps. The design/build team is now having to retrofit more steel into the pier caps at no additional expense to MdTA.

Could a bearing have failed, setting off a "chain reaction" failure of some sort?

This is another possibility.  In the presence of a verified good design, this is usually a symptom of inferior materials (too much sand in concrete, that kind of thing).  However, I think it is less probable than the design-error theory, since the piers visible in the pictures all show what appear to be clean breaks.  If a concrete failure were implicated, I would expect to see half-crumbled concrete, twisted rebar, etc. but there is remarkably little of that.

Am I wrong about the materials that go into bearings?  I thought they were usually made of steel, not concrete, because steel "moves" better as the bridge expands and contracts.

[agentsteel53]

The truck tipped the scales at over 130,000 pounds (maximum without a permit on  most U.S. roads is 80,000 pounds for a five-axle combination).

The fine on the resulting ticket was massive (if I recall correctly, over $5,000)

10 cents a pound, multiplied by the probability of getting pulled over...

that may just be a cost/benefit calculation that the trucking company figured was acceptable.

$5000 is not a massive fine for that egregious a violation.  someone should've seen jail time for that.

[cpzilliacus]

The truck tipped the scales at over 130,000 pounds (maximum without a permit on  most U.S. roads is 80,000 pounds for a five-axle combination).

The fine on the resulting ticket was massive (if I recall correctly, over $5,000)

10 cents a pound, multiplied by the probability of getting pulled over...

that may just be a cost/benefit calculation that the trucking company figured was acceptable.

$5000 is not a massive fine for that egregious a violation.  someone should've seen jail time for that.

No dispute at all, though in Maryland, the per-pound rate of fine "ramps up" as the amount over the legal limit increases. In addition, the driver of an overweight load can also be charged with "Person failing to obtain and possess required permit before moving an (oversized, overweight) load according" to TA § 24 112 e2 (fine $1,010). 

The per-pound penalty for that overweight load is also a little higher now, at $0.80 per pound for crossing (or attempting to cross) that bridge, per TA § 27 105.  I think the special, extra-high fines for crossing that bridge overweight were recently added.

[Mr_Northside]

On my job, I saw the Maryland Transportation Authority Police weigh a five-axle tractor-trailer combination on U.S. 50 just west of the Chesapeake Bay Bridge.  The truck tipped the scales at over 130,000 pounds (maximum without a permit on  most U.S. roads is 80,000 pounds for a five-axle combination).

As an asides to the topic at hand, I always thought it seemed goofy for that weigh station located AFTER crossing the massive bridge. I'm sure there's a reason for it not being BEFORE the bridge, probably land availability or something.

[cpzilliacus]

On my job, I saw the Maryland Transportation Authority Police weigh a five-axle tractor-trailer combination on U.S. 50 just west of the Chesapeake Bay Bridge.  The truck tipped the scales at over 130,000 pounds (maximum without a permit on  most U.S. roads is 80,000 pounds for a five-axle combination).

As an asides to the topic at hand, I always thought it seemed goofy for that weigh station located AFTER crossing the massive bridge. I'm sure there's a reason for it not being BEFORE the bridge, probably land availability or something.

It's after because the MdTA was trying to save money by putting in a small truck scale that only weighs one axle (or tandem) at a time.  The design assumption was that trucks would get waved-over after they paid the toll (this was when there was a westbound toll). 

Eastbound, that's how it works even now.  Trucks paying with E-ZPass must use one of the right four lanes, and may not use the lefthand E-ZPass only lane.

There have been discussions about building a weigh/inspection station on the westbound approach between the Md. 8 interchange and the foot of the bridge (in other words, on the east side of the crossing, for westbound trucks), but nothing so far.

[Brandon]

It was stamped "Made In China".  That, to me, explains more about why it fell that almost anything else.  It's a label I try to avoid, especially on tools and other such more expensive items as I've found such things tend to fall apart faster than if they're made anywhere else (US, Mexico, Vietnam, etc).  It's almost as if they slap something together and just don't care about longevity.

[Duke87]

Yes, but they can rebuild it ten times for cheaper than we can build it once! So who cares? They save money!

[707]

As bad as that is, it could be worse. At least it wasn't a repeat of the I-35W bridge collapse.