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Gondola accident at Ngong Ping 360


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#1 SkiBachelor

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Posted 12 June 2007 - 01:10 PM

Completed last year, the Ngong Ping 360 gondola built by Leitner had a cabin plunge 50 meters to the ground Monday, June 11th, 2007 after it mysteriously detached while passing over a tower during non attraction hours. Investigators have found that 10 sheaves had been extremely damaged of where the cabin feel. Investigators are trying to figure out how these sheaves got damaged and if they contributed to the accident.

From an inside source, it appears that SkyRail boosted the gondola's hourly capacity during peak periods by running it at 7 m/s, instead of its designed speed of 5 m/s. No warning alarms went off when the cabin detached from the haul rope at the tower, but clanking noises were heard shortly after the incident occurred.

http://www.thestandard.com.hk/news_detail....&con_type=3

UPDATE:

Quote

He said the horizontal beam on the cable car may be too thin, and unable to handle passenger weight and wind velocity. "The plunge could have been caused by the snapping of the beam."

http://www.thestandard.com.hk/news_detail....&con_type=1

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#2 Peter

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Posted 22 June 2007 - 10:11 PM

And the plot thickens...
The random speculation by the University of Hong Kong is ridiculous, but I find it interesting that Doppelmayr withdrew their bid for the project because they did not think a 2 cable system would withstand the weather. The USD $125 million ride is closed indefinately. What a mess.


Human error could be to blame for Hong Kong cable car's plunge


Hong Kong - Human error may be to blame for a cable car cabin plunging 50 metres to the ground in Hong Kong, engineering experts said Wednesday. The cabin, capable of carrying up to 17 people, was empty when it broke free and fell the equivalent of 13 storeys from its cable on the Ngong Ping 360 tourist ride on Lantau Monday evening.

The accident took place during a test run at 8 pm, an hour after the 5.7 kilometre ride that takes people hundreds of metres above sea and steep hillsides to the Big Buddha statue at the top of the island, had closed.

The ride was closed indefinitely Tuesday pending an investigation which will include experts from overseas.

University of Hong Kong professor of engineering Soh Ai-kah said he believed the most probable cause was human error and that the car had not been re-attached to the cable properly after an annual inspection last week.

Lo Kwok-keung, of the Polytechnic Univeristy's department of mechanical engineering, who carried out a visit of the site following the accident, agreed.

"I believe the workers failed to tighten the screws well and they did not check them," he told local media. "After a few days, the screws loosened more and failed to hold the cabin when it swung."

Meanwhile, it emerged that a company had withdrawn its bid to build the cable car because it did not think the two-wire cable system which was chosen for the ride, was suitable given the length of the journey.

In documents quoted by the South China Morning Post which were sent to the MTR Corporation in 2002, Austrian company Doppelmayr said a three-cable system was more suitable.

"The risk of operational failure as well as the efforts required for a restart following a shutdown in gusty or even hurricane-like winds are much higher than compared with a tri-cable system," Doppelmayr wrote.

The accident is the most serious setback for the 125-million-US dollar attraction, which has been dogged by a series of mishaps which began even before it opened last September.

Technical problems delayed its original opening for two months and were followed after its opening by a number of incidents on the cable car ride in which passengers have been stranded for up to two hours by mechanical problems.

Bill Calderwood, chief executive of Skyrail, which operates the Ngong Ping 360 cable car service, said his company was "very concerned" and had launched its own investigation to run in conjunction with the government investigation.

Accidents involving cable car cabins falling from the cables that carry them are rare but the tourist industry leaders in Hong Kong fear the accident will affect people's confidence in the ride.

In 1976, a steel cable snapped on a cable car at the ski resort of Cavalese, Italy, killing 42 people including 15 children.

This post has been edited by Skier: 22 June 2007 - 10:20 PM

- Peter<br />
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#3 Peter

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Posted 23 June 2007 - 01:19 PM

Here are some pictures.

Attached File(s)


- Peter<br />
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#4 Peter

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Posted 23 June 2007 - 01:22 PM

Does anyone think that if the bicable setup is found to be insufficient that Leitner will have to refund the $125 million? Could that put them out of business? Looking at the spans of this thing and reading Doppelmayr's writing it certainly seems like it should have been a 3S.

More pictures:

Attached File(s)


- Peter<br />
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#5 Peter

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Posted 23 June 2007 - 08:09 PM

Skyrail firm told to fire staff if liable for accident


Skyrail-ITM - the Australian firm behind the Ngong Ping 360 cable car system on Lantau - will be asked to replace its entire management team if it is found to be responsible for the incident Monday in which a cabin plunged 50 meters to the ground after becoming detached from the cable.
The warning came from Secretary for Economic Development and Labour Stephen Ip Shu-kwan Tuesday as he announced a thorough investigation will be launched with the help of overseas experts.

The probe is expected to be completed within a month.

The incident was the first of its kind at the Lantau tourist attraction since the trouble-plagued cable car system began operation in September last year.

Ip said the investigation will cover not only the mishap itself, but also the overall management and maintenance of the system.

"If it turns out to be a management problem, we'll ask MTR Corp [which owns and operates the project] to do what it needs to do."

He said that, according to the Aerial Ropeways (Safety) Ordinance, the director of the Electrical and Mechanical Services Department is empowered to request the corporation to have a management team that is capable of handling the skyrail system.

"We're taking safety as our top priority. Unless and until the director is satisfied with the safety of the system, we'll not allow the service to resume," Ip said.

Cable car services at Tung Chung - which is linked to the famous Big Buddha by the system - have been ordered to be suspended
indefinitely until it can be established what went wrong.

No one was injured in Monday evening's incident in which the empty cable car crashed to the ground during a test run after operating hours.

Immediately after the crash, maintenance staff members were sent to each of the system's supporting towers to examine if other cabins had plunged along the whole ropeway.

Investigators found some 10 gear wheels had been seriously damaged on the system where the cable car plunged.

The gear wheels, installed on the towers, are used to hook cable cars in place as they pass the towers.

Investigators are still trying to find out how these gears were damaged and whether the damage was related to the crash.

An inside source revealed to The Standard Tuesday the mishap was associated with a decision by Skyrail- ITM's senior management to boost passenger capacity during peak periods.

According to the source, it was the first time Skyrail had tried to push the motors of the "circulating bi-cable aerial ropeway" system to the fullest and unprecedented speed of seven meters per second. "The system has always been tested on five meters per second even at its initial trial runs. It's a senior management decision to test the system's fullest operational speed and its emergency braking.

"With a nearly 30-40 percent speed enhancement, the journey time could, therefore, be shortened, enabling a faster circulation of cabins. At least 3,000 to 4,000 extra passengers a day could be carried," the source said.

Currently, the highest passenger load recorded is about 11,000 per day. According to Skyrail, the system's maximum load can be boosted to 3,500 passengers an hour. The whole ropeway circulates 109 cabins at an average speed of four to five meters per second.

It takes 20 to 25 minutes to finish the 5.7-kilometer journey from Tung Chung to Ngong Ping.

According to an international expert from the world's largest ropeway construction company, operating on seven meters per second is "not common," and he was shocked to hear of the accident. "Bi-cable aerial ropeway is what we call one of the pioneering ropeways.

"Such an installation is not so common around the world," said Christoph Hinteregger, technical director at Austria-based Doppelmayr Seilbahnen.

"There aren't many models that can successfully run at seven meters per second, operators of bi-cable aerial ropeway still need to gather more experience," he told The Standard by phone from Switzerland.

Hinteregger said while "the maximum speed of a circulating bi-cable aerial ropeway is not theoretically unachievable," it can depend other factors like weather conditions such as wind and smog.


A spokesman for Skyrail-ITM refused to comment on whether the system was running at seven meters per second under an "ongoing review."

However, the spokesman admitted that an increased speed would help boost passenger load and the company is promoting Ngong Ping 360 in other countries.

The spokesman also denied there was any relationship between enhanced speed and passenger capacity.

After a three-day annual review was performed in early June to adjust ropeway tension, Leitner Ropeways programmers were adjusting a monitoring system called the Scada System, the source said.

The system is designed to monitor various functions during operations, including distance between cabins, motors, cabin doors and wind speed.

A fault message would be sent out and the system halted should the monitoring system detect any abnormalities, the source said.

But it was discovered a few hours before Monday's accident that a door on a cabin departing Ngong Ping for Tung Chung failed to close tightly, leaving a space of "two to three fingers."

"It was Monday afternoon, right before the accident took place, but the monitoring system didn't send out any alarm message. The cabin kept on operating," the source said.

The company performed emergency braking while the cable cars were operating at the maximum speed of seven meters per second, when suddenly "ka ka" noises were heard. Right after that, a fault alarm was raised, suggesting there had been problems in Tower 2B.

A Skyrail statement said an engineering team had been investigating since Monday night.

The Legislative Council will hold a special meeting of its economic panel Friday to discuss the incident.
- Peter<br />
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