Hong Kong’s Mass Transit Railway tells passengers not to bring “dangerous or flammable goods or metallic balloons” into station areas and on trains. But what possible harm can a seemingly innocent balloon bring?
Back in 1996 a balloon managed to shut down an entire railway line, as the South China Morning Post writes:
Rush-hour chaos may foil balloons on MTR
Friday, 01 March, 1996
By John Flint and and Michelle Chin
Children’s foil balloons may be outlawed in MTR stations after a rogue Minnie Mouse balloon floated into a tunnel and brought rush-hour traffic to a halt.
About 100,000 commuters were forced to wait in stations on the Island line after the helium-filled balloon tripped an electric current and burned through an overhead cable.
The incident happened at 6.46 am in Causeway Bay, bringing all trains between Admiralty and Quarry Bay to a standstill for 11/2 hours.
The Mass Transit Railway Corporation said it was considering a ban on the balloons particularly during festivals.
But that would force the company to hire security guards to take the balloons from children, it conceded.
Operations director Bill Donald said the corporation did not want a reputation as a kill-joy and would try to find a practical compromise.
He said runaway balloons caused hundreds of stoppages each year, including 10 during Lunar New Year. Yesterday’s was the only balloon to sever a power line, creating chaos and forcing emergency repairs.
Power is normally restored within minutes of a cable being short-circuited by a stray balloon – but MTR investigators suspect the latest culprit had an unusually tough skin.
‘Normally the balloons would be burned up by the overhead cables,’ Mr Donald said.
The investigation will examine whether metallic balloons are being made more durable.
Over in Sweden they have had similar incidents:
Helium balloon stops Malmö tunnel train
August 1, 2011
Passengers were left waiting for two hours before being evacuated from a Denmark-bound train on Sunday after a helium balloon caused a power outage in Malmö’s city tunnel.
Some 97 passengers were left sitting on the SJ X2000 train bound for Odense in Denmark on Sunday evening as technicians worked to solve the problem, after smoke was detected in the tunnel.
The source of the smoke was traced to a power outage caused by an errant helium balloon complete with a long ribbon which had got itself entangled in some power lines.
As has Melbourne, where a single balloon took out four railway lines:
Troubles balloon on the City Loop
November 29, 2012
By Adam Carey
Train chaos is easing after Metro removed the balloons that were caught in overhead wires between Flinders Street and Southern Cross stations, temporarily stalling four railway lines.
And finally – Sydney has joined the party:
Inside the train chaos and how a balloon shut parts of the system down
August 18, 2018
A balloon is being partially blamed for contributing to Sydney’s transport chaos as the Transport Minister sought to explain what exactly unfolded on Friday night and Saturday that led to passengers being stuck on trains between stations and major delays across the network.
I wonder if helium balloons might even be a waste of a valuable lifting gas. If we didn’t allow helium balloons, more of it would be available for filling airships.
Helium is an element that is rare on Earth, due to it being able to escape gravity and leak away into space:
Other than lifting gas, semiconductor manufacturing and MRI machines also need helium, which is leading to a shortage: