Alton Towers Smiler crash: How safe are rollercoasters?

The Smiler is the world's first 14-loop rollercoaster and opened two years ago

Four people have been seriously hurt in a rollercoaster crash at Alton Towers. How safe is it to ride rollercoasters? And were there any warning signs before this accident?

Rollercoaster enthusiast Ian Bell, who owns and manages a fan group for rollercoasters, CoasterForce, said serious accidents involving them were incredibly rare.

Most deaths at amusement parks are through ill-health, he said, such as from heart attacks.

"I always say you are more likely to be involved in a serious crash driving to the theme park than at the park," said Mr Bell.

"There are only a handful of accidents every year, spread out all over the world."

However, Mr Bell said The Smiler at Alton Towers has had "quite a chequered past" which is "quite a rarity for a theme park as well known as Alton Towers".

He has ridden it several times and described it as "good fun" but a "very disorientating" experience.

The ride is the world's first 14-loop rollercoaster and Mr Bell said it is "a bit of a prototype".

"Not everything, unfortunately, was right first time," he said.

Four people were seriously injured and 12 others had less serious injuries

The £18m ride has only been operating for two years and there were problems even before it opened in May 2013.

A group of 16 journalists were left dangling on it at a steep angle as they tried it out on a preview night.

Then, in July 2013, 48 people had to be rescued after a piece fell off the track.

It closed again just a few weeks later, in August 2013, due to a "technical issue".

There have been several problems with The Smiler since it opened two years ago

In November 2013 some wheels fell off and hit four people in the front carriage.

Kevin Hayes-Heath, who was hit on the shoulder, said the incident was "pretty frightening".

"We were shouting at them to stop the ride because they were about to send another party off," said Mr Hayes-Heath.

The ride was closed for five days while an investigation was carried out.

When it reopened, an Alton Towers spokeswoman said it had been "working with the designers to review and replace all of the elements connected to this part of the ride".

"We remain committed to ensuring that all of our rides meet the highest standards in all areas," she added.

But then, in April 2014, riders were left stranded in the air when the ride ground to a halt at the top of a near vertical section.

Rollercoater enthusiast Ian Bell has ridden The Smiler several times

It was made by a German company called Gerstlauer, which also built the trains for a rollercoaster in Six Flags Park in Texas from which a woman fell to her death in 2013.

The firm has not yet commented on the incident.

Mr Bell said he did not know what had caused the crash but it seemed an empty car had gone to a low part of the track, and then a car containing riders had come round and crashed into it.

On this particular ride the operator sits inside a building, meaning he or she cannot see if the track is clear with their own eyes, he said.

Instead, the operator relies on a computer control panel to see where the cars are.

A woman fell to her death from a rollercoaster train in Texas, built by the same company as The Smiler

Ian Crabbe, Alton Towers divisional director, has said it is investigating the incident in conjunction with representatives of the Health and Safety Executive.

"For an accident like this to happen does surprise me because they are a reputable company and they have got a lot of technology to prevent this happening," added Mr Bell.

"It's one of the best rides in the UK and it's a shame to see it in the headlines today for all the wrong reasons."