Timeline of problems on The Smiler at Alton Towers

Today's serious crash injuring 16 passengers on The Smiler roller coaster at Alton Towers is the worst incident the ride has had to date.

It has had a series of problems since it opened in 2013. Here is a timeline of problems in its inaugural year.

• Wednesday April 24: Work is completed on the Smiler. Described by the resort as 'the most impressive addition to Alton Towers', it cost £18million and required 700 tonnes of steel.

• Thursday May 23: The opening of the Smiler was delayed due to technical problems described by the park as 'unforeseen teething problems'.

• Tuesday May 28: The Smiler is still closed, with the park unable to say when it will open.

• Saturday June 1: The world's largest roller-coaster finally opens at Alton Towers.

• Tuesday July 23: The ride is forced to close after reports of a bolt falling from the ride.

• Wednesday July 24: The Smiler re-opens, with a park spokesperson claiming that at no point was anyone in danger.

• Saturday November 2: The roller-coaster is againforced to close after some of its wheels came off while at the highest point of the ride.