A trucker who crashed into a motorway footbridge, causing £1.5 million of damage, has avoided jail after admitting causing serious injury by dangerous driving.

Alan Austen, 64, was arrested after 170 tonnes of concrete came crashing down onto the London-bound carriageway of the M20 during a Bank Holiday when the route was being used by many drivers.

Austen, of Jedburgh Drive, Darlington, County Durham, had previously denied the charge, as well as dangerous driving, and was due to stand trial at Maidstone Crown Court in February.

The crash happened at junction four for Leybourne on August 27, 2016.

Motorcyclist Jim Shaw, 73, suffered minor injuries after skidding sideways at 70mph to try to avoid the falling debris.

Concrete from the bridge also crushed two lorries - a Hitachi excavator and a lorry and trailer, both worth about £150,000.

The incident prompted a major operation involving dozens of police officers, firefighters and paramedics.

Austen entered the plea at Maidstone Crown Court this afternoon.

Judge Philip Statman said: "It seems quite remarkable that there was not a major pile up of vehicles occurring behind from the bridge falling down.

"It is remarkable no one lost their lives as a result."

Prosecutor Peter Forbes said before Austen set off with heavy plant on the trailer colleagues expressed concern about the height but he assured them it was fine.

The tip of the arm of an excavator on the trailer struck the bridge while the lorry was travelling at 21mph, bringing it down.

Austen admitted at the scene: "I fouled up."

Mr Shaw suffered displaced fractures of his ribs. He told in an impact statement how he feared he would be killed and added he would never recover from the ordeal.

Mr Forbes said Austen was working for a company moving plant from one site to another from one side of the M20 to the other.

He was to drive to the next junction and return on the opposite carriageway. On the trailer was a dumper truck and an excavator.

"He didn't measure the height of the load and ignored concerns raised by two colleagues who raised questions about the height," said Mr Forbes.

"He assured them it was fine. The load was too high to be transported safely on a road which involved passing under several bridges.

"The defendant's driving was dangerous from leaving the site to the point of impact, a distance of about two miles."

As Austen passed under one bridge there was a puff of dust. He checked his tyres and used a measuring stick to check the height.

He thought he might have had a puncture as there was a loud bang.

Mr Forbes said the inference was that the load had clipped the bridge. The collision occurred at the next bridge.

The arm of the excavator caused the bridge to fall straight down. It landed on the Austen’s load, crushing the dumper truck and striking a passing lorry.

Mr Shaw saw the bridge collapsing and slid his motorbike to avoid the concrete which now covered the carriageway. He was taken to hospital and treated for his injuries.

Austen had claimed when he took measurements after hearing a loud bang it was 16ft 2in, but then acknowledged it could not have been and accepted it must have been too high.

The driver of the HGV that was passing Austen’s truck at the time was left in shock.

Mr Forbes said the damage and disruption was considerable. The road was closed in both directions.

The East Street footbridge, he said, had not been replaced, but was to be “renewed”.

Austen was sentenced to 12 months suspended for two years with 200 hours unpaid work.

David Skelton from the Crown Prosecution Service said: "It was our case that it would have been obvious to a competent and careful driver that the load was too high to be transported safely under the bridge.

"The defendant had supervised the loading of the items and did not measure the height before setting off, ignoring concerns raised by two colleagues.

"He stopped just prior to the crash to check his load, but this was obviously inadequate.

"His actions led to the bridge collapse, which left one man with serious injuries and which had a huge financial impact on the whole region, closing off a vital transport link in the South East during a busy travel period.

"It was fortunate that no-one was killed and more people were not hurt in this incident, which could have been much more serious."

Speaking to reporters outside, Austen said he was happy to be leaving court a free man.

He said: "I regret what happened on the day and what has happened today.

"I feel seriously sorry for him [Mr Shaw], I wish it hadn't happened but it did and I can't do anything about that."

Judge Statman said he believed Mr Shaw’s injuries were restricted by the great skill he showed as a motorcyclist, sliding away from the falling debris.

“That, in my judgement, was responsible at the end of the day for saving him,” he said.

“He has suffered considerably as a result of his injuries.”

The judge said Austen was a highly experienced HGV driver without any convictions and it would have been obvious to him the lorry in its loaded state was dangerous.

Austen, he said, had a gut feeling something was wrong when he stopped after passing under a previous bridge.

The bridge he wrecked had a minimum height of 5.17m (17ft) for clearance.

The cost of damage included Austen’s lorry written off at a £30,000 cost, £130,000 damage to another nearby truck and the demolition of the bridge.

The inconvenience caused to the community by the road being closed for several days was “profound”.

“The risk of harm to other road users was considerable,” said Judge Statman.

“Miraculously, the physical harm to other road users was restricted to Mr Shaw.”

Austen was a carer for his sister who has mobility problems and sat in court in a wheelchair.

“You are her rock,” said the judge.

“You have shown genuine remorse for that which you have done. When asked about this by the police you summed it up by saying ‘I fouled up.’ How right you were.”

Ian Bridge, defending, said the most important thing for Austen to state was that he was sorry.

“He is soon to retire - 40-plus years of loyal service driving vehicles,” he said. “Right at the end of his career he is ashamed to say he is involved in this incident.

“When he looks back on it he is embarrassed and ashamed about the arrogance to his colleagues, because he didn’t believe the load was too high. He assumed it was alright.

“When he stopped and took a measurement he didn’t do it properly. He is very sorry, he is ashamed and he is very embarrassed about what happened.

“It has brought a tragic end to an otherwise exemplary career. He has driven all over the world. He has driven millions of miles, and yet this shame hangs over him.”

The maximum sentence for the offence is five years imprisonment.