The family and colleagues of a bus driver who was sentenced to more than five years' jail after crashing into Melbourne's Montague Street bridge, injuring six people, have returned to the scene to protest his sentence.

Key points: A petition in support of Jack Aston has been signed by more than 4,000 people

A petition in support of Jack Aston has been signed by more than 4,000 people In sentencing, Judge Bill Stuart said he was "astonished" Aston did not see the Montague Street bridge

In sentencing, Judge Bill Stuart said he was "astonished" Aston did not see the Montague Street bridge Six passengers were seriously injured when the bus crashed into the bridge, but no one died

Jack Aston, 55, was driving for Gold Bus Ballarat on February 22, 2016, when the front of the 3.8-metre-high bus struck the base of the bridge, which has a three-metre clearance.

In October a jury found him guilty of six charges of negligently causing serious injury, and on Monday he was jailed for five years and three months, with a non-parole period of two-and-a-half years.

The company Aston worked for, Gold Bus, ferried family, friends and supporters from Ballarat to Melbourne on Sunday morning, holding up placards in support of Aston and accusing the courts of "victimising" him.

Aston's daughter Meg Aston said the support for her father had been amazing.

"It shows a lot people out there think it's unfair what's happened and it makes us feel a bit better at the end of the day that we have a lot of support with us as well," Ms Aston said.

"It makes things a little bit easier.

"I think that's why it hit so hard for us; we know he did everything he could, and how cautious he was. He dedicated a lot of his life to his job."

The charter bus was unable to clear the bridge, which was only three metres high. ( ABC News: Simon Winter )

Aston's former colleagues at Gold Bus said the stress of the crash and then the court case had sent their friend grey.

Thomas Van Der Linden described Aston as a "good bloke" and undeserving of such a tough penalty.

"He's a model citizen who seems to have been victimised through the courts," he said.

"This is a guy who all he did was to do his job, and things happened, and now he's been victimised for it."

Driver was 'concentrating on passengers'

A plea hearing earlier this month heard Aston was an experienced driver, but was "confused" and had failed to see numerous warning signs over a 300-metre stretch of road on the day.

Six passengers were injured in the crash. ( Twitter: Metropolitan Fire Brigade )

Aston had dropped off passengers at the Melbourne Convention and Exhibition Centre and was taking others to a hotel on St Kilda Road when the crash occurred.

Gold Bus founder Donald McKenzie also told the plea hearing that Aston had been "let down by the company" as it did not warn him of the driving conditions in the area.

"I'd like to apologise on behalf of the company to the six passengers who were injured," Mr McKenzie said.

"I'd also like to apologise to Jack and his family who have been put through the mill."

But in sentencing, Judge Bill Stuart said employers could not be blamed for the "obvious failings" of their employees.

A sign ahead of the Montague Bridge directs high vehicle drivers to a detour. ( ABC News: Danielle Bonica )

"Three of your passengers saw the bridge. How it is that you did not is astonishing," he told Aston during sentencing.

"Why you were so grossly inattentive is unknown to me.

"Driving an 11-tonne bus with 14 passengers and failing to observe any of the warnings … is itself in my view a serious example of this offending."

The court also heard there was a sticker on the driver's instrument panel indicating the height of the bus, and the judge pointed out that one of the warning signs along the route was a height sensor which triggered red flashing warning lights.

A few months after the accident, VicRoads installed rubber flaps on an overhead gantry to warn drivers of the bridge's low clearance.

Speaking at the rally, Mr Aston's wife Wendy Aston said those who knew her husband knew how careful he usually was.

"He isn't careless," she said. "It's just him, I believe, concentrating on those passengers in the bus to get them to where they need to go. He was thinking about them."

She said an appeal against Aston's sentence was being organised and had to be submitted in January.

She said it was hard to picture what justice for her husband would look like, but was thankful for the backing of both her husband's employer and fellow bus drivers.

"I'm just doing one day at a time, it's hard," she said.

Aston's wife and daughter said they hoped to be reunited with him on Christmas day.

"We talk to him every day, we sang Happy Birthday to him over the phone to him yesterday," Wendy Aston said.

"He's trying to put a brave voice on for everybody, but I know he's doing it hard.

"He's a very active person, but I know he'd be doing it hard."

VicRoads installed an overhead height warning system at the bridge after the incident. ( ABC News: Danielle Bonica )

Supporters of Aston have also launched a petition addressed to Victorian Premier Daniel Andrews, calling for "justice", saying he accidentally hit the bridge but did not "break in to anyone's home or steal anything.

"People [convicted of] home invasion and assault get less than jacks (sic) sentence," the petition reads.

More than 4,000 people had signed the petition in the three days since it was launched on Friday.