Image caption A truck is immobilised until essential repairs are carried out

About 10,000 haulage operators are on a "red list" because of the risk they pose to other road users, the body that enforces lorry safety in Britain says.

The list represents one in eight transport firms, and is used by the Driver and Vehicle Standards Agency to target enforcement.

The hauliers are failing to ensure adequate maintenance and safety, or to monitor drivers' hours, the DVSA says.

But it said sanctions for repeatedly flouting the rules are inadequate.

DVSA chief executive Gareth Llewellyn told the BBC the regulatory system was "ripe for review".

Transport firms with vehicles weighing 3.5 tonnes or more need an operator licence, which carries obligations to ensure vehicles are roadworthy, safely operated and regularly inspected.

The DVSA enforces the regulations through roadside spot checks.

In 2015/16, just over 29,000 HGVs were checked at the roadside or at operators' premises, and nearly 9,000 were served with prohibition notices.

Impound vehicles

Depending on the severity of the defect, a vehicle is immobilised until repaired or the operator is given a deadline to get it fixed.

The agency scores operators on the likelihood their vehicles will be operating safely, with a green, amber or red rating.

Mr Llewellyn said: "Where we believe there is something of imminent impact for the public, we will impound that vehicle - it is about making sure those things that are really posing a risk to the public are taken out very quickly."

But Chris Snelling, of the Freight Transport Association, said the red list in itself was not an indicator of the industry's safety record, but of the capability of the DVSA to undertake enforcement.

He said if safety standards across the industry rose, he would anticipate the DVSA would still maintain a red list of 10,000 lower-performing operators.

Four killed in Bath

Image copyright PA Image caption The judge said the failures regarding the brakes on the 32-tonne tipper truck were "inexplicable"

In February 2015, the brakes of a tipper truck failed on a steep hill in Bath. The vehicle careered out of control and killed four people.

The investigation into Grittenham Haulage revealed inadequate mechanical checks and disregard for the rules around drivers' hours.

Just over a year before the crash, company boss Matthew Gordon had applied to the traffic commissioner in Bristol for an operator licence.

He got the licence but only after promising to introduce regular, independent checks on his drivers' hours, but he reneged on the pledge.

The traffic commissioner admitted that no-one checked up on Mr Gordon and that it is taken on trust that operators will honour their promises.

Sian Vaughan, who lost her husband Stephen in the accident, says that amounts to a missed opportunity to uncover the bad practice at Grittenham Haulage.

"I do believe there could have been a lot more done in respect to these regulating bodies…. they could have gone in there and the story could have been so different."

Two jailed over fatal Bath truck crash

Bath tipper truck firm loses licence

Hauliers running HGVs who are involved in serious or repeated breaches of their licence conditions are referred to traffic commissioners, who can suspend or revoke a licence and disqualify the directors of the company from seeking a new one.

Transport for London is funding roadside checks specifically targeted at hauliers they suspect of dangerous practices.

Over the last two years about 18,000 have been stopped. Only one in five complied with safety rules.

Image caption A roadside safety check in central London

Siwan Hayward, head of roads policing for TfL, said: "What is shocking is the difficulty in actually removing those rogue operators.

"We have been immobilising their vehicles, arresting their drivers, taking them through the criminal justice system and ultimately take them in front of the traffic commissioner so their operator's licence can be removed."

But a number of them defy the ban and stay on the road.

'Target the worst'

Ms Hayward said the sanctions to deal with this "small but persistent" group are inadequate - a point shared by Mr Llewellyn.

Mr Llewellyn added: "If you are serially non-compliant and operate vehicles that routinely put the public at risk, there's a great likelihood that you will not go to jail and I do not think that is correct."

The Freight Transport Association conceded there were "too many" haulage operators who did not comply with the safety regulations.

Mr Snelling said: "We would support more enforcement, as long as it continues to be effectively targeted against the worst HGV operators.

"Along with this we would support any efforts to improve the effectiveness of the punishments against these operators - if you are clearly not trying to be safe on the road, you should not be able to start work again under a new name."

A Department for Transport spokesperson said: "Britain has some of the safest roads in the world and DVSA conducts 250,000 roadside checks each year.

"Safety is our top priority and we are introducing more penalties for lorry drivers who exceed the maximum number of hours. We continue to keep the regulations around lorry safety under constant review."

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