Truck drivers are resorting to cocaine, speed and ecstasy to help keep themselves awake on long journeys.
Drug testing firms say to have 10% of drivers in an haulage firm test positive for drugs was "not unusual".
Road safety minister Mike Penning insists Britain's roads are among the safest in the world.
One lorry driver speaking to the BBC's5 live Investigatesprogramme, who works for a major international haulage company, claims he regularly sees drivers use ecstasy, cannabis, speed and cocaine to relieve the boredom of lengthy shifts.
The highly experienced driver has tried to raise the issue with managers at his firm but says nobody wants to take responsibility and tries to pass the buck to another department.
The driver, who spoke anonymously, says fellow drivers have in the past veered off motorways or overturned, and in some instances were not even able to remember the incident afterwards.
In one incident the insider was told about, a heavily drugged-up driver ploughed into workmen's vehicles by the side of a motorway.
When questioned by the police the driver was only tested for alcohol and he was not arrested.
"They are basically taking a recreational drug like ecstasy and speed to keep themselves awake because of the distances involved and because boredom just kicks in," said the driver.
He explained that drivers got around rules governing how many hours they were allowed to work by taking two tachograph cards, which record driver hours, speed and distance.
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To make it look like two drivers were operating a vehicle, when it was in fact one, drivers simply swapped the cards around at the end of a shift.
The driver's testimony is backed-up by a number of drug testing companies contacted by 5 live Investigates.
The companies did not want to be identified for fear of losing business but revealed they knew about a substantial number of positive readings among truck and van drivers.
One firm carrying out tests for a major haulage company for the first time found 10% of drivers tested positive for illegal drugs, but said none of them lost their jobs.
Told of 5 live's findings, another drug testing firm said in its experience 10% of drivers testing positive for illegal drugs in the transport industry was "not outrageous or surprising".
That was backed up by a third testing firm which revealed a company that employs around 5,000 courier drivers, found around 10% of its drivers tested positive for illegal drugs.
Another insider who assesses risk for major companies told the BBC how one firm tested 300 young van drivers in their 20s, and more than 40 of them tested positive for illegal drugs.
In evidence submitted to the Commons Transport Select Committee the Road Haulage Association (RHA) said the vast majority of its members do not test drivers for drugs as they do no believe drug use among drivers to be a significant problem.
Of those companies which do carry out drug tests the RHA said they reported no significant problem. However, the RHA admitted that a substantial minority of its members who do not currently test drivers suspect there is a significant problem within the industry.
The anonymous driver speaking to 5 live said: "It's nothing unusual to see drivers rolling joints while they're driving along the motorway and they're holding the steering wheel in their knees.
"That's why they're driving at 50 miles per hour. That's not a strong drug but it still shouldn't be taken while driving.
"But for the longer journey - eight or nine hours - they're taking ecstasy.
"I was talking to a lad two weeks ago and, literally 10 minutes before, had taken ecstasy to try and keep awake and get back up because he had another seven hours in front of him.
"He said he hadn't been to sleep for two days."
Campaigners are now calling for a change to the law to bring the road transport industry in line with the railway industry where there is a statutory duty to ensure drivers are drug-free.
They also want haulage companies to take more responsibility for their drivers' actions.
Julie Willis's 23-year-old daughter Louise Cooper was killed by lorry driver Lee Baker in 2008 - he admitted smoking cannabis the previous afternoon and was driving at 60mph in fog when he crashed into Miss Cooper at the roadside.
Traces of cannabis were found in Mr Baker's lorry.
Mrs Willis says employers should have a statutory duty to check the competency of their drivers.
The toxicology report on Mr Baker, seen by 5 Live Investigates, shows cannabis was found in a blood sample.
However, because of a delay in blood sampling the toxicologist was unable to say whether or not he was under the influence at the time of the incident.
He was jailed for 14 months after admitting one count of death by dangerous driving because it was not known whether or not the cannabis played any part in the accident.
Mrs Willis said she is angry that the Crown Prosecution Service (CPS) did not feel it was in the public interest to pursue the drugs matter.
In a statement, Chief Crown Prosecutor for the East of England Ken Caley said: "The most senior lawyers in CPS East of England, including myself, were involved in the decision.
"We thoroughly considered the material arising from the police investigation and concluded that there was insufficient evidence to prove that Mr Baker was under the influence of drugs when the incident which lead to the tragic death of Louise Cooper took place.
"We continue to offer our sincere condolences to Mrs Willis and her family for their tragic loss".
Mrs Willis told the BBC: "The crux of the matter is that drug testing must take place within six hours of the accident and the driver's impairment must be proven, unlike in the case of alcohol."
"The Vehicle and Operator Services Agency (Vosa) ensure vehicles have to be kept in tip-top condition but if the driver is under the influence of drink and/or drugs, the condition of the vehicle is irrelevant."
Road Safety Minister Mike Penning insisted Britain's roads were among the safest in the world.
"Drug driving is a menace, which is why we are going to introduce a new drug driving offence and approve screening equipment to make it easier for the police to test for the presence of drugs in drivers and tackle this irresponsible minority," he told BBC 5 live.
"We are currently putting together a panel of experts to advise us on the technical aspects of introducing a new offence of driving with an illegal drug in your body and expect them to meet in the next few weeks to finalise their terms of reference.
"We are not complacent and I am determined to crack down on those who continue to put lives at risk by drug driving."
You can listen to the full report on5 live Investigateson Sunday, 1 April at 21:00 BST onBBC Radio 5 live.
Listen again via the5 live websiteor by downloading the 5 live Investigatespodcast.
A culture of Class A drug taking is common among some drivers working in the UK road haulage business, say industry insiders.