Victoria Police caught 156 heavy vehicle drivers operating while on drugs last year, a steep increase on the 2013 figure of 86 drivers detected under the influence.

That figure is up again so far this year, by 20 per cent, police say.

Assistant Commissioner Robert Hill said the rise in ice use among truck drivers reflected a general increase in the number of Victorians caught driving under the influence of methamphetamine.

"We have seen an increase in the number of drivers detected driving heavy vehicles that have been affected by methamphetamine in 2015 as compared to 2014," Mr Hill said. "We have seen an increase in the number of drivers more broadly affected by ice while driving a motor car."

Mr Hill said the overwhelming majority of truck drivers were law-abiding, but it was time the transport industry tackled the "misconception" among a few rogues in the industry that ice and speed increased driver alertness.

"There is a misconception that by using ice, those drivers may be able to stay awake longer, they may be able to be more alert behind the wheel," he said.

"That is a myth. These people use these drugs at their own peril. These people will be alert for a certain amount of time but that alertness is artificial - the need for sleep will increase and hence the risks on the road will increase."

Police intelligence indicates drug trafficking occurs within the industry, with drivers seeking drugs communicating on radio using coded language and purchasing drugs at roadside truck stops. Drug use is occurring both among long-haul drivers and those moving freight around Melbourne.

Last year, one in 14 truck drivers tested positive to drugs during targeted roadside testing by police. This compared to one in 674 drivers who tested positive for alcohol from random roadside breath testing.

Mr Hill said the targeted nature of drug testing skewed the figures, but the results were still cause for concern.

The Victorian Transport Association rejected any suggestion the truck industry had a problem with drugs.

"The transport industry directly and indirectly employs thousands of workers on and off the road, and is therefore a microcosm of contemporary society and its problems, including substance abuse," association president Peter Anderson said.

"However, the assertion that drugs are somehow a greater problem for transport workers and truck drivers than they are for other parts of the community is wrong."

Mr Anderson said the industry had worked hard to raise its safety standards.

"Road transport is a highly regulated industry," he said.

"The VTA and its member organisations spend considerable time, money and effort on programs that educate and inform drivers and other transport workers about managing fatigue, as well as the inherent dangers and risks of substance abuse and driving."