Heavy duty trucks are causing many of the road safety and infrastructure problems in Mpumalanga and North West, Deputy Transport Minister Jeremy Cronin said on Tuesday.

The Presidential Infrastructure Co-ordinating Commission had identified the two provinces as having "serious challenges" around road safety and infrastructure, he told the Parliamentary committee on transport.

"Much of it has to do with the movement of heavy trucks," he said during a briefing by the Road Traffic Management Corporation

"Both are mining provinces through which heavy duty vehicles are moving, causing huge damage to road infrastructure."

He said much of the freight transport should be on railways and not on roads.

The department was working with public enterprises and Transnet in looking at branch railway lines.

However, there had not been a great appetite from the private sector to operate from these lines.

In general, road freight was not as effectively regulated as it should be and was an area government had to "push into".

The department had to move towards periodic vehicle testing to checks for roadworthiness.

"Stopping a vehicle on the road creates a visible presence which is part of getting a different mindset of road users," said Cronin.

The department was considering "periodic vehicle testing" as was applied to public transport vehicles, which were tested every six months.

"We have to start to make sure that apart from stopping vehicles on the road, there is a proper testing of vehicles," he said.

"And the priority should be given to heavy vehicles -- the freight vehicles."

Many freight hauliers were responsible but there were a lot of "fly by night operators".

Cronin said government was trying to expand the mandate of the SA National Roads Agency Limited (Sanral).

The department was looking at increasing co-operation between provinces and Sanral.

"We want to assist provinces in project management, tendering, and proper prioritisation," he said.

"It is something we want to roll out generally."