Lorry drivers are to stage a protest on the A9 over plans to introduce average speed cameras without increasing the speed limit for HGVs.
A call has gone out for trucks from across the country to head to the Perth-to-Inverness section of the road on a date yet to be finalised.
It follows the announcement by Transport Minister Keith Brown last week that average speed cameras will be sited along the 136-mile stretch of the road from Dunblane to Inverness to cut down on deaths.
Conor McKenna, the Inverness-based HGV driver who is organising the protest, said he expected at least 80 lorries from Inverness to join the protest but did not know how many would come up from Perth.
They plan to drive at 40mph to highlight the impact of the new cameras without an increased speed limit.
Mr McKenna said: "We could work with average speed cameras if the speed limit is raised to 50mph. The average speed cameras are fine on the A77, but that is mostly dual carriageway where lorries can travel at 50mph. The A9 is 80% to 90% two-lane road."
Lorries over 7.5 tonnes can go at 50mph on dual carriageways and motorways but must currently stick to 40mph on stretches of two-lane road.
However, vans and lorries up to 7.5 tonnes, buses and coaches, motor homes over 3.05 tonnes and cars pulling caravans can all legally travel at 50mph. Hauliers and drivers want parity.
Before announcing average speed cameras were being introduced, ministers were under increased pressure to raise speed limits for HGVs to 50mph.
The UK Government has already consulted on the issue and is due to make an announcement in the autumn, but so far the Scottish Government has resisted calls to have a 50mph pilot scheme north of the border.
However, it is understood ministers and police have not closed their minds to a pilot, but they want new data.
Earlier this week Highlands and Islands Labour MSP David Stewart lodged a Parliamentary Question formally asking if the Government was now considering a pilot scheme to raise the HGV limit from 40 to 50mph.
Pat Glancey, Road Haulage Association manager for Scotland and Northern Ireland, also backed the pilot.
She said average speed cameras without raising the speed limit would only mean more lorries being on the road as they would just take longer to complete their journey.
She said: "There should also be more places to allow lorries to pull off to let the traffic behind them overtake. There are very few such places on the A9."
However Superintendent Iain Murray, Police Scotland's head of road policing, said existing data and modelling suggested raising speed limits for HGVs on the A9 would increase casualties.
He said: "Police Scotland have agreed, along with rest of the A9 Safety Group, that we will look to gather new data on the A9, monitor the speed and flow of traffic, while policing the road in a high-profile way to influence and moderate road-user behavior. Then we will reconsider the proposition."
A Transport Scotland spokesman said: "There is consensus from members of the A9 Safety Group, of which both the Road Haulage Association and the Freight Transport Association are members, that an average speed camera system will improve safety on the route.
"Consideration was also given to a pilot increase of the speed limit for HGVs. However accident records show HGVs are involved in a higher proportion of accidents on single carriageway sections of the A9 than they are on other similar routes and the speed data shows the vast majority of HGVs are travelling above the speed limit.
"Average Speed Cameras create a level playing field for hauliers and allow other motorists to overtake more safely and within the speed limit."