Cosatu will take to the highways in cars on Thursday to protest against e-tolling in Gauteng, it said on Wednesday.

"We won't be marching and demonstrating with our feet this time; we will be demonstrating with our wheels," Congress of SA Trade Unions (Cosatu) Gauteng chairman Phutas Tseki told reporters in Johannesburg.

"We will be driving slowly."

Tseki said this was not a strike and that workers would be at their posts on Thursday.

Cosatu leaders, full-time shop stewards, and leaders of Cosatu affiliates were expected to participate.

"We will do this for almost seven hours," Tseki said.

There would be two campaigns – one in Ekurhuleni and the other in Johannesburg.

Motorists would meet at 6am on the corner of Black Reef and Masakane roads in Ekurhuleni and on Jorissen Street in Johannesburg. The protest was expected to start at 8 am.

The two protests would take place on some of Johannesburg's busiest highways – the N1, M2, M1, N3, N12, R24, and R21.

Tseki said 100 cars were expected on each route.

The Johannesburg protest would move from Jorissen Street to Harrison and Wolmarans streets onto the M1 north. It would then proceed to the Buccleuch interchange and turn onto the N1 south.

At the Diepkloof interchange, the convoy would move onto the M1 north towards the Crown interchange then onto the M2 east, exiting at the Rissik Street off-ramp.

It would then proceed through the CBD to Anderson Street, Sauer Street, across the Queen Elizabeth Bridge then via Biccard back to Jorissen Street.

The Ekurhuleni convoy would join the N3 at the Heidelburg Road on-ramp at 9 am, then drive north along the N3, N12, R24, and R21 to the Nelmapius off-ramp in Centurion, and then back south on the R21, N12 west towards Johannesburg and back onto the N3 south.

Cosatu Gauteng secretary Dumisani Dakile urged motorists who joined the protest to drive with their headlights and hazard lights on. Some cars would also have banners.

Cosatu said it had received permission to protest from both the Johannesburg metro and Ekurhuleni metro. It had also wanted to protest in Pretoria, but did not receive permission from the Tshwane metro.

"This is the first time we [are] marching on the freeways with cars," said Dakile.

"In February, we will push the campaign to the next level. This is the beginning. Next time, we will close the roads for 24-hours and if government doesn't listen we might close them for a week," he said.