Motorists are "highly likely" to face a second hike in toll rates within six months, according to Transport Infrastructure Ireland (TII).
Drivers are already to be hit with increases of up to 10% to drive on some of the country's main roads from this Saturday.
However, at the Oireachtas transport committee, TII chief Peter Walsh said it is "highly likely" that the rates will go up again in January.
He said although the toll rates payable in 2024 will not be known until mid-September, any increase in the 12-month consumer price index to August of more than 3% will guarantee the January toll hikes will go ahead. He added:
Mr Walsh said the increases will apply to all toll roads and the only vehicles that will not see an increase will be motorbikes.
This Saturday, the rates go up on nine on the 10 roads following a six-month deferral by the Government.
- Tolls on the M50 are set to increase by 30c for cars without tags to €3.50, while cars with tags face a 20c increase to €2.30.
- On the M1, M7, M8, N6, N25 at Waterford and N18 Limerick Tunnel, tolls for cars will increase from €2 to €2.10, while on the M3, car tolls will rise 10c to €1.60.
- On the M4, there will be an increase of 20c for cars to €3.20.
- The Dublin Port Tunnel is the only tolled road where there will be no increase.
Tolls had been due to rise at the start of the year in line with inflation, but this was delayed.
Although unable to provide final figures on the cost of the six-month deferral, Mr Walsh told the committee the anticipated cost of the deferral of toll increases on the eight toll concession roads, inclusive of advisory costs and additional administration charges, is expected to be approximately €7.6m.
In addition, the full cost to TII of tolls not collected on the M50 is expected to be in the region of €7.2m, he said, which is to be paid by the State.
Tipperary Independent TD Michael Lowry said the cost to motorists and the profits to the controlling companies is a source of “amazement” to the public. He said:
"The Exchequer has already taken the hit to compensate the controlling companies. I mean, how can that be fair or equitable?” Mr Lowry said before adding:
“How can it be so lucrative for these companies that everybody takes the extra charges? And those companies continue to make massive profits?”
Mr Walsh said three of the toll roads returned losses last year, while some of the profits were “marginal”, noting that the Waterford Bypass returned a profit of €912,000 in 2022.
Mr Walsh said the cost of operating and maintaining the national road network must be funded.
“If the funding provided by tolls is reduced, the shortfall must be made up by general taxation levied from people, some of whom are not using the toll roads,” he said.