The number of cars using Dublin’s Port Tunnel is rising so quickly that transport chiefs recommended higher rush-hour tolls to discourage private motorists from using it.In internal discussions, Transport Infrastructure Ireland (TII) said the volume of tollable traffic using the tunnel to dodge heavy morning commuter traffic was rising by more than 8 per cent a year. A board paper said the growth in traffic was “unsustainable” and could undermine the purpose of the road to give HGVs easier access to Dublin Port.It said an “overarching safety requirement” of the road was that standing traffic was not permitted, meaning congestion could lead to tunnel closures.The paper said capacity was limited by the ability of roads in the East Wall area of Dublin’s north city to absorb traffic. It explained: “In the AM peak, traffic congestion in the East Wall area is a routine occurrence, which frequently impacts on the tunnel.”It warned that the level of traffic in the Dublin Port Tunnel rose by 4.6 per cent in the first eight months of 2025 when compared to the same period in 2024. That was most apparent in the morning peak when toll-paying traffic climbed by 8.4 per cent.“Were this trend to continue, it would inevitably increase the occurrence of congestion southbound through the tunnel in the morning peak, adversely impacting on heavy vehicle movements into Dublin Port,” the briefing paper said.“As such, from a tunnel operations perspective, it is important that TII continues to discourage the greater use of the tunnel by tollable traffic in the AM peak.”TII recommended that the morning toll for citybound traffic increase from €13 to €14, describing the rise as “modest”. It added that it would allow TII “to incrementally discourage” overuse of the tunnel by non-commercial vehicles.M50 tollsThe paper also recommended increases in tolls on the M50, saying it had been standard policy to set them at the maximum level.“The revenues collected are a vital funding source to the operation and maintenance of the national road network,” it explained.It said that without a commitment to make up any shortfall, M50 toll income not collected from drivers would mean an equivalent reduction in funds available for road protection and renewal.The TII board was also told that its role in setting tolls on eight other major roads around Ireland was “more limited”. Public-private partnership contracts set out the rules for confirming the level of toll that could be charged.Asked about the records, a spokesman for TII said: “The primary function of the Dublin Port Tunnel is to cater for HGVs.”HGVs travel free through the tunnel because the majority of goods into and out of the island come through Dublin Port Tunnel and require safe and efficient access to the national motorway network.“Trying to reduce general car traffic by charging a higher toll during peak travel times reduces the potential of incidents and delays to those HGVs,” he said.