Gardai are developing plans to fine motorists speeding in the Port Tunnel.
New figures by the National Roads Authority show over half of motorists using the tunnel are speeding but none are being hit with penalty points.
Cameras currently set up at the entry and exit points are not suitable for prosecutions.
The problem is worse travelling south where 7 in 10 motorists are going faster than the 80 kilometre limit.
It's not safe for officers to use speed guns as there's no where to pull in.
Now it's thought cameras mounted at the entry and exit points will be upgraded to determine the average speed of motorists using the tunnel.
Legislation for average speed evidence exists but until now has not been used in court.
