It's hoped new speed checks in the Dublin Port Tunnel will reduce collisions by half.

Gardaí are introducing new speed checks from midnight tonight, by way of average speed cameras.

The cameras which are located at the start and end of the tunnel will check how long it takes for a vehicle to pass through.

Eyes on the tunnel in the Dublin port tunnel control room

Average speed enforcement comes into effect in tunnel from midnight @TodayFMNews pic.twitter.com/Tt4GYJz5tS

— Nicole Gernon (@nicole_gernon) May 31, 2017

It's after a 40 per cent increase in traffic in the past 5 years and recent data collected which estimate that only about half of vehicle observe the 80kmph speed limit in the 4 and a half kilometre long tunnel.

Anyone found to be taking less less than three and a half minutes to complete the journey will receive a fine and penalty points.

Assistant Garda Commissioner Michael Finn has been explaining why they chose this average speed method: