Best thing to do is stay on the M20 until you come to the junction of the N18, M7 and M20, not sure of the junction number
Its Junction 1 of the M20 but I dont know what Junction number of the M7 it is. It could be 26 or something. I use it nearly every day.
The Tunnel is great but a lot of people in Limerick are being very miserly about it and are avoiding it. The queue on the Shannon side to get back onto the old D/C is amazing at rush hour.
It's not just being miserly, there is no access to the N18 from the North Side of the city except near the Radissson hotel, this in itself along with the roadworks near the Two Mile Inn makes the traffic look a lot heaveir than it should be.