Traffic planners must be kidding. The speed limits on M50 between N3 Blanchardstown and N2 Ballymun are set to 60km/h. To be fair, this is too much during the rush hours, when the maximum you can drive is 40km/h, but during the weekend... I did it myself today - drive at 60Km, and I was almost pushed out to the hard-shoulder! Literally nobody drives there at 60Km/h.
If the authorities really want drivers to keep their speed at 60, they should do something more efficient, or change the limits to something more realistic.