18:40 from Heuston

[portarlington_user]

Apologies if this has already been brought up elsewhere, but can anyone tell me if there's a reason why it never boards on time? I usually arrive to Heuston at half 6 for this train and yet there is always a Q for the train. More often than not people are always allowed just walk on with no ticket check.
It generally does leave on time but I'm just interested to see why the boarding delay is.