If that is the problem, either fit selective door opening (costs money and time), skip Castlerea (possibly unpopular) or only run three cars beyond Athlone (a different set might have to be rostered and again, possibly unpopular). Extra capacity is extra capacity - nobody will be losing anything, lots of people will gain. Alternatively make sure the train **from** Mayo is only 3-car and have it use the loop
Castlerea is the problem they said on twitter.
The 18.15 up is always a 3 car but because its a Friday the 14.45 down is a 6 and the stock is required back in Dublin. Skipping the stop is best if there is to many passengers to split in Athlone. Some people won't be happy but a far higher number who are traveling further will be. Its rostered as a 2 3 pieces.
I would like to know what way they worked it on the 15 March. This 25 minute stop wasn't scheduled so either it did stop for that long or they tried both at Castlerea but of course Health and Safety comes into it.
Hopefully they monitor loads over the first week or two and make a decision best all round. Delaying the 18.15 by 15 or 20 minutes if possible but that could have further knock on affects.