Given that there are to be 45 4-car and 18 3-car sets, then there will be occasions when strengthening a 4-car train will be impossible if there are no 3-car sets to hand. I have not looked at the details of platform lengths in the Network Statement, but I have a hunch that very minor platform lengthening might enable 8-cars to operate on some routes.
Storing a few intermediate cars and reducing the number of 4-car sets to (say) 40 would increase the ability to form 7-car trains, and enhance operational flexibility.
Two other issues: Laois traincare depot is built with each shed road serving one 6-car or two 3-car sets: a four car set will leave unoccupied space and may complicate depot throughput. Also the tailoring of fixed infrastructure to existing traffic patterns can reduce operational flexibility. For example:
- WRC platforms of 90m, built on the assumption of 4 2600, 2700 or 2800 cars max.
- the upgrade of the Sligo line was done on the assumption of Dromod being a crossing point, so when the timetable was enhanced they had to spend more money on Boyle.
Maybe the reconfiguration is necessary, but it's more complicated than at first sight.