Indeed, other than the occasional special by the RPSI at Whitehead, the Enterprise and the rare engineering trains are the only examples of loco haulage in the north. Everything else is now in the capable hands of NIR’s CAF C3K (3000 class) and 4CK (4000 class) DMUs (or railcar’s as they are known in Ireland).
The 3000s are preferred for to longer-distance work - such as Belfast-Derry/Portrush as they have two toilets and more table seating, but 4000s were certainly diagrammed two out-and-back Derry line workings a few years ago, so I suspect it's relatively academic.
Indeed. It's unrecognizable from even 15 or so years ago, same goes for the IÉ fleet.
Some of the 4000s are now six car sets. Seven units are in the process of being extended.
Yes NIR railcars do operate to Dublin from time to time (Rugby extras and Enterprise replacement services etc). Cross border trains need to have compatibility with both systems signaling systems. I don’t think all railcars have that, but some certainly do as I have travelled on them.
Only C3K units 3001-3006, these have CAWS and IÉ communications equipment to permit use into the Republic. No C4Ks are so-fitted.
I had a read of a piece on the trains in a magazine and it says the C4Ks were intended as:
Certainly during the last two years, there have been periods where all Enterprise services were railcar operated. As I discovered to my cost!
IÉ have four 5-car 22000 Class ICR "Premier" sets and seven 3-car sets which are equipped with AWS/TPWS and NIR train radio for working into the North. Since "Premier" class was withdrawn from all InterCity routes except Dublin-Cork and the one through Dublin-Tralee service, there are plenty of surplus "Premier Class" 22000s - I imagine IÉ would probably use those exclusively to Belfast instead of the 201/D-D sets if given the opportunity.
