A very sensible call in the Assembly yesterday to re-open the Antrim-Lisburn railway line was turned into something different by the media, namely a call for a rail link to the airport. That latter is much, much more complex and is a different case entirely (and the re-opening of the Antrim-Lisburn line, a good idea in itself, should absolutely not be predicated upon it).

The call for a railway link to the Airport is one of those things that people believe to be obvious but never take time to think about. The Twitter generation, sadly, is less inclined to think than it should be…

Let us start there: when are the biggest queues at the airport?

Very early in the morning.

The “red eye” flights to London and elsewhere are most packed (and most expensive) early in the morning – often between 6am and 7am – precisely because that’s when most people need to travel for a day’s (or even week’s) work.

To get to the airport for even an 0645 flight, you would want to be there at 0545, thus on a train leaving Central at 0515 at the very latest. Of course, you would want to get to Central by train – so there would need to be options from, say, Carrickfergus or Bangor from 0430. Remember, even this does not cover earlier flights! (There is no point running a service only from Central if people have to drive to it from the suburbs – they may as well just keep going and drive to the airport!)

Currently, the train system begins operation at 0600.

So there is an immediate problem. The whole system – drivers, station staff, security, porters etc as well as the actual trains – would need to come into operation a full hour and a half (actually really two hours) earlier. This would come at significant cost to the whole system (at least in Greater Belfast), all for one service! This is not seriously viable financially on current passenger numbers (given there is no guarantee huge numbers currently travelling to the airport by car or coach would transfer to the train anyway).

On top of this, services would have to be reliable and regular. This is a problem in itself because in fact there is no other reason to go to the airport other than for flights. Most airports which have rail connections (a small minority among comparable populations, contrary to popular opinion!) also have large conference centres, business premises, even entire industrial sites adjoined to them. It is hard to see the point in any service which is less than hourly (as it would simply be of no use to most people embarking on or meeting particular flights), yet any service which is as regular as that would still surely be fairly empty through most of the day (and thus would make a considerable loss).

It gets worse. An additional regular service like that would put impossible pressure on the Dargan Bridge, currently single track into Central from Yorkgate (unless, ludicrously, all services went via Lisburn, which would surely render them unlikely sources of transfers from the coach services available). The Bridge itself is due to be dualled as part of the York Street Interchange project, but the track would also need dualled, at considerable cost. The good news is that this is planned. The bad news is it is planned for the year 2040 (no joke). Again, all for one service (a service which comes at great cost to the overall system while itself being loss making).

The case for the Lisburn-Antrim service is clear cut (looking at transfers to bus routes etc.), but this is in its own right. The case for a link to an airport which has no other facilities and relatively few passengers (not least because it shares them with another nearby airport, but also because of the size of the area it realistically serves) is however much harder to justify. The public may want it, but try asking them to pay for it…