Can Anyone Tell Me Why a Heavy Rail Link to Dublin Airport Can Not be Built in the Short Term?

Politics and the money.

A two-track electrified railway can be built a little faster than a motorway, at a little less cost... It’s just that in this country it’s been a long time since we ever did one from scratch.

The total length of such a spur would be at least 6 km, and would cost around €50~100 million (back of the envelope) to build assuming flat on-surface build with no complications at all. It might be possible to save a little by not electrifying this line, and relying on the Battery-EMU DART trains to service it, but not much in the grand scheme of things.

First problem is where the railway would need to run. A spur due west from the Northern line (branching just north of Portmarnock station) cuts through Kinsealy, Abbeyville and other really expensive places to live. That said, all of Dublin’s other salubrious neighbourhoods are on the DART, so it might actually work in favour of the proposal.

Next problem is getting in to the airport itself. This would require crossing the M1 and old N1, then getting through the outer areas to the terminal buildings. Once in the airport, this could be overground, and an overground line would allow a station serving the Airport Business Park. However, at some point it would need to go down, as Terminal 2 was built with an empty box below it for a rail/metro station, and the ideal from a passenger’s point of view is for all services to leave/arrive at this station.

Third problem: gauge. Metro will go to the airport, but Metro is built on Standard Gauge (1435mm) track. A DART line would be Irish Gauge (1600mm). To use that airport station, a dual-gauge track would be needed to allow both DART and Metro trains to coexist. This kind of setup has never been built in Ireland, but Australian railways have done it in the past. It would be possible to minimise the amount of track required to be twin-gauge, though - just enough to allow Metro and DART to use the same set of platforms. (Metro and DART may differ in electrification: DART is 1500V DC and in future will probably move to 25 kV AC, Metro could be either 750V or 1500V DC depending on how compatible they want to make it with LUAS.. but this is problem that is dealt with by railways across the world).

Journey time would be about 35~40 minutes in a post-DART+ scenario. Without DART+ electrification, it couldn’t be done at all, as there just wouldn’t be space for the extra trains.

None of the problems there are blockers, so, it is possible.

The next question is whether it’s worth the money it would cost. The only intermediate points are Kinsealy, Baskin and the Airport Business Park. Of those, only the Business Park would generate any significant additional traffic on top of the modest demand from the Airport (and it will be modest even before being split between Metro and DART). On that basis, it’s a non-starter. But looking wider, having a DART service to the Airport allows interchange with all of Dublin’s Inter-city rail lines, making it possible to get to Dublin Airport by rail from any other city in the country, which could tip the balance.

But, in the “short term”, I don’t think it’s feasible. It takes us far too long to do any kind of infrastructure in this country. If we decided tomorrow that the link needed to be done, then it would be ten years before a shovel could be put in the ground, and in the two intervening government terms, there’s plenty of time for the project to be canned for political expediency.

Out of curiosity, what would be needed to add more capacity to the Northern line?

There doesn't seem to be that many trains running on it, particularly when compared to other countries where double the frequency of trains seems commonplace

So would revamped and modernised signalling be sufficient?

How do you make it 2 miles? Every single proposed alignment I've seen puts it at around 7km of double track. The closest the railway track gets to the airport is well over 5km.

Biggest issue with airport connectivity right now is capacity. I'm regularly having buses pass me by due to being full. Loss of the 90ish capacity 747 and 757 and replacement with the Dublin Express coaches hasn't helped.

I have no idea how they got to 1.1 billion for that link except by perhaps putting most of it in a tunnel. For comparison, Dublin Port Tunnel is 2 x 4.5 km, and cost €750 M in 2006 money. The average figure of €15 M/km for a two-track electrified railway is from the UIC’s European costs database - it was cited in an article that I can’t find right now, so may have been old, but still, it’s hard to see how it could come in at that price. As a short spur with no onward expansion potential, even a single track with a passing loop in the middle would work - it’s only 6-7 km. 1.1 billion sounds like the estimators used MetroLink as a baseline - a project whose cost seems to go up every time it’s mentioned.

(Speaking of tunnelled stations, I believe that as part of the Dublin Airport T2 works there was an empty station box put in place ready for the arrival of Metro... an odd example of forward planning, and also a depressing reminder of how long we’ve waited for a Metro: Dublin Airport Terminal 2 opened in 2009)

The rationale for this is that while the distance from the airport is short to Dublin city centre, Dublin Airport is a national airport, and I would suspect that only a minority of passengers start or finish their journeys in the city itself. An easy link between the national rail network and the major stations would be very useful for reducing car traffic in and out of Dublin Airport (given the cost of parking there long term, many passengers would prefer to go by rail if they could), and for those within the DART’s catchment, a service to the airport would be simpler than having to change modes.

But that would be the ideal scenario. In the real world, I think a fraction of that cost spent on creating a predictable, frequent and reliable bus rapid transport corridor that linked Heuston, Connolly and Dublin Airport would be a better use of the money - as you say, the distance isn’t far; the problem with the current bus is it having to negotiate Dublin traffic, and a segregated busway (one with no taxis!) would fix that issue at a fraction of 1.1 billion euro... I honestly don’t have to be on a train all the way, but I do want to be certain that I’d arrive in time for my flight.

"In the real world, I think a fraction of that cost spent on creating a predictable, frequent and reliable bus rapid transport corridor that linked Heuston, Connolly and Dublin Airport would be a better use of the money - as you say, the distance isn’t far; the problem with the current bus is it having to negotiate Dublin traffic, and a segregated busway (one with no taxis!) would fix that issue at a fraction of 1.1 billion euro.."

Putting in the infrastructure that would support a tram or even a metro would be a criminal waste of money. Most of the construction cost would be land purchase, and it would be hobbled by its relative lack of capacity.

It was terminal 1 the train station space was left in - it was requisitioned into the Area 14 check in space some years back.

Such a line would not be competitive with buses in terms of frequency, capacity or journey time so it would therefore not be useful, certainly not useful to justify expenditure. And would be made completely redundant by metrolink. It also would not be built quickly. The state has never built a new heavy railway, how could it be done quickly?

If project 4north hoes ahead then such a line may be useful but before then no meaningful capacity is available.

Far more passengers would be arriving via Heuston than any station on the Northern line. With Metrolink serving the city-based population, any mainline airport rail link that doesn’t connect to Heuston will be a waste of money.

Rather than extending the one Metro line further and further away from Dublin, why not build a second line? Networks become more efficient when they interconnect.

"Better to house people in properly planned dense towns, rather then spread across a vast expanse of low density houses across West Dublin."

I'm not sure where this is coming from? I've suggested densifying close to the city before building "new towns" 20km (or whatever) from the centre - where did you get that I was advocating covering the countryside in semi-detached housing? The traditional centre (between the canals) is nearly 16km2 and there's over 200km2 within the M50. Dublin already has an enormous footprint relative to its population, I see no social benefits from extending the footprint before exploiting the massive amounts of brownfield, greenfield and underutilised land close to the centre.

The problem with building new towns, disconnected from existing centres is that they are only "cheap" if you forget about all the amenities people need and expect to be able to enjoy daily life. A "15 minute" new town is only any good if there's stuff within 15 minutes. So either you duplicate all the amenities (from hospitals, schools, sports/music/etc. venues, restaurants, shops, parks, etc, etc.) in the new town, at great expense, or you offer poor lifestyle to the new inhabitants.

Investing in dense buildings close to the centre - even if the land costs more - means that the new inhabitants immediately have access to all the amenities of the city. And that any new amenities are of benefit to existing Dublin city dwellers. More can be spent on providing quality public amenities as the spending doesn't have to cover multiple separated "centres".

There's a lot of theory around this subject - historically called the "new towns movement" - and historic experience with this approach in the post war years has been a mix bag - often negative. It typically takes decades before new towns become genuinely liveable and some never do.

Your proving my point: in population and area, Amsterdam is a larger city than Dublin.. And yet, its longest metro lines are the same length as the cut down length of one of ours.

Metros are not long-distance transport. The clue is in the name "metropolitan railway".

Luas is a symptom of the same disease.. We have a bad habit of trying to make single projects fix all problems, and overextension of Luas is an example. The western extents of Red Line are so far from Dublin they should really have been served by a new DART service. The Green Line just about gets away with its length because it's mostly on dedicated track which gives it relatively high speed for a tram.

To fix our carbon emissions, we need to densify our cities. To do that in Dublin, we need a high-frequency transport network that lets people get from one part of the city to another, not a collection of non-intersecting lines reaching ever further away from Dublin.

Amsterdam the same size as Dublin? No. Metropolitan Amsterdam is 2.4 million people; Metropolitan Dublin is 1.2 million. The hinterland of Amsterdam (its commutable area) dwarfs Dublin's in population. A 19 km metro line through Amsterdam has an enormous catchment; 19km in Dublin does not. But the Dublin one was supposed to be longer.

My observation is that by stretching out of the city, Metrolink is being shoehorned into a role that metro systems are not well suited to: serving outlying population centres. Talk of extending that single metro line out beyond Swords will just make that wrong choice clearer, and doing so while nothing in the city south west of Stephen's Green has any kind of mass transportation is a colossal wasted opportunity.

I feel that this is being done because, for various reasons, it is prohibitively expensive and slow to build a heavy-rail line in Ireland. Actually, it might be fast and cheap to do it, but nobody knows because effectively no new heavy rail has been built in this country for a century, whereas there is recent experience in building metro-like services (the Green Line is a classic "pre-metro"). I think it's also significant that Metro can be built without involvement from Iarnród Éireann, while DART would require them to be in charge of its construction. Looking from the outside, you'd think TII and IE hate each other...

Why is a metro bad for outlying regions? A metro has high frequency, but the trade-off is lower journey speed and and lower capacity per individual service (like a car's mpg versus top speed figures, that 25 minute service length is not available at the same time as the "with one train per 90 seconds" statistic). Outlying areas of cities tend to follow a tidal pattern: lots of demand for journeys in the mornings, lots out in the evenings, and that requires higher capacity for a very short time period. That's what commuter rail is good at: a long train every five minutes, running at higher speed.

Regarding interconnection, here is exactly where MetroLink will interchange with the existing rail lines. I count two:

From that map it's also pretty clear that Dublin has two huge mass-transport deserts - one in the Northeast, one from Glasnevin around to Coolock, and one from Rialto around to Dundrum. Metro does a very good job of reducing that Northern desert and connecting the North of the city to the centre. I have zero problem with that. It's once it goes north of the M50 that the questions needed to be asked.

"What's your argument here - that places like Drogheda, Navan, Trim, Naas, Newbridge etc., need heavy rail rather than metro? The map below probably backs that up."

Yes, that's exactly the argument. I'd include Swords as a borderline member of that group too, as it's separated from the city by a very low density area (which can't densify due to the airport approaches).

Ironically, it's the presence of the airport along its route that makes Metrolink less effective as a metro here, because the airport enforces a low-population zone around it, and metro works best when the whole length of a line runs through well-populated areas.