The Circle Line sounds like a great idea.  Go either direction according to your needs,  with a total journey time of 90 minutes or so, you’re no more than 45 minutes from anywhere on it.

However, picking up on my comment on Jay’s article, there are certain logistical barriers that mean it is a non-starter in its proposed form.

The key assumption I will make in this piece is that the line from Antrim-Monkstown is doubled, including the total reconstruction of Mossley West station as the platform is currently on the site of the Down line (towards Antrim) and consequently the cutting will have to be widened, losing parking spaces (hey, this is what happens when you do things on the cheap!)  The reason for this assumption is that as a bare minimum, a half hourly service to Derry would absolutely require the line from Antrim to Templepatrick to be reinstated to double track, as the line to Monkstown had been until 1989.

Track constraints

Single track Lisburn-Antrim

A 15 minute frequency requires passing loops at 7.5 minute intervals – so it would need considerable land purchases to provide the loops, probably bridge replacements, and come in probably well over twice as much as the £50million estimated for a like for like reinstatement – even more again to run a spur into the Terminal.

The idea expressed to me privately that the circle could initially operate in one direction only sounds grand until you realise that this means a good service from Ballinderry to Belfast in the mornings (30 minutes all stops, 20 minutes if express Lisburn-Belfast), it means an awful service Belfast-Ballinderry via Antrim (50 minutes plus) in the evening, and a completely useless service Ballinderry-Glenavy (80 minutes) in the morning.

Capacity Monkstown-Antrim

Assuming double track is provided as above, this would require six trains an hour in each direction: four Circle Line and two through trains to Ballymena and beyond.  That impacts particularly on Kilmakee level crossing at Templepatrick, but the real issue is that  Circle Line trains must be capable of running at the same speed as other trains, or at that frequency, the through trains will have to run as slowly as the train in front (like the Enterprise and the DART).  Otherwise, it’s difficult to envisage how through services could operate without catching up on the Circle Line trains.  For that reason, any additional services should be run as heavy rail rather than light rail, with the higher operating speeds coming into their own on the long stretches between stations Mossley West-Antrim and Antrim-Lisburn.

New stations

Cathedral Quarter Station

This long-planned station would have been at Gamble Street, on the site of the privately owned car park we all know well from Line of Duty. The site is severely constrained, allowing for the need for lifts to access the platforms, and it stands at the corner of an industrial wasteland in an area known for drug taking which leaves it severed from the area it intended to serve – see also the decision to spend £10million replacing Yorkgate station with something with proper accessibility – the complaint there is that it is severed from Ulster University by York Street Interchange, but the truth is that Gamble Street is no less severed and probably less attractive.

Loughside Park and Abbeycentre stations

Loughside Park is the most obvious site for a new station, as the site of the former Tram depot still exists but I believe is no longer in public ownership.  Abbeycentre is more difficult, the former Greencastle station being buried under the M2 junction, because the Shore Road is 125m from the railway line at the junction with Longwood Road.  There is a brownfield site beside the Maxol garage, but the platforms and car parking for a new station would inevitably encroach on the park opposite Merville Garden Village, as would also happen at Loughside Park.  Despite mainly using a brownfield site in each case, the impact on the parks would be decidedly unpopular, and the watercourse between both sites and the railway line would also have to be considered.

The alternative to Abbeycentre would be the closed station at Whitehouse Park, but it has a very low bridge and there’s no space for Park & Ride – an absolutely essential element in any new railway station development intended to persuade drivers to take advantage – and the site is very constrained for parking in this residential area with its access to Gideons Green.

The key problem would be the impact on Larne line trains, which would be slowed down by a total of five or six minutes, especially going uphill towards Bleach Green.  This then impacts on how trains are threaded through the single track sections from Yorkgate to Lanyon Place and how they connect with trains to Bangor and Portadown.

Airport travel time

Connectivity to the airport only goes so far.  It has to be convenient, and the Circle Line is not convenient.

I estimated in September of last year that it would take at least 35 minutes for a train stopping only at Lisburn, Ballinderry, Glenavy and Crumlin to reach a new station at British Road, plus another ten minutes to transfer onto a shuttle bus to and from the Airport.

If that train stopped at all stations Great Victoria Street-Lisburn, as is proposed with the Circle Line, the time from terminal to Belfast City Centre would be at least 55 minutes.

That compares well with the Piccadilly line to Heathrow, but the tube (£3.30) is a fraction of the price of Heathrow Connect (£11.20) let alone Heathrow Express (£22).  It compares very badly with Tyne & Wear Metro (26 minutes from Newcastle Central).

Connections

The circle line would have no direct connections to services to Ballymena and beyond.  With a fifteen minute frequency being unachievable for the reasons stated above, you would be faced with the circle line train coming in at (say) 10.30 and having to wait 15 minutes for the through train in either direction to arrive.  A simple Antrim-Lisburn-Belfast service would offer better connections in and out of through trains at Antrim and Lisburn (including stopping trains Portadown-Belfast), and better connectivity for residents of Ballinderry, Glenavy and Crumlin at the price of having to change to an immediately available branch train at Antrim if you wanted to travel from Mossley West to Crumlin.

Conclusions

As exciting as a Circle Line sounds, it isn’t going to work.  A slow train that leaves you standing in the rain waiting for a bus to an airport doesn’t work, and nor does leaving people hanging around Antrim or Lisburn because the next train where they’re going is 15 minutes away (see also bus connections at Bangor train and buscentre, which have never been much more than symbolic, despite all the declarations of intent since 1997!)

What I remain convinced will work is to operate Antrim-Crumlin-Glenavy-Ballinderry-Lisburn-Belfast as a straightforward half hourly service which can be relied on to connect in and out of other trains at Lisburn and Antrim, possibly with the additional halt at Aldergrove – and it’s essential not to lose sight of the expansion of the villages and the potential for passengers to both return to and come anew to the train.  Don’t let the undeliverable perfect stand in the way of the good easily achievable.