It’s the divergent traffic flows, stupid

The Infrastructure Minister was on BBC Good Morning Ulster last week and, as ever, said some things which were accurate and others which were more dubious.

The Minister attained his mandate on a party pledge to prioritise infrastructure upgrades in the West (notably the A5 Derry-Strabane and Omagh-Ballygawley; and the A6 Derry-Dungiven and Castledawson-Randalstown). He has a case when he suggests that the media focus on the East (and the M2/M3/A12 York Street Interchange) because most of them live there and it is easier to do stories there.

However, his case is not bullet proof. In fact, most people in general live in the East, and Belfast commuters are seeing markedly high increases in commuting times. Nearly 120,000 vehicles pass through the York Street Interchange every day, whereas on most of the two stretches of A5 he is prioritising ahead of it barely 20,000 do. The East gets the bulk of infrastructure upgrade funding for the simple reason that it provides markedly better (and clearer) value for money.

But then, that case is not bullet proof either, because one of the reasons people live in the East is, directly or indirectly, that the infrastructure is better. Perhaps, if the A5 were upgraded, considerably more than 20,000 vehicles a day would use it, encouraging trade and leisure opportunities along its length?

Although then, are we not supposed to be discouraging vehicular traffic for environmental reasons?

As a matter of fact, detailed studies go into the social and economic benefit of each upgrade. In order, the greatest benefit is in fact offered by the A6 Castledawson-Randalstown upgrade, just ahead of the York Street Interchange, followed by the A5 upgrade taken as whole (although the potential complication there is that literally most of the benefit applies to the Republic) and then, some way behind, the A6 Derry-Dungiven.

Such studies are not perfect of course; there is a strong case that they overstate the economic case and existing traffic levels and do not place sufficient value on alternatives.

In the case of the York Street Interchange (I say reluctantly as it would have most benefit to me personally), it is clear alternatives should be considered whether it proceeds or not. There are several issues here, emphasised not least by last Tuesday’s chaos:

  • if more people used public transport, particularly into and out of the City Centre, fewer vehicles would use the Interchange anyway;
  • if journey times were more staggered, fewer vehicles would assemble at the lights around York Street at the same time (even if the total daily traffic flow remained the same); and
  • if the entry points were tolled, people would have incentives to investigate alternative means of transport or times of travel.

Ultimately this means speedy advancement of the Belfast Rapid Transit system and the purchase of new stock – the good news is both of these should be complete by end decade. It may also be helpful to restrict smart passes (free travel for over-60s) to non-peak hours, to stagger usage times, although the benefit here may be marginal.

However, it also means consideration of something else, a logical progression of what the Minister said but would probably never specify: there are too many free parking spaces for government employees in the City Centre. This has come to be seen as a standard perk, but in fact it should be brought to an end. It is this which adds literally hundreds, perhaps thousands, of vehicles to the traffic flow at York Street Interchange – and, what is more, it adds them all at the same time during rush hour! It is exactly this which earns Belfast the title of “most congested city in the UK” – it is not, in fact, congested as such but it does have one of the biggest discrepancies between volume of traffic at peak hours and volume of traffic otherwise. The principle is simple – if you want to park in the City Centre, you should pay for the privilege regardless of who you are.

There is also a growing move globally towards tolling motorways, a key part of the strategy which gave the Republic of Ireland the finest motorway/expressway network in Europe. Northern Ireland would have the added advantage of being able to implement this entirely electronically.

Yet, while all of this would help, none of it is quite the issue. Three locations have not yet been mentioned: the A2 Dee Street lights (exiting Belfast to the east); the M1/A1 Sprucefield Junction (exiting Belfast to the southwest); and the M2/A8 Sandyknowes Junction (exiting Belfast to the north). Unless these are sorted, the full benefit of an upgraded York Street Interchange will not be apparent.

The reason is divergent traffic flows. The ideal is to have traffic exiting the city moving on a freeflow basis at least until there is a major divergence. The most important example of this is the A2 east from Belfast, where the major divergence is at Knocknagoney but there are two sets of lights stopping mainline traffic in advance. The absolute necessity is to remove these lights (at Dee Street and the City Airport, where an alternative westbound access would be necessary); the absolute ideal would be to make Knocknagoney freeflow too, similarly to Tillysburn just east of it.

Likewise, heading southwest, the proposed M1/A1 flyover (thus removal of all roundabouts on the Belfast-Dublin mainline) is high priority, supporting divergent traffic flow in a way which would see traffic even as far back as the Westlink through Belfast travelling more freely in rush hour. Heading north, fixing Sandyknowes is admittedly an altogether more complex task, requiring a second junction further north (actually at about where the new Ballycraigy services are) to take Mallusk-bound traffic instead – but again, fixing this would have benefits all the way back to the M2/M5 Shore Motorway.

Fixing junctions in such a way does no the require hectares of new land to be covered in concrete and it would have very significant beneficial effects to Greater Belfast traffic. Tying it to encouragement of the use of public transport – by both carrot and stick – and marked benefits would be apparent for all. Toll some of it, of course, and money would become available for upgrades in the West.

That is why it is all about divergent traffic flows!


4 thoughts on “It’s the divergent traffic flows, stupid

  1. William Allen says:

    ‘gave the Republic of Ireland the finest motorway/expressway network in Europe’

    While I agree that the motorway network in the RoI has improved travel, I think it is laughable to consider it the best network in Europe. For a start the build quality is far below U.K. motorways and despite being very quiet in comparison I have noticed the M1 already starting to develop pot holes just like the rest of the roads in the RoI. Secondly the network in France is far better than those in either the U.K. or Ireland.

  2. In agreement in general. Esp on public sector car parking!
    I am bemused as why SF haven’t been called out on their sectarian pork barrelling. If they were pro United Ireland they would prioritise M1/A1 mess (not to mention Dublin Belfast railway) in reality they just want to shore up a declining vote West of the Bann!

    YSI should be priority or ideally Templepatrick/BIA/RUAS/Maze?Hillsborough dual carriageway

  3. andyboal says:

    Technically, Tillysburn is west of Knocknagoney – what was a simple crossing of the dual carriageway into Knocknagoney Road was incorporated with the Tillysburn roundabout to form the Tillysburn junction. You’re probably thinking of the Harbour Estate junction for Holywood Exchange.

    The Holywood Exchange junction does illustrate the problem – look at the space taken up by the loop on the south side. It’ll be difficult to make Tillysburn grade separated, with the ASSI constraining developments on the north side – on the other hand, there exists potential (if handled correctly) to link the road from the Ikea car park with a rebuilt road through the Airport grounds for traffic from Bangor. They could even allow Ikea to operate a long stay car park there.

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