Loop routes: great connectivity or just loopy?

I was having a trawl through recent changes to the London Underground network and noticed one change that had somewhat slipped past my attention – the adjustment of the Circle Line to something that’s now more of a “spiral route”, with the addition of a section from Hammersmith to Paddington. One of the reasons for making such a change could obviously have been the desire to get more services to Paddington, but through reading up on the change it also seems that there was a desire to shift away from the “loop” route patterns of the Circle Line.

The diagram below shows what the “Circle” Line looks like today: The difficulties in operating an orbital/loop route are noted in the Circle Line’s Wikipedia page as a reason for the change:

Orbital routes have an intrinsic problem of timetabling robustness. The trains are constantly in service and so there is little scope for “recovery time” if they are delayed. A single delay can have long-lasting knock-on effects and be much more disruptive than on a non-orbital railway. Recovery time can be created by timetabling longer stops at some stations, but this increases journey times. The current spiral route supposedly removed this problem because of the recovery time at both ends of the route.

That got me thinking about loop routes in general, and particularly Auckland’s best known example of a “loop”, the Link Bus service. I don’t catch Link buses particularly often, but when I do it is fairly plainly obvious that the buses suffer from what’s outlined above, probably to a greater degree than happened on the Circle Line because buses, when operating in mixed traffic, have many more possible causes of delay.

Link buses have an unfortunate tendency to “bunch”, because slow boarding times and unreliable traffic conditions mean that the first bus gets slowed down, while the bus behind it slowly catches up because it doesn’t have to pick up passengers and can therefore travel quite quickly. The longer the route gets, the more bunching you end up with – the end result quite often being three Link buses travelling one after the other, and then a huge gap to the next one.

Now this kind of thing can happen on any bus route, but the difference with non “loop” routes is that you generally have the opportunity to schedule a bit of “buffer” at the start and end of each run, meaning that if a bus is late (or early) there can be a re-timing of the service through the buffer, to give the best chance of starting its next run on time and therefore minimising the potential for bunching and unreliability. With the Link route (or any loop route for that matter), you are likely to have passengers travelling along each part of the Loop, (after all that’s one of their great strengths) which means that every time you have a “delay point” you annoy the heck out of passengers who have to sit at a bus stop for a few minutes twiddling their thumbs for seemingly no reason. I’m sure many readers would have experienced the “Victoria Park wait” on the Link bus over the years – to their great frustration (particularly as the bus drivers never seem to tell you how long it’s going to be).

When you’re trying to make public transport a more attractive option compared to driving, by improving its speed, reliability, convenience and so forth, having bunching buses or hugely long waits for seemingly no reason at Victoria Park don’t really help. I know of a lot of people who’ll avoid the Link bus for these reasons.

Yet I have to balance this against the advantages of “loop” routes. They do offer a connection between such a great number of places – particularly when it comes to the Link bus. Ponsonby to Newmarket: sorted; Parnell to downtown: sorted; Grafton to Ponsonby: sorted. If there are ways to minimise the unreliability, bunching and annoying waits associated with loop routes, they certainly have their many advantages.

So what might be a way forward on the issue of loops? I’m certainly not advocating for getting rid of the Link bus anytime soon – as it has been a significant success, despite its flaws. The high frequency and good connectivity of the Link has clearly struck a chord with the Auckland public right from when it was first introduced in the late 1990s. But how might we reduce the problems associated with the Link? Can we put in better bus priority measures at key points along the Link’s route where it experiences delays? Will faster boarding associated with integrated ticketing help reduce the ‘bunching’ caused by slow boarding? Can bus drivers be made aware of how far behind them, or in front of them, the other Link buses are – and adjust their driving accordingly? Is there a better place for the Link bus to pause than Victoria Park – which seems a very bus part of the route’s operation? It would be interesting to know the answers to these questions.

Furthermore, I also think that we should be wary of introducing further ‘loop’ bus routes – particularly if those routes are going to be longer than the current Link. The longer the route, the more opportunities for delays in mixed traffic, the more opportunity for bunching due to slow boarding and the more difficult it becomes to keep the route ‘on-time’ without having to introduce extraordinarily long waits at various points along the route – guaranteed to annoy the hell out of bus catchers.

So I suppose in summary I think loop routes are best if they’re kept short and if we can get as good bus priority along the route as possible. This minimises the opportunity for unreliable services and the opportunity for bunching. Furthermore, in the case of the Link perhaps we should look at having a number of “waiting points” around the route, in places where patronage is at its lowest, to allow the buses to keep on time without making passengers wait forever – as currently happens on occasion around Victoria Park.

I am curious what others think though – are Loop routes great, or are they a loopy idea (please excuse the terrible pun)?

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