I very much enjoyed the Andy Foster column in the current Transit. There was much sense in his justification for even headways. A no brainer you’d think but not every operator gets it.
You’d expect the co-ordination mantra from a TAS consultant (even if this holy grail isn’t always quite achievable with scattered outer termini). Yet, to some, I fear Foster was talking quantum physics. This is the physics of particles. Atoms behave in an entirely different way to the gravity of Newtonian physics.
Newtonian or classical physics says that on the snooker table, the cueball will cannon the red into the opposite pocket. In unpredictable quantum physics, the red may go straight through the cushion to the floor (as might happen with gamma radiation).
Buses don’t always operate in accordance with the laws of classical physics. There are random elements such as congestion & roadworks, not to mention drivers, people & passengers. Foster sets out the case that unco-ordinated headway buses see their irregular gaps between exaggerating the inevitable bunching. The gaps will widen rather than reduce. Result: a smaller proportion of the resource carries a higher percentage of passengers.
Foster illustrates this with two services at his stop, one of every 6/7 minutes, the other every nine (sic—sounds like Preston). The longest theoretical gap is every seven minutes. This is an uneven service so buses in the longer gaps take a higher proportion of passengers. The gaps continually widen. When this extends to 10-12 minutes, Foster feels a surprisingly high proportion of passengers consider getting their cars out when it rains or for short distance trips; or they simply walk.
You can't avoid bunching but even headways can reduce the widening gap syndrome. There are plenty of examples where growth is significant simply by offering a co-ordinated headway where once it was not. As good an example as any comes from Transdev Yellow Buses, with first year ridership increasing by 20 per cent, another five per cent the following year and a further 15 per cent with national free travel.
And the reverse is true, says Foster, where a service is cut from every 7/8 minutes to every 10. Every 10 is still good. It's the holy grail. Yet, in his actual example, passengers declined by 12 per cent. Passengers therefore notice subtle changes and react in physical ways, quantum or otherwise.
Friday, 13 March 2009
Of Quantum Physics, Headways & Bournemouth
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3 comments:
Like the spelling mistake in the title.
The main problem with the co-ordination item is when developing networks you end up developing extremely convoluted and complicated timetables for the outer extremes of the network, that are so fragile that to reduce the service to one area from (say) 4 to 3 per hour demands a recast of all other services round and about.
In the Wakefield and Kirklees areas of West Yorkshire (where Arriva operate) nominal co-ordination on some corridors is fairly solid but unfortunately Arriva have got the 'headway' message but not the 'simplification' message so much and so usage is low and falling and satisfaction is low too. While North Kirklees particularly is a difficult area to simplify with a fairly polycentric set up and non-urban areas fairly rural in nature, Wakefield is similar to many overground cities.
Without a doubt a lower frequency service overlayed on a higher frequency corridor (normal for some radial routes) adds to the offer. Real time may help too. Low frequency - or even irregular timetables - isn't a barrier to high rail use, after all.
This is more a comment on RTI - and thanks to 'A. C. Umbrian' for the link to the older post. I must confess that I had not seen that post, as it was probably before I became a regular reader of the blog.
This does all remind me of a comment made by an interested observer when an RTI system was being developed in my home city, in the early 90s.
The cost of developing the said RTI system was reported as being approximately the equivalent of the capital cost of 80 new buses. The comment suggested that the RTI system would helpfully tell an intending passenger when the bus was running late, and if that delay were significant, then the intending passenger could walk or find another means of travel. Thus the 'intending passenger' becomes a 'lost passenger' (= lost revenue). Without RTI, the intending passenger would probably wait for the bus - which means no loss of revenue, although, no doubt, some loss of customer satisfaction. If the money had been spent on extra buses and a more frequent service provided, then the delay would probably not have been so great, and the loss of customer satisfaction equally not so great.
Of course, 80 extra buses would probably not have been needed to effect a worthwhile improvement in frequency; and, of course, I am also aware that there are many other costs to be considered - but reading the post from 2006 about RTI, and the TAS conclusions, I am inclined to think that my acquaintance of 15 years before was right. From the operator's perspective, the money could more usefully have been spent in other ways.
The other thing about RTI is that it might make people wait *longer*. If you're on a half hourly frequency and the bus doesn't appear to show up after 10 minutes, say, one starts to suspect a cancellation and is tempted to use another mode. If a RTI system tells you it'll be there 11 minutes late, you might well wait for it.
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