Over the last few weeks I have been putting together a series of posts about Paul Mees’s new book Transport for Suburbia: beyond the automobile age. It really is an excellent book, and I am getting to the real ‘meat’ of the book about how we can actually make our public transport systems drastically better. A key part of improving public transport systems in cities with relatively dispersed trip patterns (ie. Auckland) is what Mees calls “The Network Effect”. The network effect happens when you make it easy for people to transfer from one service to another, as it brings so many more locations within relatively easy public transport access.
To illustrate the network effect, Mees uses the hypothetical city of “Squaresville”, which is illustrated in the diagram below: The Squaresville scenario is basically the worst possible situation for traditional public transport, with trips having absolutely no pattern at all. Mees explains further:
The city has a grid road network, with ten north-south and ten east-west roads, at intervals of half a mile or 800m. travel patterns are completely random, with no dominant pattern of movement. Each of the city’s 100 square blocks produces 100 trips a day: one internal trip (made on foot), and one external trip to each of the 99 other blocks of the city – giving 9900 external trips in total.
Squaresville has ten bus routes that grew up in a free market environment, with each operated by a different firm. There is one route along each north-south road, reflecting a past era when this was the dominant pattern of movement (Figure 9.1A). This means that each resident of Squaresville has a bus within 400m walking distance, but can only reach the nine other city blocks lying along her or his bus route, giving access to 900 daily trips out of the total of 9900. Assume that public transport attracts a third of the trips it can theoretically serve, this gives a total of 300 trips (a third of 900), or a city-wide mode share of only 3 per cent.
This would be a fairly good approximation of the current bus system in Auckland I think. There are many “suburbs to CBD” routes running roughly parallel with each other, but very few crosstown services linking them up. Furthermore, the cross-town services that do exist generally run at very poor frequencies, take bizarre backstreet routes (yes I’m looking at you 008) and integrate extremely poorly with the suburb to CBD routes.
Now, imagine that the government of Squaresville wants to do something about the low rate of public transport use in the city. It pays the bus operators to double service frequencies on Squaresville’s ten bus routes (Figure 9.1B). With a typical demand elasticity of 0.5, this would increase patronage by half, to 450 trips per day or 4.5 per cent of the market. Occupancy rates will fall, since patronage has grown more slowly than service levels, and fare revenue will not cover the extra costs. Subsidies will rise, cost-recovery will worsen and so will greenhouse emissions per bus passenger. Public transport is still of marginal importance, but it has become less efficient in economic and environmental terms.
One could argue that this has been what has largely happened in Auckland over the past decade. We’ve spent more and more money on the existing services, and while that has certainly led to some level of patronage increase, we haven’t really made the kind of gains we would have expected. This is clearly shown in the table below, which shows that over the past decade subsidies for public transport have increased from $45m a year to $145m a year, while patronage has only grown from 44m trips a year to 58m trips a year – barely keeping up with population growth. Is there another way? Returning to Squaresville, Mess suggests so:
Imagine instead that the additional buses are used in a different way. Ten east-west routes are introduced to complement the ten existing lines and create a grid network, as shown in Figure 9.1C. The number of trips served directly doubles, to 1800 [as there are now 20 routes], but by transferring between routes, passengers can now access the entire city, so the network also serves the remaining 8100 trips. Squaresville’s planners do everything possible to make transfers convenient, providing integrated fares, convenient facilities and coordinated timetables. But since so many transport analysts say that passengers dislike transferring, let’s assume that the mode share for trips requiring a transfer is only half that for direct trips, that is one-sixth. So the total number of public transport trips is one-third of 1800 plus one-sixth of 8100, giving a total of 1950.
Under the second model of service provision, public transport’s mode share has jumped dramatically, from 3 to 20 per cent. Service has increased 100 per cent, but patronage has grown 550 per cent, giving an elasticity of 5.5. Increased revenue would more than cover the costs of the additional service and occupancies would rise substantially, reducing subsidies and greenhouse emissions per passenger.
Now while Squaresville obviously isn’t real, I think it shows that dispersed trip patterns certainly does not have to be the death-knell for successful public transport. There’s an interesting comparison in terms of how airlines operate – in that you don’t expect to be able to fly directly from New Zealand to a great number of random places in Africa – for example – because the demand would be too low for a direct service. Nobody would wait a week for a direct service when there are much higher frequencies that involve transfers at major hubs like London or Singapore. Mees uses the example of direct airline services between Australia and many European cities to make this point clearer:
There were once infrequent direct services between Australia and other European cities, but this was at a time when fares were so high that airlines could run half-empty planes and still make money. The transfer at London or Singapore is one of the costs of the dramatic fall in real airfares in the last three decades, but it has also allowed Australians easier access to a larger range of European cities.
The point is that to achieve efficiencies and allow services to be provided at regular intervals to an incredibly wide range of places, transfers are necessary. Just as they’re necessary in the airline business, they’re necessary in public transport. Of course there will be the “cost” of the annoyance of having to get off one bus and onto another (or onto a train), but if that ‘cost’ means the benefits of being able to simply walk up the road without checking a timetable, jump on a bus you know is coming every 5-10 minutes, get off somewhere and jump on another bus almost immediately and that process will get you just about anywhere, surely it’s worth it?