Saturday, June 03, 2006

Network type and city size

As towns and cities increase in size, the type and role of their public transport networks change.

Moving from rural to major urban areas, and from least sophisticated to most sophisticated, the progression is normally as follows:

1. School bus routes only.
2. Seniors door to door shopper or community bus operating a few days a week.
3. Fixed route/fixed timetable town buses operating a few services in the middle of the day, again mainly for shoppers going into town.
4. Fixed route/fixed timetable town buses offering the above plus am and pm peak hour service for shoppers and town centre commuters.
5. Fixed route/fixed timetable town buses offering the above plus weekend and evening services suitable for shoppers, commuters and leisure trips into town.
6. A web-like network of scheduled services with cross-suburban as well as CBD routes and easy transfers between services.
7. A web-like network of services, with trunk services to the CBD using heavy and/or light rail and local cross-suburban feeder routes using buses.
8. A web-like network, with both trunk services to the CBD and the more important cross-suburban circumfrential routes using light and/or heavy rail.

The types of centres served by these services are as follows:

1. Settlements up to several hundred have only school buses and, if they are lucky, the odd coach to a large regional city. 2. Larger towns up to a few thousand might also have a community bus for the seniors. If on a passenger railway, regional trains may stop there. 3. Towns around 10000 (eg Sale) tend to have a rudimentary fixed route bus system but with operating span and frequency only suitable for day shoppers (not work commuters). 4. Bigger centres of 30 000 or more may have services before 10am and after 4pm, allowing some use for town centre commuters. 5. Even larger cities (such as Geelong) have much the above, but with weekend and some evening services. However as with examples 3 & 4 all routes converge on the CBD. 6 and 7 are more characteristic of Australian capital cities such as Sydney, Melbourne and Perth. However due to limited services the network may still be CBD-centric, so may retreat to being closer to 5 during these times. 8. is only found in the big transit cities such as Paris and Moscow, and there are no examples in Australia.

The least sophisticated networks (1 & 2) cater for special-need groups only, so can't legitimately be called 'public transport'. Those who aren't in the nominated groups cannot use these services. They they will drive, cycle or walk, so the public transport modal share in these centres is small.

Networks 3 to 5 represent conventional small city public transport systems, and can cater for varying types of town-centre trips. Network coverge, operating span and service frequency tend to governing the range of trips it can cater for and represent the main differences between 3, 4 and 5. Inter-suburban trips may require backtracking to a town-centre terminus, so are less attractive.

Networks 6, 7 and 8 represent the most developed systems and are the most versatile. They can cater for a wide range of CBD and cross-suburban trips throughout the day and night. Cities with 7 and (especially) 8 offer car-competitive travel times and have the highest modal share for public transport.

1 comment:

Anonymous said...

Excellent Peter

Maybe we could adapt it for the Transport Textbook.

I have a strong feeling for this. I also find a dimension of town/city 'purpose' that affects what happens.

Hence why I would probably use a Christchurch style solution in Adelaide, though it is much bigger, and why I support the Stadtbahning of Adelaide.

Apart from a couple of very long corridors, I don't see much potential in heavy rail for Adelaide. The city is very dispersed, and suitable for buses with high capacity light rail on most spines. The CBD is a weak attractor.

Yet Perth, which frequently talks about Light Rail, is probably already past the Light rail stage for its longer distance routes, and is picking up sizeable heavy rail traffic. And the CBD is this case is a strong attractor.

Wellington, because of its legacy, is probably on the border and like Adelaide (though it is significantly smaller) so probably should have Light Rail to penetrate the city and only the couple of long distance heavy rail routes.

Newcastle is a complicated one. It services to Maitland and Lake Macquarie are really interurban, not suburban, and the suburbs as such are poorly served by rail transport.

The spines of the Newcastle urban area would probably make good light rail turf, but until they get their planning sorted and bus ridership up, I probably wouldn't bother.

I have read that the University is a bigger attractor than the CBD so getting that right is the key.