A simple bus route typology
To help think about bus network planning, I’ve sorted buses into two broad types; the buses we choose to catch and the buses we have to catch.
The former run frequently, along direct routes, have clear signage and, ideally, priority infrastructure such as bus lanes. The latter run infrequently, zig-zag back and forth and the bus stop is often no more than a sign nailed to a telegraph pole.
The first type is the domain of, well, everyone. They’re just a step down from metros, heavy rail and trams on the transport hierarchy. Onboard you’ll find people that are leaving the car at home and people that choose not to own a car because with a bus service this reliable, why would you bother? In Sydney, these bus routes are typically found running radially out from the CBD, although there are a few suburban outliers.
The second type of bus service can usually be found hanging out at your local railway station. Don’t expect to have any difficulty getting a seat. Typical passengers include those excluded from automobility for one reason or another.
Now don’t get me wrong, both types of services play a crucial role in providing accessibility. The problem is that what makes a good bus we choose to catch and what makes a good bus we have to catch, are completely different things. In the first instance the most important considerations are things like speed, reliability, frequency, capacity and hours of operation. For the latter we value all kinds of accessibility; low floor buses for wheelchair/pram access, frequent stops to maximise coverage, a one-seat ride to all local destinations and door to door service, especially immediately outside hospitals and shopping centres.
Jarrett Walker, world famous transport blogger, describes this as a problem of ridership vs coverage. He starts with a thought experiment. If a transport agency was a business it would want its services to attract as many patrons as possible. It would focus its resources on the corridors with high demand. Transport agencies do (usually) want that, but they also need to meet minimum standards of service. This draws rolling stock, staff and other resources away from the services that are designed to attract patronage, making them less desirable and thus less successful in their goal.
How this plays out in Sampletown
Here you can see a simple schematic of Sampletown. Each circle represents a neighbourhood with a mixture of housing, employment and other destinations. A large circle has three times as many residents, jobs and other destinations as a small circle. The travel time between two adjacent neighbourhoods is 5 minutes by bus. Sampletown Transit Authority (STA) has 2 buses. Let’s have a look a few different ways they could organise their service.
With good stop infrastructure and operating hours the green option could be a bus we’d choose to catch. It takes 30 minutes to run the route in both directions, so with two buses the STA could run a bus every 15 minutes. This option serves a third of the neighbourhoods, providing a high frequency, direct service to 55% of the population of Sampletown.
The red option is a bus we have to catch. This is what Jarrett Walker refers to as a coverage service. In Christchurch they’ve been referred to as ‘dropped noodle bus routes’, in Melbourne they’ve been described as ‘spaghetti-like’ and in Sydney most people would know what you mean if you mention the 3701 . The red route serves every neighbourhood; 100% of the population. It takes 1 hour 50 minutes to run the route in both directions and so with 2 buses this service could run every 55 minutes.
Trips on the red line take 3 times as long as they would’ve on the green line and thus are probably not competitive with driving, cycling or possibly even walking. On the other hand, in this option every resident of Sampletown can enjoy a one seat ride to anywhere else in town.
The $64k question
So, which is best?
Well it depends on the goals of the STA and the needs of residents. In small towns, the suburban fringe, areas with very high car dependence and small public transport budgets, coverage is usually the goal and so we see a lot of bus route maps that look an awful lot like the red line2. In big cities, areas with congested roads and lower car ownership we might see systems that look more like the green line. In Sydney, good examples include metrobuses (check out how stoked everyone is in this promo video), the 333 (Bondi Beach to Circular Quay) or the B-line B1 service that runs a limited stops, high frequency service from Wynyard to the Northern Beaches.
Public transport agencies are often between a rock and a hard place in deciding which to focus on. Too few coverage routes and the service is inaccessible; people are stranded. Too few direct, frequent routes and the service is unusable, those who can opt for other modes will do so.
There is a third way. Provided a transport agency has enough resources to provide both kids of service, they can do so. In this instance it is important to highlight which routes meet which goals. Good stop infrastructure, such as we see on the B-line, is a great way to do this. So is Newcastle’s 2018 bus network map. Without labeling services by what goal they seek to achieve we can end up with two bus routes with similar route numbers and branding that serve completely different purposes. They might appear the same on the network map and bus stop display but in actual fact one is a high frequency all day service and the other runs twice a day. This is not user-friendly.
Unfortunately for Sampletown with only 2 buses they can’t effectively employ this strategy. In order for a route to be the sort of bus we choose to catch it really needs to operate at least every 15 minutes. Ideally they could expand their public transport budget and run 3 or 4 buses, providing both coverage and ridership services. But perhaps that’s not politically tenable.
What they definitely shouldn’t do is attempt to have a single service meet both coverage and ridership goals because, chances are, it will end up doing neither.
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