For this assignment I’m going to compare two similar networks: the city bus and the subway. I’ll be drawing on experiences of public transport in several cities around the world, including the famous subway trains of New York, London, Paris, and Moscow. Both bus and subway networks are modes of public transport - in most cities you can use the same tickets for bus or tube. And yet they differ significantly from each other in several crucial ways.
The first point of differentiation is one I like to call the “Wonderland” principle, and it states that subways run, in the main, below the surface of the earth; buses (barring the odd tunnel) run mainly on the surface. A corollory of this observation is that subways run in tunnels (on tracks, although for our purposes this is not that important) while buses run on roads or streets.
The streets of a city form a reasonably comprehensive network of routes. Pedestrian zones, narrow lanes, one-way systems, and in some places low bridges, will restrict how traffic can move. There are reasonably few locations in a city that cannot be reached by road, even if the route is made complicated by such restrictions. Tunnels, on the other hand, go where they go. A train in a network of tunnels can only go where there are tunnels. This means that the subway has a limited number of possible routes, whereas the bus can theoretically travel wherever there is a need for buses. Administration and bureaucracy may slow down the reassigning of bus routes or the creation of new ones, but those decisions won’t have to involve digging new tunnels under the city.
Another aspect of the underground/overground difference relates to sensory clues as to location. A person on a bus knows where they are because they can see where they are. A person being moved along a tunnel on a fast-moving tube has no way of orientating themselves. They know where they are because at each station there will be a large sign indicating the name of the stop. Bus stops don’t have names assigned by the bus company – their names are assigned by where they are, and that name may differ from user to user. My “get off near a shop called Bill’s News” may be another person’s “ring the bell when you turn a corner off Killarney Road”.
This need for directions is another important difference in these two networks that ostensibly do the same thing: taking a bus involves a consirable amount of local knowledge. You must know the route the bus will take and be able to identify your desitination when you arrive. On a subway system, once you can read the schema of coloured lines you just need to figure out the name of where you are and the name of where you’re going (both assigned by the subway company) to be sure of arriving at the right place.
It is of course possible to make a bus map, and indeed in most cities with a bus network such maps exist. A bus map is not quite the same beast as a subway map however. A conceptual diagram that allows a user to navigate a subway system need bear no relationship at all to geography – all it needs to show is the network of lines (including station names) and where they connect. Armed with such a diagram a new user of the system can easily identify their intended route from start to finish without having to trouble themselves with anything as complicated as a street map or any sense of direction. A bus map needs to be reasonably to scale, or else it becomes impossible to determine how to get from one bus to another. Bus maps that contain sufficient detail to transfer easily from one route to another are rare – even a scale map won’t draw attention to the kinds of landmarks needed for a user to know when to get off and how to find another bus stop. Unless of course they are already familiar with the terrain and the network.
A subway network is a tangible thing. Once a passsenger descends into the earth to take the train, they dispense with their normal tools for finding their way around and make use of signs, names, and conceptual drawings provided by the train company in order to get to where they are going. The bus network is a notional network – there is no permanent structure that marks it out as there is with the subway. The buses themselves moving on their routes make up the network, but unless you watched from the air it wouldn’t be possible to see it. It is a network that you come to know, not from a diagram, but from experience. Taking the bus is a skill that is built up with regular use. Long-time users gradually get to know more of the network. Tourists will have little trouble with the subway, but will struggle to get around on the bus. This is why they have their own buses especially for them where there is always someone telling them exactly where they are.
Two forms of public transport, two different networks. The bus system demands user expertise to be used efficiently. The subway demands nothing of its users – it comes complete with map, signage, audio cues, and naming of stations. The bus system is flexible – it can change to meet the needs of users, as it is limited only by the road system on which it runs. The subway system is more fixed – population growth in an area won’t grow a new tunnel there. The trains can only get to places that are already served by the network of underground tunnels (without significant engineering works). The two networks compliment each other in providing comprehensive public transport to a city – the flexibility of the buses offsets the more fixed nature of subway routes. The subway’s ease of use means new users can easily get themselves around the parts of the city they are likely to need to go. The bus system means that people with more local knowledge and more regular need of transport, in other words expert users, can learn how to get to pretty much any part of the city using a combination of the two networks.
Dee Harvey
September 22, 2005.