To understand the transport system we need to think in terms of the major groups of users, and the problems they cause. We need to get out of the mentality of developing the networks on a who-shouts-loudest basis.
Every day, people in cities travel in complicated patterns that almost defy comprehension. Transport models attempt to reproduce this pattern, to allow us to test the effect of changes to the system. But the sheer complexity makes these models unwieldy, and prone to misinterpretation. The modellers do their best, but there’s a huge gulf in understanding between policy-makers and modellers.
Instead of really understanding the transport system, policy-makers focus on the separate networks (the roads, the trains, buses, bikes), their problems, and try to fix them. In fact it is quite normal for the different networks to be managed by entirely separate policy-makers, who just promote investment in their own network. This failure to manage the networks as an inter-related system means that we never solve congestion.
So instead of thinking in terms of networks, I think we need to focus on the different groups of users. This is inevitably going to be a huge simplification, but I think it gives a good starter to understanding the system, and generates some important policy insights. To make it memorable, I’m going to divide the different users into five groups: Angels and Devils, Saints and Martyrs, and Mortals.
In terms of the system, the main impacts are from people who travel further, or whose trips are particularly concentrated in particular places or at particular times. So we start with the Angels. These are people who travel into the city centre by public transport (or on foot or by bike). These are economically-valuable trips and the people making them are doing so in an efficient manner with little impact on other travellers.
In contrast, the Devils are people who drive into the city centre. They almost all have a public transport alternative, but choose instead to inflict their transport choice on everyone else, taking a disproportionate amount of congested space. Driving to work in the city centre is even worse – these journeys are concentrated in the peak, causing severe congestion.
The third group are the Saints, and here we break from the usual narrative. There is a very strong divide between city centre destinations, where public transport is readily available (and fairly well used), and suburban destinations, where public transport is usually inconvenient, and almost everyone drives. People who work in the suburbs are making a valuable economic contribution, even if they are driving. A bit like saints performing miracles, while still being human, and sinners.
The fourth major group are the Martyrs. These are the people delivering freight. With the exception of some long-distance and bulk cargoes, almost all freight is moved by road. The logistics industry is very competitive, and very much focused on minimising overall costs. Freight is a key part of the economy, and there is not much choice about how it is distributed. So this group primarily suffers from congestion caused by others.
The last group are the Mortals. Lots of trips are quite short, well-dispersed and don’t really cause any problems. This includes almost all cycling and walking, but many short car trips in the suburbs too. To a first approximation, these trips are just background noise in the system. We might want to encourage cycling and walking for various reasons, but at a system level, they have little effect.
This high-level division of traffic into five groups is crude, but gives a basic structure for transport policy. If we want to tackle congestion, we have to focus on getting the Devils out of their cars and using public transport, or cycling or walking. But this isn’t a war on motorists: it’s entirely reasonable that the Saints and Martyrs drive. We need to be a lot clearer about which car journeys are a problem, and a lot more assertive about converting such trips. The aim should be to convert all of those Devils into Angels. In most cities, almost all of the congestion is due to the Devils.
Concentrations of Saints can still cause congestion, but it’s unreasonable to treat this as an individual problem. There will be particular congestion problems around hospitals and business parks. Here the solution lies with the planners: offices should generally be located in city centres, so that businesses can benefit from agglomeration effects, and staff benefit from access to shops and other amenities. Allowing, or even encouraging offices to develop in the suburbs or out-of-town locations will just lead to endless demands for more road capacity. Offices should be around public transport hubs, and suburban land used for housing instead.
Hospitals in suburbs or out-of-town locations can be very difficult to address, but the all-day travel demand can make for a viable public transport offer, if parking is restrained. This is probably a long-term project, so it’s good to get it into the plans. But it will be much easier to focus on the city centre in the first instance.
Sometimes looking at a complicated problem in a different way can make it a lot simpler. It’s not that public transport is good, and the car bad, but that the economy works best when high-density office jobs are concentrated in city centres, and people use public transport (or walk or cycle) to get to them. We should stop thinking in terms of promoting the alternatives. Instead we should actively suppress car use into city centres, and then provide public transport in response to the demand.