Invest in public transport or build new roads?

Traffic congestion is one of the biggest problems of modern cities. Some people believe that governments should spend their money on public transport, while others think that building new roads is a better solution. In this essay I will discuss both opinions before giving my own.

On the one hand, there are many advantages to investing in public transport. Buses and trains can carry a large number of passengers at the same time, so there are fewer cars on the streets. Public transport is also cheaper for ordinary families, especially for students and old people, and it produces less pollution than private cars, which is better for the environment and for our health. Furthermore, in many big cities the metro is much faster than driving during rush hour.

On the other hand, some people argue that new roads are necessary. When a city grows, the old roads become too narrow for the number of cars, and this causes long traffic jams every morning and evening. New roads and bridges can also connect villages to cities, which helps the economy and allows people to travel more easily. In addition, some places are too far away to be served by buses or trains. For instance, in my own country there are many small villages in mountain areas where no company would ever run a bus service, and for the families living there a good road is the only realistic way to reach a hospital or a university in the nearest city.

In my opinion, governments should invest in public transport, because it is cheaper, cleaner and can move more people than private cars.

The choice between building roads and funding transit looks like a question about money, but it is really a question about a single well-documented mechanism, and once that mechanism is on the table the two positions are no longer symmetrical. My view is that transit should take priority, with roads justified only where transit cannot physically serve the journey.

The road argument is not naive, and it is strongest away from city centres. Freight moves on roads and will continue to; a region of scattered villages cannot support the density a bus network needs; and a bypass that removes lorries from a town centre improves that town immediately and permanently. Dismissing road building wholesale ignores the journeys no train will ever make.

Within cities, however, road building fails on its own terms because of induced demand. Additional capacity lowers the effective cost of driving, which draws in journeys that were previously made at another time, by another route, or not at all, until congestion returns to roughly its former level — typically within a few years. This is not a marginal effect; it is the ordinary outcome, and it means the money buys a temporary improvement and a permanently larger road. Transit is not immune to demand either, but when a metro line fills up the result is a full metro line, not a jammed one.

The caveat is that this only holds if the service is good enough to be chosen rather than endured. A bus every forty minutes does not compete with a car and never will. So: fund transit at frequencies that make it a genuine option, price road space honestly, and build new roads where geography leaves no alternative.