Why Coordinate the Development of New Transport Systems?

Sitting on the train between Sweden and Denmark crossing the Öresund bridge, which was inaugurated in 2000, it seems relevant to think about the need to coordinate the development of new transport systems.

If it would be more efficient to allow the market to determine which technologies to use for future road transport, why did not the same thought occur to decision makers when decisions were made to build the Swedish/Danish system or the UK/French system that connects these two countries via the tunnel? Governments could have allowed different contractors in the two countries in each case to build the systems they wanted and different alternatives could have competed for the prominence in each country. This could have led to a situation where travelers would have to change trains on the bridge or in the tunnel, moving between the systems preferred on each side.

The comparison is relevant. The primary difference between trains and road transport is that trains move on tracks and it seems obvious that the same tracks need to continue into another region or country if we want to maintain efficient communications. But road transport systems also need very costly infrastructure and vehicles and these systems also need to extend between regions and countries, far beyond the borders of Sweden or Denmark. People travel and we import goods and that are transported on trucks. We cannot leave vehicles behind at the border only to change to other vehicles that are compatible with the fuel systems, filling stations, and charging posts of the country or region we travel to.