The bus-train from Liverpool to Cambridge (UK) whines quietly by at 90 mph. The journey of 192 miles will take under three hours, faster than trains or cars. It operates under computer control while the staff on board spend their time serving meals and coffees. 120 passengers enjoy the ride, watching TV and arriving relaxed. It uses roads that were built in the last century, with minor changes at junctions to accommodate these large vehicles.  There are no traffic queues because most people chose to use public transport rather than private cars.

The bus is electrically powered and its energy consumption per passenger is less than a tenth that of a diesel car. Its small energy consumption is consistent with the use of renewable energy sources, so it is effectively zero-carbon.

Across the world, bus-trains operate where there are no direct railway lines. On other routes they compete with trains and provide pressure to reduce ticket prices and improve services. They stop at new bus stations at the side of major roads. People use local buses, trams, trains or short-range electric cars to access these stations.

Why can’t this be done now? It is already starting to happen. Long-range electric buses have already been developed and will become more practical as batteries and fuel cells improve. Batteries can be used for buses for journeys of up to perhaps 200 miles, hydrogen fuel cells will permit longer ranges.

Articulated or bendy buses are already common in many cities, and fast articulated buses have been built. Buses are becoming more luxurious, for example some recent  buses have are fitted with personal entertainment systems and internet access.

Automatic control is being demonstrated for cars, and computer control should be easier for buses that follow simple routes on major highways. The system will cut operating costs and allow long journeys without rest breaks. By 2050 automatic control may be mandatory to cut the risk of human error and to provide a rapid and predictable response to problems.

What is needed technically is simply accelerated development and testing to set safety standards. There will also be a need for politicians to change legislation,  provide incentives, and make the required infrastructure changes. Finally there will be a need for personal tax changes to ensure that excessive use of fossil fuels is prevented, since that will drive the use of low energy systems such as this.