8 Aug 17

Self-drive cars could make traffic worse – here's how to prevent it

Here is the coming mobility revolution in a nutshell: electric, autonomous, shared. Congestion: solved. Planet: saved. But a recent study warns that unless we actively choose the best-case scenario, there is still plenty of scope for things to go wrong.

The central problem is the two visions competing for the future of mobility. On the one hand, 'urbanists' aiming to shift the focus from single-occupied cars to multimodal transport, freeing up space for other purposes than traffic. On the other, 'ecologists', who want to reduce harmful emissions by weaning our vehicles off fossil fuel, replacing them with alternative powertrains (increasingly the consensus is on electric).

While in theory these two visions could perfectly overlap and merge in the future, that is not necessarily going to happen in practice, warns a study by the University of California – Davis and the Institute for Transportation and Development Policy. Entitled Three Revolutions in Urban Transportation, it sketches three different scenarios for mobility between now and 2050:

→ Business As Usual (BAU)
The use internal combustion engines continues to increase, public transport and shared vehicles are used at the current rate, population and traffic grow as projected.

  • Number of vehicles on the road: 2.1 billion
  • CO2 emissions: 4,600 megatonnes

→ Two Revolutions (2R)
Electric vehicles are common by 2030, automated vehicles by 2040. But single-occupancy vehicles remain the norm, leading to 10-15% more traffic than today.

  • Number of vehicles on the road: 2.1 billion
  • CO2 emissions: 1,700 megatonnes

→ Three Revolutions (3R)
As in 2R, but with a maximisation of shared mobility: ride-sharing is widespread by 2030, transport is increasingly on-demand, infrastructure is redesigned to benefit walking and cycling.

  • Number of vehicles on the road: 0.5 billion
  • CO2 emissions: 700 megatonnes

In the 2R scenario, CO2 emissions are drastically reduced, but traffic increases nonetheless, because autonomous vehicles can travel without their single occupant (e.g. to drop them off or pick them up). While the ecology benefits, the urbanist goal of freeing up space is actually further away than it is now.

Only in the 3R scenario are the beneficial effects of electrification and automation amplified by the application of the sharing principle. Here, the dramatic reduction in the number of vehicles on the road further reduces the amount of CO2 emitted by traffic. Both 'urbanist' and 'ecologist' goals are fully achieved.

However, while the 3R scenario is the one with the best results, it is also the hardest one to achieve – requiring the highest amount of policymaking: regulate individual car ownership, develop shared alternatives, and build appropriate public transport options.

The study suggests what would be a right mix for an ideal 3R scenario: high-capacity, fixed-route rail and buses, with additional shared, on-demand AEVs (autonomous electric vehicles) that range from single-seater pods to 18-seater buses.

Image: Institute for Transportation and Development Policy

Authored by: Frank Jacobs