The speed limit on Oxford's ring-road (excepting the A34 outside Botley) should be reduced to 40mph and that should be enforced by average speed cameras. This would help with road danger, congestion, community severance and barriers to walking and cycling, noise pollution, air pollution, and carbon emissions.
Enforcement of the existing speed limits would help. Measurements at Barton Park found nearly half of all vehicles on the A40 exceeding the 50mph speed limit (the average speed was 49mph).
One interesting comparison: Paris' Boulevarde Peripherique is currently 70km/hr (43mph) and there are plans to drop it to 50km/hr (31mph).
- Lower speeds would mean fewer vehicle collisions and less serious ones, which would reduce deaths and serious injuries and also reduce congestion resulting from collision-driven road or lane closures.
- Lower speeds would make at-grade crossings safer and more accessible. There are obvious examples at Barton Park and Kiln Lane, but there are many less obvious crossings at-grade whose safety and usability would be greatly improved by lower speeds. It is notable that the Wolvercote and Cutteslowe roundabouts and the A40 between them already have 30mph speed limits.
- Lower speeds would significantly reduce noise pollution and its adverse affects on health. This would benefit large areas of the city, since background noise from the ring road extends a long way, but would particularly benefit areas such as Rose Hill, Littlemore, Wood Farm and Barton, which are among the areas of Oxford with the poorest health.
- Keeping speeds below 50mph would reduce carbon emissions and air pollution.