California has been the epicentre for the fight against global warming state side, having set a target to reduce greenhouse gas emissions to 1990 levels by 2020 – and to 80 per cent below these levels by 2050.
However, now new figures suggest these targets may be unobtainable.
The California Air Resources Board estimates that sufficient reductions in greenhouse gas emissions from passenger vehicles can be achieved through improvements in vehicle technology and the low carbon fuel standard – however, this will not be enough to achieve 1990 levels if current trends in vehicle miles travelled continue.
Dr Caroline Rodier of the UC Davis's Institute of Transportation Studies reviewed international modelling literature on land use, transit and auto pricing policies and suggested a range of both vehicle miles travelled and greenhouse gas emission reductions that might be achieved if such policies were implemented.
Over a 10-year time horizon she believes that the following policies can lead to the reductions outlined:
- Employee parking pricing may result in a one per cent reduction in vehicle miles travelled;
- Pay-as-you-drive insurance can bring reductions from four-five per cent.
- Cordon pricing schemes could reduce vehicle miles travelled by two-three per cent.
- Increased transit investment may reduce miles travelled by 0.1-one per cent.
- Land-use only scenarios may cut vehicle miles travelled by up to two per cent.
- Land use and transit scenarios may reduce vehicle miles travelled by two-six per cent over the 10-year time horizon.
- Combined land use, transit and pricing policy measures could bring significantly greater reductions.
In all she notes that even improved calibrated travel models are likely to underestimate vehicle miles reductions from land use, transit and pricing policies