Sub-Criteria
Environmental Impact
Noise
Local Air Quality
Landscape
Biodiversity
Heritage
Water
Economy
Journey times and Vehicle Operating Costs
Journey Time Reliability
Scheme Costs
Regeneration
Accessibility
Access to Public Transport
Community Severance
Pedestrians and Others
Integration
* None
For each of these, the impacts of a road scheme are expressed in the following ways:
qualitatively - using words to describe the main impacts;
quantitatively - using numbers to measure the scale of the impacts; and
as a summary assessment - using either a monetary value, a quantitative indicator or a textual ranking.
The next page shows the AST for the congestion relief scheme for the A3 at Hindhead. Where monetary values cannot be estimated the following seven point scale is used.
large negative;
moderate negative;
slight negative;
neutral;
slight positive;
moderate positive;
large positive.
An additional ranking, very large negative, has been used where environmental impacts were deemed to be exceptionally severe. A scale in words rather than numbers has been used to avoid implying a direct comparison between types of impact which are not directly comparable.
Eddington and beyond
The Eddington Report shows that more work is going on to improve on AST. Ultimately all social costs and benefits should be monetized and included. Presently there is not enough data to do this. (To get monetary values there must be clear evidence from schemes actually enacted to judge these monetary values. Especially when valuing environmental effects this evidence simply does not exists.)
The section below gives the various measures used by the Eddington Report. Some extend beyond AST.
Government policy
There has been a major change of emphasis in government roads policy. This can be broadly split in to three.
Up to 1994, 1994 to 2000 and 2000 onwards.
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