Project appraisal - Transport Policy and Planning in Great Britain - page 356

Box 21.1 DfT comparison of options for linking the A303 to the M5

Taunton

A358

M5

Blackdown Hills A303

A30

10 miles (approx)

Exeter

Honiton

A358 Option (dual carriageway improvement on existing alignment)

BCR is 2.80

The AST identifies a mix of impacts (beneficial, neutral and adverse) on non-
monetised issues, but none is described as being 'large'. Overall the value of the
adverse impacts is likely to more than outweigh the value of the beneficial impacts,
but these are not judged to be quite large enough to justify moving to a medium
VfM classification, i.e. they are estimated at being valued as less than 80% of the
scheme's costs.
The option is therefore high VfM.

A303/A30 Option (dual carriageway route on new alignment)

BCR is 2.35
The AST identifies a mix of impacts (beneficial, neutral and adverse) on non-
monetised issues. However few are assessed as beneficial and of these none is large.
On the other hand there are a number of large or moderate adverse impacts with the
impacts of landscape and biodiversity being described as 'very large adverse'. This
reflects the fact that three-quarters of the route lies within an AONB and that two Sites
of Special Scientific Interest are affected together with other considerable cumulative
effects on biodiversity.
On balance the non-monetised impacts identified in the AST are likely to be
severely negative. This would therefore reduce the VfM of this scheme below that
implied by the BCR. If the net cost of all the non-monetised impacts were valued at
£160m-£260m the scheme would be low VfM. If the net cost were valued at more
than £260m the scheme would be poor VfM.