Distributional Impact report – DfT feedback
Scheme: NNDR – A140 option
Summary: In some places, there is evidence of confusion about the DI scoring system. Page
2 of the A140 option report describes the scoring system applied as: “Social groups that
have impact area proportions that are […/larger/in line/smaller…] than the national average”.
However, in general the DI scoring system is intended to highlight where the proportion of
people impacted is larger / in line / smaller than the proportion of that group in the impact
area. The impact of this is shown in the first indicator (see below).
Generally, it would be helpful for drawings currently in the appendix to be presented in the
main body of the report. It would also be helpful if fuller justifications on limiting the analysis
to particular areas or social groups, or not assessing amenities were presented.
It appears that the appraisal table incorrectly analyses the distributional impacts of that
indicator, by assessing the proportion of a deprived group against the national average. The
row labelled ‘population’ in Table 2.2 seems to be incorrectly labelled, and instead to be the
share of user benefits as a proportion of the total user benefits. The analyst has then
compared that against the national average (which by definition will be 20% nationally for
income quintiles) to arrive at a score. The analysis presented here seems to incorrectly
follow the guidance.
The correct application is to compare the share of the user benefits (as a percentage)
against the share income distribution within the impact area. No reference to the national
average is needed (see Table 7, page 16 of WebTAG A4.2).
As mentioned above, a fuller justification of no amenities being considered could be
If, as Table 3.3 suggests, there are no most-deprived quintiles within the noise impact area
then a score should not be applied. As above, the proportion of those impacted should be
compared with the proportion within the impact area. Table 3.3 should include (as per Table
9 in WebTAG A4.2) a full breakdown of those affected across each income quintile.
The analysis presented in 4.3 and 4.4 is appropriate, however the analyst may wish to
reconsider their summary of this analysis. Each income quintile should be summarised on
the basis of their overall share of impacts compared to their proportion in the impact area
(note that 4.4.11 in WebTAG A4.2 comments on summarising results from both PM10 and
On which links / junctions are accident reductions expected at? At which are they expected
to increase? In which areas are the greatest increases / decreases? What is the nature of
the current accident profile?
Very little attempt has been made to assess the locations or likely movements of vulnerable