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2.3.3 stage c: assessing the effects of the plan
Predicting the effects of the plan and evaluation of effects
Authorities should seek to predict and evaluate the effects of elements of the
evolving plan – options, policies, proposals and revisions – while they are work-
ing on them. Where adverse effects are seen to be likely, possibilities for mitiga-
tion should be considered. Aspects of Stage C may need to be carried out more
than once in the course of a plan’s development:
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Identifying the changes which are predicted to arise from the selected sce-
nario, in comparison to “no plan” or “business as usual” scenarios.
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Describing these changes in terms of their magnitude, their geographical
scale, the time period over which they will occur, whether they are perma-
nent or temporary, positive or negative, probable or improbable, frequent or
rare, and whether or not there are cumulative and/or synergistic effects.
Predictions do not have to be expressed in quantitative terms. Hard data may en-
able planning authorities or expert advisers to make detailed quantitative predic-
tions, and this can be particularly useful where the plan’s effects are uncertain,
close to a threshold, or cumulative.
But quantification is not always practicable, and broad-based and qualitative
predictions can be equally valid and appropriate. As in current practice, these
may be expressed in easily understood terms such as “getting better or worse”
or a scale from ++ (very positive) to -- (very negative).
Assessment methods
In order to evaluate the degree of consistency (to reckon different levels of inter-
action/interference) of the selected Scenario (and of the Action Plan stemming
from it) with the values recognized and some options expressed by planning
