Scheme Appraisal for Highway Projects 69Economy
The degree to which the proposal contributes both to economic efficiency and
to sustainable economic growth in appropriate locations is assessed under this
heading. A discount rate of 6% and a base year 1994 are again utilised for indi-
cators assessed in monetary terms. Four indicators are used, as follows.
Journey times and vehicle operating costs
The effectiveness of the proposal on this criterion is measured in terms of the
monetary value, in present value terms, of the reductions in both journey times
and vehicle operating costs brought about directly by the construction of the
new/improved road.
Costs
The present value of the costs of construction net of the cost of construction
of the ‘do-minimum’ option.
Reliability
This assesses the impact of the proposal on the objective of improving the
journey time reliability for road users. Reliability is reduced as flows reach capac-
ity and stress levels increase. Stress can be defined as the ratio of the AADT to
the congestion reference flow (CRF), expressed as a percentage. (CRF measures
the performance of a link between junctions.) Reliability is not an issue for stress
levels below 75%, with 125% as the upper limit. The assessment is based on the
product of this percentage and the number of vehicles affected. The difference
in stress for the old and new routes should be estimated. The final assessment
is based on the product of flow and the difference in stress. Values in excess of
+/-3 million are classified as large (positive or negative),+/-1 to 3 million
classified as moderate,+/-0.2 to 1 million classified as slight and values less
than 0.2 million classified as neutral.
Regeneration
This evaluates whether the proposal is consistent with government regeneration
objectives. The final assessment is a simple yes/no to this question, based on the
extent to which the road is potentially beneficial for designated regeneration
areas and on the existence of significant developments within or near regener-
ation areas likely to depend on the road’s construction.
Accessibility
This criterion relates to the proposal’s impact on the journeys made within the
locality by modes of transport other than the private car, assessing whether the
proposed project will make it easier or more difficult for people to journey to
work by public transport, on foot, by bicycle or other means.