Scheme Appraisal for Highway Projects 63(1) A physical description of the project
(2) A description of measures envisaged to reduce/remedy the significant
adverse environmental effects of the project
(3) The data required to both identify and assess the main effects on the envi-
ronment of the project in question.
Within the UK, since 1993 the Design Manual for Roads and Bridges(DoT,
1993) has provided the format within which the environmental assessment of
highway schemes has taken place. It identified 12 environmental impacts to be
assessed for any new/improved trunk road proposal. These, together with the
economic assessment, would form the decision-making framework used as the
basis both for choosing between competing options for a given highway route
corridor and for deciding in absolute terms whether the proposal in any form
should be proceeded with.
The 12 environmental impacts forming the assessment framework are:
Air quality The main vehicle pollutants assessed are carbon monoxide
(CO), oxides of nitrogen (NOX) and hydrocarbons (HC), lead (Pb), carbon
dioxide (CO 2 ) and particulates. Established models are used to predict future
levels of these pollutants, and the values obtained are compared with current
air quality levels.
Cultural heritage The demolition/disturbance of archaeological remains,
ancient monuments and listed buildings and the impact of such actions on
the heritage of the locality, are assessed under this heading.
Construction disturbance Though this impact is a temporary one, its effects
can nonetheless be severe throughout the entire period of construction of
the proposal. Nuisances such as dirt, dust, increased levels of noise and
vibration created by the process of construction can be significant and may
affect the viability of the project.
Ecology/nature conservation The highway being proposed may negatively
affect certain wildlife species and their environment/habitats along the route
corridor in question. Habitats may be lost, animals killed and flora/fauna
may be adversely affected by vehicle emissions.
Landscape effects The local landscape may be fundamentally altered by the
construction of the proposed highway if the alignment is not sufficiently
integrated with the character of the local terrain.
Land use The effects of the route corridor on potential land use proposals
in the area, together with the effects of the severance of farmlands and the
general reduction, if any, in general property values in the vicinity of the
proposed route, are assessed under this heading.
Traffic noise and vibration The number of vehicles using the road, the per-
centage of heavy vehicles, vehicle speed, the gradient of the road, the pre-
vailing weather conditions and the proximity of the road to the dwellings
where noise levels are being measured, all affect the level of noise nuisance