Environmental Impact Assessments


Environmental Impact Assessment

An Environmental Impact Assessment (EIA) is a means of systematically drawing together the assessment of the likely significant environmental effects arising from a proposed project. The EIA process provides a valuable opportunity to reduce potential environmental impacts through design refinement and is undertaken as an integral part of Transport Scotland’s design process. Environmental constraints and issues are identified through consultation, extensive environmental surveys and technical assessments. The information gathered can then inform the decision-making throughout the design process, providing opportunities to address potentially significant impacts at an early stage, for example by refinement of route alignment or by the incorporation of mitigation measures into the proposed Scheme design. Impacts are then assessed by comparing the existing situation (the baseline conditions) to the conditions that would occur with the proposed Scheme in place.

The formal requirement for EIA of Trunk Road projects is set out in the Roads (Scotland) Act 1984.

The EIA Directive (2014/52/EU) was transposed into Scottish law in May 2017. The relevant regulations in Scotland for motorways and trunk roads are The Roads (Scotland) Act 1984 (Environmental Impact Assessment) Regulations 2017 (SSI 2017 No.137). The EIA Regulations amend the Roads (Scotland) Act 1984 (as amended).

The EIA Regulations categorise developments according to their requirement for an EIA. Annex I lists large-scale or potentially high impact developments for which an EIA is always required. Annex II lists developments that may or may not require an EIA depending on the characteristics and location of the development, and the significance of potential effects.

All projects and maintenance works undertaken on the trunk road network are screened for environmental effects by environmental specialists with relevant expertise or qualifications to ensure that the legislative and statutory requirements for EIA are met.

Scottish Ministers under the EIA legislation must determine if a project falls within Annex I or Annex II.

Road projects that fall under Annex I include:

  • Construction of motorways and express roads
  • Construction of a new road of four or more lanes, or realignment and/or widening of an existing road of two lanes or less so as to provide four or more lanes, where such new road or realigned and/or widened section of road would be 10 km or more in a continuous length

Under Annex II, a ‘relevant’ project is screened to determine if it is an improvement or maintenance scheme which meets the following criteria:

The completed works, including construction works and any area occupied by apparatus, equipment, machinery, materials, plant, spoil heaps or other such facilities or stores required during the construction period:

  • Exceed 1ha in area, or
  • Are situated in whole or in part in a sensitive area

For Annex I and II projects, a Record of Determination will be prepared which provides evidence and information for the determination and includes the main potential effects on the environment and mitigations to be implemented that will minimise the environmental impact. The record and notice of the works is published in the press. Where a full EIA is required, the Record of Determination helps to inform the screening and scoping process.


This Guidance Note provides Transport Scotland’s advice on the key statutory requirements for environmental impact assessment (EIA) for road projects. This is not intended to be a complete guide to EIA, but provides the principal stages where Transport Scotland has statutory obligations. It also provides some advice on non-statutory environmental assessments.

Transport Scotland’s Review

Transport Scotland reviews Environmental Statements (ES) with regard to the potential environmental impacts associated with increased development traffic on the Trunk Road and its adjacent receptors (such as communities) in line with the Guidelines for the Environmental Assessment of Road Traffic (Institute of Environmental Assessment).

The impact of traffic is dependent upon a wide range of factors including: volume of traffic, traffic speeds and operational characteristics and traffic composition. Additionally, different types of development will attract different levels and types of traffic, therefore, different environmental impacts.

The review process focuses on any direct physical impacts and on the environmental effects associated with increased traffic on the Trunk Road network and includes consideration of the following effects:

  • accidents/safety
  • severance
  • pedestrian/cycle amenity
  • pedestrian delay
  • driver delay
  • infrastructure wear and tear
  • noise and air quality

The most common issues associated with EIA projects are:

  • requests for new junctions onto the Trunk Road network or to use the network for the movement of abnormal loads; for example in the case of a quarry or wind turbine application.  In such circumstances, we ask the applicant to provide the design of any proposed alteration to the Trunk Road or for a Route Assessment report in the case of transporting abnormal loads.
  • environmental effects associated with increased traffic. The focus here is to establish the significance (in accordance with the environmental regulations) of the effects and consider the appropriateness of any mitigation measures.
  • noise & vibration and air quality impacts, which are dealt with under PAN 1/2011 Planning and Noise and the Design Manual for Roads and Bridges For further information on the assessment of the environmental impact of road traffic associated with new developments please see the Guidelines for the Environmental Assessment of Road Traffic (Institute of Environmental Assessment).

We welcome early discussion on EIA requirements.