4 HIA Methodology

4 HIA Methodology

4.1 HIA Process

A staged HIA process is outlined in Health Scotland’s Guidance on Health Impact Assessment of Transport Projects (Health Scotland, 2007). This HIA has followed this process, as outlined in Table 2 below.

Table 2: Staged Approach to HIA

HIA Stage

Key Tasks



Decide whether to do an HIA

Transport Scotland identified the need for HIA at an early stage to ensure recognised best practice was followed.


Set up the geographical, population and time boundaries over which to predict impacts and identify affected population groups

A review was undertaken of environmental and engineering assessments during route corridor option appraisal. This allowed an initial identification of the scope of the HIA. The scope was refined during the ongoing design development and consultation process.

Local profile

Collate relevant data on the local populations and features of the local area

Available published data were collated to prepare a population profile (see Section 5).

Involve stakeholders

Consult with local people and other stakeholders to identify their views on possible impacts

Health sector stakeholders were consulted and the HIA was informed by responses to consultation and engagement activities.

Identify and assess impacts

Identify the likely health impacts from the proposal. Carry out further review if this would help make recommendations

See Sections 6 to 11 of this report.

Make recommendations

Use findings to recommend measures that would improve health outcomes

This HIA Report refers to mitigation identified in the ES and recommends further measures as appropriate.

Monitor impacts

Monitor actual impacts that arise after the implementation of the proposal

To be taken forward by Transport Scotland at appropriate times during and after construction.

4.2 Scope of HIA

4.2.1 Nature of the Proposed Scheme

The proposed scheme is basically transferring general road traffic from the Forth Road Bridge crossing the Forth to a replacement crossing some 300m upstream, with public transport and pedestrian use on the existing bridge being maintained and enhanced.

Although the proposals do result in some changes to the population affected by the proposed scheme, this is only evident at a fairly detailed level. Fundamentally the same local populations that would be affected by the proposed scheme are affected by the existing road network.

One important aspect of the proposed scheme is that the existing crossing, the Forth Road Bridge, may not continue to function as a viable crossing without major repair.

The most recent focus of concern in relation to the Forth Road Bridge being able to continue to provide an unrestricted crossing has been the condition of the main suspension cables upon which the stability of the bridge depends. Internal inspection of the main suspension cables between 2004 and 2008 have reported that the main cables are estimated to have lost 10% of their strength. On that basis, and assuming that this rate of deterioration continues, restrictions to HGV traffic may be required at some point between 2017 and 2021 unless current preventative measures are successful.

4.2.2 Do-Minimum Scenarios

The ES has been undertaken on the basis of a Do-Minimum (i.e. the situation in the absence of the proposed scheme) scenario comprising the continued use of the Forth Road Bridge. Given that, in the absence of the proposed scheme, major works comprising cable replacement or augmentation works would be required in order for the Forth Road Bridge to remain operational, a supplementary assessment of impacts associated with these works was also carried out and reported as part of the ES. Full or partial closure of the Forth Road Bridge for the duration of these works would have severe impacts on the local transport system and economy.

For consistency, and unless otherwise stated, the ES Do-Minimum scenario is assumed as the basis for comparison within the HIA. Where relevant the effects of the proposed scheme are also qualitatively compared against the potential effects of the Forth Road Bridge maintenance works.

4.2.3 Scope and Level of Detail

As noted above, the proposed scheme is unlikely to give rise to impacts affecting very different populations compared to those affected by the existing road network.

It was not considered appropriate or relevant to undertake HIA at the level of detail required to capture fine changes and focus on very small discrete geographical areas. However, the HIA can very usefully capture the possible health impacts of the proposed scheme when compared to the scenario of the existing bridge being unfit to continue as a viable unrestricted crossing. The focus of this HIA therefore tends to be on the larger scale effects which can more confidently be described. The relevant determinants are described in the following section.

4.2.4 Health Determinants

Issues that can influence health and wellbeing (termed ‘health determinants’) include changes to people’s environmental, social and economic conditions. The health determinants included within the scope of this HIA are listed below.

Economics and Employment

  • Regional economic effects associated with the maintenance of a key transport link.
  • Direct and indirect effects on local business and employment during the operation of the proposed scheme.
  • Effects of the construction of the proposed scheme on business and employment.

Air Quality

  • Changes in levels of nitrogen dioxide (NO2) and particulate matter (PM10) resulting from changes in traffic movements.
  • Contributions towards greenhouse gas emissions.
  • Dust and emissions associated with the construction process.


  • Changes in noise levels resulting from changes in traffic movements.
  • Noise and vibration during construction.

Access to Services and Facilities

  • Changes in the accessibility of services and local community facilities, via cycle and pedestrian routes, car and public transport.

Social Capital

  • Effects on people’s ability to maintain social networks, resulting from changes in travel opportunities, severance and environmental effects.

Green Space and Physical Activity

  • Effects on public footpaths and cycle paths.
  • Effects on public open space (including designated areas such as public parks as well as informal amenity areas).
  • Accessibility and quality of leisure and sports facilities.

This HIA does not address occupational health and safety issues in relation to the construction and operation of the proposed scheme. The Health and Safety Plan for the proposed scheme would provide actions to ensure all relevant health and safety issues are addressed.

The effects of the proposed scheme on road safety are discussed in Section 6.4 of the DMRB Stage 3 Scheme Assessment Report (Jacobs Arup, 2009b) and are not addressed in this HIA.

4.2.5 Geographic Scope

Health effects of the proposed scheme are likely to be limited to within the following areas:

  • the local areas directly affected by the physical infrastructure of the Main Crossing, approach roads and other works; and
  • the wider region of Fife, West Lothian and Edinburgh, which would experience economic and transport related effects.

This assumption is based on the outcome of the Traffic and Economic Assessment , reported in the DMRB Stage 3 Scheme Assessment Report (Jacobs Arup, 2009b), and also on the assessed areas of impact for relevant environmental impacts such as noise and air quality, as reported in the ES.

4.2.6 Health Inequalities

Different groups within a community would experience the beneficial and adverse effects of an intervention in different ways. There is evidence for this in relation to socio-economic class and transport initiatives. For example:

  • Those in higher income groups are more likely to own a car and are therefore more likely to benefit from road infrastructure investment projects.
  • Those in lower income groups are more likely to suffer the adverse effects of traffic, including road traffic accidents, and are more likely to live in areas blighted by traffic noise and poor air quality.

HIA considers the potential disparities in impact between people in different socio-economic groups as well as other vulnerable groups such as children, the elderly and those with disabilities (see Section 6.2.3).

4.3 Evidence Linking Health Determinants with Health Effects

Utilising available literature, including previous health studies and recent research, an evidence base has been collated to identify links between the health determinants and health effects. Effects may be direct or indirect and links may be causal or compounding. Key reference material has included:

  • government health policies, programmes and strategies;
  • previous health impact assessments;
  • indicators developed by the London Health Commission; and
  • research undertaken by the NHS, Medical Research Council and other organisations.

A review of available relevant research and evidence of the health effects associated with each health determinant is summarised as appropriate within the relevant sections of this HIA. Where the evidence base contains gaps, it should be noted that an absence of or insufficient evidence does not constitute evidence of no link between the determinant and health effects. The degree of certainty in the assessment reflects the availability of evidence for a health link.

4.4 Baseline and Population Profile

Baseline conditions for health determinant were largely drawn from other assessments undertaken for the proposed scheme, including the ES (Jacobs Arup, 2009a) and the DMRB Stage 3 Scheme Assessment Report (Jacobs Arup, 2009b).

A profile of the population affected by the proposed scheme has been drawn from published data sources including:

  • the Scottish Index of Multiple Deprivation (SIMD);
  • Community Health Profiles (NHS Health Scotland);
  • Scottish Public Health Observatory (ScotPHO);
  • Scottish Transport Statistics;
  • Scottish Household Survey; and
  • Information Services Division Scotland (ISD).

The purpose of this exercise is to provide information on the social and health status of the affected communities, and to identify any issues that may be relevant to the assessment, such as:

  • vulnerable groups that may be disproportionately affected (either positively or negatively) by the proposed scheme;
  • links between health and social deprivation in the affected population;
  • links between health and transport/access issues in the affected population; and
  • health issues that could be improved or impacted by the scheme (e.g. levels of physical activity).

4.5 Stakeholder Involvement

Consultation was undertaken with the Public Health Directors at NHS Lothian and NHS Fife during the preparation of the HIA Report.

Responses received from the public consultations for the proposed scheme were reviewed in order to obtain information on the issues of concern to local communities and summarised in the Forth Replacement Crossing Public Information Exhibitions: Feedback and Outcomes Report prepared by Transport Scotland (2009a).

A separate report setting out Transport Scotland’s commitment to encouraging public interest and involvement will be reported in the evolving Consultation & Engagement Report (Transport Scotland, in press).

4.6 Impact Assessment

4.6.1 Effects on Health Determinants

The HIA has utilised information from a number of other assessments undertaken for the proposed scheme. Table 3 identifies the sources of information for each health determinant.

Table 3: Application Documents Relating to Health Determinants

Health Determinant

Relevant Documents

Economics and employment

DMRB Stage 3 Scheme Assessment Report

  • Part 2: Engineering, Traffic and Economics

DMRB Stage 3 ES

  • Chapter 7 - Land Use
  • Chapter 19 - Disruption due to Construction
  • Appendix A5.1: Supplementary Do-Minimum Assessment

Air Quality

DMRB Stage 3 ES

  • Chapter 15: Air Quality
  • Chapter 19: Disruption due to Construction
  • Appendix A19.1: Code of Construction Practice


DMRB Stage 3 ES

  • Chapter 16: Noise and Vibration
  • Chapter 19: Disruption due to Construction
  • Appendix A19.1: Code of Construction Practice

Access to services and facilities

DMRB Stage 3 Scheme Assessment Report

  • Part 2: Engineering, Traffic and Economics

DMRB Stage 3 ES

  • Chapter 17: Pedestrians, Cyclists, Equestrians and Community Effects
  • Appendix A5.1: Supplementary Do-Minimum
  • Appendix A19.1: Code of Construction Practice

Physical Activity and Green Space

DMRB Stage 3 Scheme Assessment Report

  • Part 2: Engineering, Traffic and Economics

DMRB Stage 3 ES

  • Chapter 17: Pedestrians, Cyclists, Equestrians and Community Effects
  • Chapter 12: Landscape
  • Chapter 13: Visual
  • Chapter 16: Noise and Vibration

Social Capital

DMRB Stage 3 ES

  • Chapter 17: Pedestrians, Cyclists, Equestrians and Community Effects

4.6.2 Assessing Health Effects

Conclusions on the potential impacts on health and wellbeing effects are based on available research demonstrating causal links between environmental and socio-economic factors and health (see Section 4.3). It should be noted that the existence of a causal link between a particular factor and health does not necessarily mean that changes in such a factor caused by a road scheme will produce a health effect.

Changes in population health have a wide and complex range of contributory factors many of which are likely to be unrelated to the proposed scheme. The purpose of the assessment is to identify where improvement or worsening of health determinants is likely to take place, and qualitatively assess the implications of these changes for the health and wellbeing of the affected individuals or communities.

The significance of potential health effects was assessed using a system based on the criteria described in the Merseyside Guidelines for Health Impact Assessment (Liverpool Public Health Observatory, 2001). This system involves the classification of effects in three different ways:

  • determining the nature of the impact (classified either as positive or negative);
  • assessing its measurability (defined on a three point scale of qualitative, estimable or calculable); and
  • estimating the degree of certainty in the assessment using the terms speculative, probable and definite as described below:
  • speculative effects occur where either the causal link between the determinant and the health effect is unproven; or linkages between the determinant and health effects have been established but action is required to bring about the potential health effect;
  • probable effects are those where causal linkages between the determinant and health have been established and where the effects do not require individuals or organisations to take a particular course of action; and
  • definite effects are those which are considered to be inevitable – this term is not utilised in this study.

In addition to the Merseyside criteria above, the following categories have been used to describe the magnitude of health effects arising:

  • Negligible: where any health effects are expected to be too small to measure;
  • Minor: where it is considered likely that the health or wellbeing of isolated individuals would be mildly affected;
  • Moderate: where it is considered likely that the health or wellbeing of a proportion of the community would be mildly affected, or isolated individuals would be particularly affected; and
  • Major: where it is considered likely that a proportion of the community would be significantly affected.

The Guidelines note that definite, quantifiable effects are not necessarily more important in the assessment than speculative and qualitative effects.

4.7 Mitigation

Mitigation from the ES which is relevant to the HIA has been summarised in this report and these mitigation measures have been taken into account in the consideration of health impacts. Where appropriate, further HIA-specific mitigation to reduce adverse health effects and, where possible, improve health outcomes has been identified as a result of the HIA findings. Transport Scotland has reviewed the HIA-specific mitigation measures in this report and is committed to their implementation.

4.8 Limitations and Assumptions

Consultation has been limited to correspondence and meetings with stakeholders within the health sector. Public consultation has not been undertaken specifically for the HIA, although feedback from the consultation and engagement activities has informed the appraisal.

Baseline data on health and socio-economic conditions are limited to publicly available data. Local level data have been used wherever possible. However in many cases information is only available at the national or regional level.

Commentary level assessment has been provided on the effects of the proposed scheme on vulnerable groups. More detailed assessment of these impacts has been limited by a lack of available data on the presence of vulnerable groups within the study area.