Part 4: Traffic and Economic Assessment 19. Modelling 19.1 Introduction 19.2 Transport Model for Scotland 19.3 TMfS Representation of Baseline Conditions 19.4 Population and Employment Forecasting 19.5 Future Year Matrices 19.6 Do-Minimum Network 19.7 Do-Minimum Forecasts 19.8 Summary 19.9 References
Part 4: Traffic and Economic Assessment
19.1.1 The traffic and economic assessment of the alternative options proposed for the connecting road network required in conjunction with the proposed replacement bridge has been undertaken using the Transport Model for Scotland (TMfS:05A). This is a strategic, four stage, multi-modal forecasting model with a 2005 base year that translates output from the Transport and Economic Land Use Model of Scotland (TELMoS) into forecasts of travel demand on both the road and public transport networks.
19.1.2 TMfS:05A was used to compare alternative options in terms of performance indicators such as changes to traffic flows, speeds, journey times and travel distances. These outputs are then input to the Transport Users Benefit Appraisal (TUBA, v1.7) software to identify the economic benefits of each option compared to a do-minimum scenario. Output from TMfS:05A was also used in the environmental appraisal of options as discussed in Chapter 13 (Air Quality) and Chapter 14 (Traffic Noise and Vibration).
19.1.3 This section of the report describes the operation of the transport model and a review of its accuracy with regard to cross-Forth travel and future year forecasting. Chapter 20 (Effects of Route Corridor Options) summarises the primary effects of the corridor options considered. The economic performance of the various corridor options are presented in Chapter 21 (Economic Performance of Route Corridor Options).
19.2.1 The Transport Model for Scotland (TMfS:05A) is an enhanced version of TMfS:05, as used in the Forth Replacement Crossing Study as part of the Strategic Transport Projects Review (STPR) and reported in 2007. Both have a base year of 2005, and cover a geographical area that encompasses 95 per cent of the population of Scotland. They also include all of the principal urban centres (except Inverness), all Trunk Roads and a large proportion of non-Trunk principal roads. The model has been developed and maintained by MVA Consultancy (MVA) for Transport Scotland, for use as a planning and forecasting tool for projects such as this.
19.2.2 The main difference between these two versions of the transport model was the inclusion of modelled zones and public transport networks across the Highlands and Islands, alongside the incorporation of additional Origin – Destination travel data obtained through Roadside Interview (RSI) data in Ayrshire and around Dundee into the model calibration and validation process. Full details of TMfS model development and operation are available from www.tmfs.org.uk.
19.2.3 Road based travel demand is assigned to the highway network using a volume averaged all-or-nothing assignment, in passenger car units (pcu) for each of the following four vehicle classes:
- Cars (travelling in work time);
- Cars (travelling in non-work time);
- Light Goods Vehicles (LGV); and
- Other Goods Vehicles (OGV).
19.2.4 In addition, scheduled bus and coach services are coded to follow predefined routes based on operator timetables.
19.2.5 Model vehicle speeds are derived from speed-flow curves for each link type in the TMfS model. Junction delays are calculated for each movement at each modelled junction. Figures showing the extent of junctions that have been modelled are provided in the model calibration and validation reports on the TMfS website.
19.2.6 Three distinct one hour time periods are modelled. These are:
- 08:00 – 09:00 (AM);
- 1/6 of 10:00 – 16:00 (inter-peak); and
- 17:00 – 18:00 (PM).
19.2.7 Across the network as a whole, the 08:00 – 09:00 modelled hour is considered broadly representative of the morning ‘peak’ hour, while the 17:00 – 18:00 modelled hour is considered broadly representative of the evening ‘peak’ hour.
19.2.8 To assess traffic flows over other time periods (for example 18 hour average weekday and Annual Average Daily Traffic (AADT)), AM, inter-peak and PM flows are combined as follows:
- 18 hour weekday flow = 2.21 x AM flow + 8.61 x inter-peak flow + 2.58 x PM flow
- AADT flow = (560 x AM flow + 3419 x inter-peak flow + 651 x PM flow) / 365
19.2.9 These conversion factors were provided by MVA based on their analysis of Scottish Household Survey data. Factors were provided for both Scotland as a whole and disaggregated by Regional Transport Partnership (RTP) area. Resulting flow estimates, based on factors for the South East Scotland Transport Partnership (SEStran) area, were used in the environmental appraisal and for defining the proposed mainline carriageway standards.
19.2.10 Economic assessments required the use of default national factors (from TUBA guidance) to annualise the data as trips to and from other parts of Scotland were included in the assessment. The relevant factors are:
- Annual flow = (559 x AM flow) + (3596 x inter-peak flow) + (650 x PM flow)
19.2.11 The economic appraisal of options is discussed in Chapter 21 (Economic Performance of Route Corridor Options).
19.3.1 The TMfS:05A is designed to replicate 2005 flows across the modelled area as closely as possible. Consequently, baseline conditions in the model are broadly as per the existing traffic conditions set out in Chapter 3 (Existing Conditions). The accuracy of the model nationwide is addressed in the model calibration and validation reports on the TMfS website.
19.3.2 Two highway only model tests were undertaken to review the sensitivity of the model response to the opening of the M9 Spur Extension in September 2007 and the removal of bridge tolls in February 2008. These sensitivity tests assumed no change in travel demand from the calibrated base model and allow only for change in route choice arising from these interventions. This approach best represents the short term route choice effects of the changes modelled, without the influence of longer term travel behaviour choices, which are represented in the full demand model. This was considered the best approach in the limited time available since these events occurred.
19.3.3 These sensitivity tests indicate that construction of the M9 Spur Extension would contribute to a decrease in traffic using the A90 between Scotstoun and Barnton of around two percent, with a corresponding marginal increase in traffic on the M9 Spur south of the former Humbie Roundabout. These changes are broadly consistent with observed changes in traffic demand in this area.
19.3.4 These sensitivity tests also indicate that removal of the tolls from the Forth Road Bridge would lead to an increase in northbound flows across the Forth Road Bridge, particularly in the morning and evening modelled hours, but little change in southbound flows. The additional northbound traffic forecast to use the bridge is consistent with a modest increase in traffic using the extended M9 Spur in the northbound direction and increased traffic flows on the A90 between Barnton and Scotstoun; to a level similar to that which existed prior to the opening of the M9 Spur Extension.
19.3.5 Taken together, these tests provide confidence that the model adequately represents baseline conditions across the study area and is therefore suitable for the testing and appraisal of the alternative connecting road options considered in this DMRB Stage 2 assessment.
19.4.1 As highlighted earlier, TMfS:05A is a strategic four stage multi-modal forecasting model with a 2005 base year that translates output from the Transport and Economic Land Use Model of Scotland (TELMoS) into forecasts of travel demand on both the road and public transport networks.
19.4.2 TELMoS is a land use model that forecasts future changes in population and employment, based on data from the 2001 census and more recent population forecasts made by the General Register Office for Scotland (GROS), forecast planning allocations provided by the local authorities, and relative travel costs obtained from TMfS:05A, taking account of committed future transport interventions.
19.4.3 TELMoS produces three future year forecasts of population, number of households and employment: 2012, 2017 and 2022. These forecasts are then used within TMfS:05A to generate travel demand forecasts in the years 2012, 2017 and 2022.
19.4.4 Figures 19.1 to 19.4 (Volume 2) show the most significant changes in population and employment forecast by TELMoS (scenario I) in 2017 and 2022 (compared to a base year of 2005). Shaded areas show areas where significant changes are forecast to occur, defined in the context of this Chapter as an increase or decrease of more than 1,500 people or jobs compared with the 2005 base. Darker colours indicate the areas with the most significant changes.
19.4.5 Figure 19.1 indicates the principal areas where TELMoS forecasts a significant change in population between 2005 and 2017. Within the City of Edinburgh, the population is forecast to increase in a number of parts of the city, with forecast growth being strongest in the Leith area. No areas of the city are forecast to see a significant reduction in population. Growth is also forecast in southeast Edinburgh and Midlothian with the forecast growth in population being strongest to the south of Dalkeith in the Newtongrange and Gorebridge area reflecting land release in the ‘A7 / A68 / Waverley Line Corridor’.
19.4.6 Within West Lothian, the population is forecast to grow in several areas, primarily in the M8 Corridor. This growth in population is forecast to be greatest in Bathgate, Livingston and Uphall and Broxburn. It is also significant in Winchburgh, Armadale, Fauldhouse / Whitburn, and to a lesser extent at Pumpherston and East Calder. No areas of West Lothian are forecast to see a significant reduction in population. Grangemouth, within the Falkirk Council area is forecast to see a significant reduction in population, as is the Harthill and Shotts area within North Lanarkshire.
19.4.7 North of the Firth of Forth, significant population growth is forecast in the Halbeath / Duloch Park area of Dunfermline, but a significant reduction in population is forecast in other areas of Fife including central Dunfermline, Dalgety Bay and Aberdour, the Templehall area of Kirkcaldy and the south of Glenrothes.
19.4.8 Figure 19.2 indicates the areas where TELMoS forecasts a significant change in employment between 2005 and 2017. To the south of the Firth of Forth, employment growth is forecast to be strongest in Midlothian and southeast Edinburgh. The growth in jobs is forecast to be greatest at Edmondstone: the area surrounding the Edinburgh Royal Infirmary; and in the Roslin and Bilston area of Midlothian. Both of these locations are designated Economic Clusters of National Importance in the Edinburgh and Lothians Structure Plan 2015 (ELSP). Significant growth is also forecast at other parts of the ‘South East Wedge’, namely around Millerhill and Todhills. This represents the take up of land for proposed development in the ‘A7 / A68 / Waverley Line Corridor’ and ‘A701 Corridor’ Core Development Areas as set out in the ELSP. No significant declines in employment opportunities are forecast in this area, although a slight decrease is forecast in the Penicuik area.
19.4.9 Within Edinburgh, employment opportunities are expected to increase most along the waterfront at Granton and Leith. Growth in employment is also forecast in parts of southwest central Edinburgh, particularly around Haymarket, Fountainbridge, Tollcross and the Meadows. Significant employment growth is also forecast in West Edinburgh at Newbridge, Gogarburn, Edinburgh Park and South Gyle and in the area around Heriot Watt University’s Riccarton Campus. Again, this development is forecast to occur within areas set out as Core Development Areas in the ELSP. No significant declines in employment are forecast within Edinburgh, although there is a slight decrease in employment opportunities forecast in some areas of the city.
19.4.10 Substantial growth in employment is also forecast in West Lothian, particularly in the West Calder area to the southwest of Livingston and in Bathgate. A significant increase in employment opportunities is also forecast in the Blackburn / Boghall, Almondvale, Fauldhouse / Whitburn and Broxburn / Uphall areas. Significant employment growth in the Winchburgh and Hopetoun areas is also forecast. Some of this employment growth is forecast within two of the specified Core Development Areas of the ELSP: ‘Livingston and the Almond Valley’ and ‘Winchburgh, East Broxburn and Uphall’. TELMoS also forecasts growth outside of these Core Development Areas, as highlighted above, in preference to the Armadale Core Development Area. However, some growth in employment is forecast to occur in Armadale, as well as at East Calder and Stoneyburn by 2017. No areas of West Lothian are forecast to see a significant decrease in employment opportunities, although a slight reduction in employment opportunities in central Livingston and the Pumpherston areas is forecast.
19.4.11 Further west, Grangemouth, within the Falkirk Council area, is forecast to see a significant reduction in employment, and an increase in the Larbert and High Bonnybridge area is forecast.
19.4.12 To the north of the Firth of Forth, employment opportunities are forecast to increase in the Kirkcaldy Templehall and Halbeath / Duloch Park areas, indicating a forecast expansion of Dunfermline, principally to the east. This growth is forecast to occur within areas designated for economic development in the Fife Structure Plan 2006-2026. Some reductions in central Dunfermline and to a lesser extent in some other areas are forecast. Significant growth in employment is forecast further north in the area around Kinross.
19.4.13 Traffic is likely to increase most within and between areas where a significant increase in population is forecast and areas where a significant increase in employment is forecast, particularly for movements that are not well served by public transport. Traffic growth will generally be lowest between areas where population and employment opportunities are both forecast to decline. On this basis, traffic growth is likely to be most significant between West Lothian and Midlothian / southeast Edinburgh. Consequently, the underlying demand for travel between West Lothian, Midlothian and southeast Edinburgh is likely to create significant pressures on the connecting road network, in particular the M8, A89 / A8 and A71 routes through rural west Edinburgh and the A720 Edinburgh City Bypass.
19.4.14 Growth in traffic movements within south Fife is likely to be lower as a result of a small decline in population in parts of south Fife and substantially less employment growth than is forecast in West Lothian. However, some growth in cross-Forth traffic would be expected as Fife residents may look to take up employment in growth areas south of the Firth of Forth. As direct public transport links between Fife and West Lothian and between Fife and Midlothian / southeast Edinburgh are limited, much of this demand is likely to translate into road based transport. The growth in traffic across the Forth is likely to be strongest to these new areas of employment, for which the preferred route is likely to be via the M9 Spur or alternative connection towards the M8 at Claylands, with the additional traffic flows splitting at this point between West Lothian and Midlothian / southeast Edinburgh.
19.4.15 Figure 19.3 indicates the principal areas where TELMoS forecasts a significant change in population between 2005 and 2022. The pattern of growth is similar to 2017. Within the City of Edinburgh, TELMoS forecasts further growth in the population in Leith and also continuing growth to the southeast of the city and the expansion of the urban area into Midlothian, with growth forecast to continue at settlements south of Dalkeith. No significant reductions in population are forecast in this area.
19.4.16 Within West Lothian, the population is forecast continue to grow, with growth being strongest in the Winchburgh area. As in 2017, no areas of West Lothian are forecast to see a significant reduction in population. However, the population in the Harthill and Shotts area within North Lanarkshire is forecast to continue to decline beyond 2017.
19.4.17 North of the Firth of Forth, the forecast pattern of population change is little changed between 2017 and 2022, although a significant increase in population is forecast at Forestmill in Clackmannanshire by 2022.
19.4.18 Figure 19.4 indicates the principal areas where TELMoS forecasts a significant increase in employment between 2005 and 2022. The pattern of growth forecast is similar to 2017, but with most of the land allocation in Edinburgh and Midlothian being taken up in full by 2017, growth in employment between 2017 and 2022 is forecast to be strongest in West Lothian. In particular, further growth is forecast in the West Calder area, at Blackburn / Boghall, Almondvale and in the Uphall and Broxburn area. TELMoS also indicates significant growth in the Armadale Core Development Area by 2022, reflecting take up of the majority of zoned land at potentially more desirable locations further east. Within West Lothian, the only area likely to experience a significant reduction in employment opportunities by 2022 is central Livingston.
19.4.19 Within Midlothian and southeast Edinburgh, further growth in employment opportunities is forecast in the Bonnyrigg and Rosewell area of Midlothian and the Greendykes area of southeast Edinburgh. Within the City of Edinburgh itself, there is little additional employment growth forecast between 2017 and 2022, although a significant reduction in employment opportunities is forecast by 2022 in Craigleith and parts of central Edinburgh. Further growth in employment is forecast at Edinburgh Park and at Newbridge on the west of the city. In southern Fife and the Falkirk area, little change in employment is forecast between 2017 and 2022.
19.4.20 The anticipated year of opening for the replacement crossing is 2017 and therefore the design year (15 years after scheme opening) is 2032. The TMfS05a does not forecast this far into the future, primarily due to uncertainty in the location of future development beyond 2022 and the consequent impact of traffic arising from any potential developments. Therefore, it was necessary for design and appraisal purposes to derive potential 2032 traffic matrices and then undertake a highway only assignment using 2022 cost equations and other parameters to create a pseudo 2032 forecast. The derivation of these 2032 matrices is discussed more fully in the following section.
19.5.1 Highway model assignment matrices for 2017 and 2022, were derived from full model runs of TMfS:05A. The full model run reflects changes in the choice of destination, travel mode, trip frequency, and route travelled. However, for comparative purposes between connecting link road options, it is also possible to assign the same fixed pattern of demand to all appraisal options using a highway only assignment. This approach was undertaken for this DMRB Stage 2 comparative assessment.
19.5.2 Consequently, each of the options discussed in Chapter 20 (Effects of Route Corridor Options) was appraised using the same highway matrices in each of the years 2017, 2022 and 2032.
19.5.3 To produce estimates for 2032, traffic forecast to cross the Forth Road Bridge in the 2022 Reference Case was separated from other traffic in the highway assignment matrices so that different traffic growth forecasts could be applied to each.
19.5.4 Bridge traffic was factored by the rate of growth of bridge traffic observed over the most recent 10 years (20%) to estimate growth from 2022 to 2032. The remaining traffic was factored by National Road Traffic Forecasts (NRTF, 1997) central all vehicle growth for the same period (8.4%).
19.5.5 As the rate of traffic growth tends to reduce over time, the use of the full rate of growth over the last 10 years, applied to 2022 forecast levels for bridge traffic is considered to tend towards a ‘worst case’ in terms of both engineering design and environmental appraisal.
19.6.1 The TMfS:05A is intended to assess the impact of large scale strategic interventions by comparing the intervention scenario with a do-minimum or reference case scenario, such that the difference between the two identifies the impacts.
19.6.2 It is therefore necessary to define the committed and most likely changes that will be made to the transport network between 2005 and each of the appraisal years (2012, 2017 and 2022) to obtain the most representative appraisal results. These committed and likely interventions form the TMfS:05A ‘Do-minimum’ and ‘Reference Case’ scenarios respectively and were defined by Transport Scotland in August 2007 and subsequently incorporated into TMfS:05A by MVA.
19.6.3 The ‘Do-minimum’ interventions included within TMfS:05A (source: www.tmfs.org.uk), are listed in Table 19.1.
Table 19.1: Interventions in TMfS:05A Do-minimum scenario
Interventions incorporated in TMfS:05A Do-minimum
2017 & 2022
As 2005 Base Scenario plus:
Cross-Forth rail scenarios:
Scotland’s Railway short-term Infrastructure
19.6.4 In addition to the TMfS:05A do-minimum interventions, a number of non-contentious interventions are considered likely to progress, but are not yet committed. These interventions form the TMfS:05A Reference Case and are listed in Table 19.2.
Table 19.2: Interventions in TMfS:05A Reference Case scenario
Interventions incorporated in TMfS:05A Reference Case
As TMfS:05A Do-minimum plus:
As 2012 Reference Case plus:
Cross-Forth rail scenarios:
As 2017 Reference Case plus:
Cross-Forth rail scenarios:
19.6.5 For appraisal purposes on the proposed replacement bridge, the TMfS:05A Reference Case has been adopted as the do-minimum case for environmental appraisal and is therefore referred to as the Environmental Do-minimum.
19.6.6 The TMfS:05A Reference Case assumes that the Forth Road Bridge will remain open in 2012, 2017 and 2022 with the existing capacity maintained. The structural information currently available from the Forth Estuary Transport Authority (FETA) suggests that this is unlikely, and that complete or partial closure to traffic (or certain classes of traffic) may be required, either temporarily while repair work is undertaken, or permanently. Consequently, the previous Forth Replacement Crossing Study undertaken as part of the Strategic Transport Projects Review assumed a do-minimum scenario with no bridge in place; that is assuming that the Forth Road Bridge closes to all traffic in 2017. This would result in a substantial reduction in cross-Forth trips as work and leisure trip patterns would change. The remaining cross-Forth traffic would generally re-route via Kincardine or Stirling. This is referred to as a ‘No Bridge’ scenario in this assessment, which is as per the TMfS:05A Reference Case but with the Forth Road Bridge closed.
19.7.1 Figure 19.5 indicates Annual Average Daily Traffic (AADT) flows on the wider road network in 2005, while Figure 19.6 indicates forecast AADT flows over the same area in 2017 representing the two potential minimum intervention scenarios referred to in Section 19.6. The first of these is the TMfS:05A Reference Case or Environmental Do-minimum scenario, which assumes that the Forth Road Bridge remains open to traffic. The second set of forecasts assumes a ‘No Bridge’ scenario, which is the do-minimum for economic appraisal. The ‘No Bridge’ scenario assumes closure of the Forth Road Bridge with no replacement crossing constructed, but is otherwise the same as the Environmental do-minimum. Under this scenario, cross-Forth traffic must use one of the bridges at Kincardine or in the Stirling area.
‘No Bridge’ Scenario
19.7.2 The impact of a scenario where the Forth Road Bridge were to close in 2017 with no replacement crossing provided in the Queensferry area, would have a substantial impact on traffic flows across a wide area of east central Scotland. To the north of the Firth of Forth, traffic flows would decline most significantly on the M90 / A90 to well below existing levels of traffic. The strategic nature of the corridor means that a significant proportion of the traffic flow would divert towards Stirling or Kincardine from a significant distance north of the Firth of Forth, generally at Perth, following the A9 towards Dunblane, or at Kinross, following the A91 westwards.
19.7.3 Traffic would also drop on the A92 East Fife Regional Road, although the forecast decline in traffic would only be to current levels, with the lesser decline reflecting the reduced route choice for travel to and from the areas of Fife served by this road. A marginal decline in traffic on the A921 coast road would also be expected, although as this route mainly carries local traffic, the impact would be significantly less than the declines forecast on the trunk road network.
19.7.4 To the west of Dunfermline, traffic would be anticipated to double on the main routes towards Kincardine: the A985 trunk road and the A994 through Crossford as a result of the bridge closure. Traffic would also be expected to double on the A977 north of Gartarry Roundabout, principally as result of traffic diverting from the M90 at Kinross via the A91. Taken together, these flows would result in a significant increase in traffic on both the existing Kincardine Bridge and the Upper Forth Crossing, currently under construction to the west of Kincardine. The forecast increase in traffic would be greatest on the existing Kincardine Bridge because it is best placed to serve the demand to and from Dunfermline and the south Fife coast. The Upper Forth Crossing is better placed to cater for longer distance traffic from the north or northeast of Scotland travelling via the A91 and A977. Forecast traffic flows on the existing Kincardine Bridge under a ‘No Bridge’ scenario would be more than 50 per cent above existing levels and therefore significant delays would be likely.
19.7.5 To the south of the Firth of Forth, the additional cross-Forth traffic around Kincardine would result in a significant increase in traffic flows on the M9 (particularly to the east of Junction 7). Forecast traffic levels would be more than twice existing flows between Junction 7 and Junction 1a. A small increase in traffic using north south routes from the M9, such as the A801 and B8046 would be expected, but most of the additional traffic would remain on the M9 as far as Junction 1a.
19.7.6 Within the southern bridgehead area, flows on the A904 through Newton village would be expected to increase to more than twice existing levels. Flows on the A90 east of Echline would be expected to drop by up to fifty per cent. Traffic on the M9 Spur would be expected to drop significantly, as this would become little more than a local access route to South Queensferry This also contributes to a reduction in traffic on the M9 between Junction 1a and Newbridge. Forecast traffic flows on the A8 between Newbridge and Gogar and the M8 between Claylands and Hermiston Gait would be broadly similar with and without a crossing at Queensferry.
19.7.7 The adverse impact on traffic flows across east central Scotland, particularly in the vicinity of Kincardine and Falkirk, is substantial enough to imply that closure of the Forth Road Bridge, with no infrastructure improvements on the many diversionary routes, is not a desirable option. Prolonged closure of the Forth Road Bridge, for any reason, would likely necessitate either substantial capacity enhancements on these diversionary routes, or a replacement crossing close to the site of the existing bridge. The findings of the Forth Replacement Crossing Study undertaken as part of the Strategic Transport Projects Review justified the need for a proposed replacement bridge on this basis.
19.8.1 The Transport Model for Scotland (TMfS:05A) has been used to provide existing and future forecast traffic flows. Details of the model development, operation, calibration and validation of the model are set out in reports available on the TMfS website (www.tmfs.org.uk). The model validates well against observed data on the Forth Road Bridge and responded as expected to sensitivity tests undertaken to identify the effects of the opening of the M9 Spur Extension in September 2007 and the removal of bridge tolls from the Forth Road Bridge in February 2008.
19.8.2 Future changes in land use, population and employment are forecast using the Transport Economic Land-use Model of Scotland (TELMoS) for the period until 2022. This is then used within the Transport Model for Scotland (TMfS:05A) to create travel demand forecasts for 2017 (the opening year of the proposed replacement bridge) and 2022. Traffic forecasts for the design year (2032) for engineering design purposes and environmental appraisal have been derived by factoring the 2022 forecast matrices using a combination of historic growth for cross-Forth trips, and National Road Traffic Forecasts (NRTF) Central Growth for other traffic. These revised matrices were used to create 2032 forecasts.
19.8.3 Do-minimum and reference case infrastructure was defined by Transport Scotland in August 2007 and incorporated in TMfS:05A by MVA. For the purposes of DMRB Stage 2 assessment, the TMfS:05A Reference Case has been taken as the do-minimum for Environmental Appraisal, while a ‘No Bridge’ scenario has been taken as the proposed replacement bridge do-minimum for economic elements of scheme appraisal.
The City of Edinburgh Council, East Lothian Council, Midlothian Council, West Lothian Council. Edinburgh and Lothians Structure Plan 2015 Fife Council. Fife Structure Plan 2006 – 2026