Salisbury junction improvements

The engagement survey has now closed, but there will be further opportunities to have your say.

Yes. Further consultations will be undertaken when the proposals have been designed in more detail and we have a better idea of the construction programme.

Any traffic regulations required in connection with the scheme will be the subject of separate formal consultations.

The A36 is a trunk road managed by Highways England and forms part of the strategic road network. This route is the subject of a separate strategic study which is being undertaken on north-south routes by Highways England.

The Exeter Street Roundabout, Harnham Gyratory and Park Wall junctions are on the A338, A3094 and A36. The A338 and A3094 are part of the Major Road Network (MRN), although Park Wall junction on the A36 is part of Highways England's network. The MRN is a middle tier of the country's busiest and most economically important local authority 'A' roads. Wiltshire Council is responsible for these local roads and is promoting these improvements as local priorities as there is separate funding available to improve them.

The A338 and A3094 south of Salisbury form part of the nationally designated Major Road Network (MRN), which is a middle tier of the country's busiest and most economically important local authority 'A' roads.

The Salisbury Transport Study identified key junctions in the study area where improvements would be required to address existing problems and accommodate future traffic flows.

There are delays and congestion at the three junctions, which are affecting both longer distance traffic on the MRN and traffic using the junctions for local journeys. From the initial assessment work there appears to be a good economic case for carrying out improvements.

The scheme was one of nine priority schemes identified by the Western Gateway Sub-national Transport Body, for more information visit Western Gateway Sub-National Transport Body (opens new window).

In March 2020, the Government awarded funding to further develop the case for the junction improvements, having considered our initial submission made in July 2019.

We are now undertaking technical exercises to enhance the evidence base for improvements, and this work will inform an updated business case to be submitted to the government shortly.

The scheme is being promoted through the Department for Transport's funding for improving the Major Road Network.

Traffic problems in and around Salisbury have been of concern for many years. The following key transport problems have been identified:

• The strategic role of the A338 and A3094 (MRN) will be threatened by increased congestion and delays.
• Increased traffic volumes, congestion, delays, accidents and severance will make Salisbury an unattractive place to live, work and visit.
• Active and sustainable travel modes are discouraged in favour of car travel with potential impacts on health.
• Congestion related shunts occur frequently at Harnham gyratory and Exeter Street roundabout

The delays, congestion, and uncertainty of journey times has a cost in economic and environmental terms. These affect businesses, buses, visitors, shoppers and local residents. The problems can deter visitors and tourists and reduce the attractiveness of the city, with consequential economic impacts.

The delays on the major road network are particularly significant because of the importance of these routes to the national and local economy. The adverse effect on air quality, severance and the carbon implications of the existing situation are also factors.  

There are safety concerns at the junctions especially for pedestrians and cyclists.

The Outline Business Case will be submitted to the Department of Transport shortly.

If it is approved it is anticipated that funding will be made available for the detailed design of the scheme, and for obtaining prices from contractors.

Once the detailed design is completed and the costs and benefits have been confirmed the scheme construction will start, which could be in autumn/winter 2023.

An Outline Business Case (OBC) captures the findings of the overall assessment and option selection process. This is a document that will set out the justification of the scheme, presenting its cost to deliver and the benefits it will deliver to the community and the local and national economies. The OBC is broadly divided across five chapters, each capturing the assessment work as part of a distinct topic paper or chapter: 

• Strategic Case 
• Financial Case 
• Economic Case 
• Management Case 
• Commercial Case 

The Outline Business Case will be submitted to the Department for Transport (DfT) with supporting information as an application for scheme approval. DfT will then assess the scope and content of each of the OBC chapters to ensure they have been considered in sufficient detail to be compliant with DfT's reporting requirements. This assessment will include DfT reviewing the Transport models and the detail of the supporting evidence.

The OBC will also be reviewed against the feedback received from the public consultation exercise to ensure the views of the local community have been properly considered and that the case put forward for the scheme stands up to scrutiny. 

If DfT is satisfied that the design of the preferred route option is sufficiently robust and the assessment work has been carried out to an acceptable standard, then it will grant approval for government funding for the next stage of the scheme, which is formal design of the road and the invitation of tenders from contractors. 

The Strategic Outline Business Case (SOBC) established the strategic need for the scheme. The proposals are now being developed in more detail to identify a preferred option. The information in the SOBC will be updated in the Outline Business Case (OBC) currently being developed.

The aims of the scheme for the Major Road Network identified in the Strategic Outline Business Case (SOBC) are to: 

• Reduce instances of queuing on the MRN within Salisbury.
• Minimise delays at the Harnham gyratory, Exeter Street roundabout and Park Wall junction.
• Reduce collisions and accidents at Harnham gyratory and Exeter Street roundabout.
• Improve the capacity of the scheme junctions to deal with congestion impacts of future development.

The related local transport aims are to:

• Provide enhanced opportunities for walking and cycling between the city centre and the residential areas in Harnham, Wilton and Salisbury District Hospital, and
• Reduce delays for all road users, including buses.

There is the potential to deliver many strategic and local benefits including:
 

• Creating a more reliable, less congested, and better-connected transport network that works for the users who rely on it. 
• Providing a well-connected, reliable and resilient transport system to support economic and planned development growth at key locations. 
• Supporting and helping to improve the vitality, viability and resilience of Wiltshire's economy and the city. 
• Providing transport infrastructure to support new housing in the area.  
• Assisting the efficient and sustainable distribution of freight in Wiltshire to build stronger, more balanced economy by enhancing productivity and responding to local growth priorities. 
• Supporting and promoting a choice of sustainable transport alternatives. 
• Reducing the level of air pollutant and climate change emissions from transport. 
• Improving safety for all road users and reducing the number of casualties on Wiltshire's roads. 
• Improving walking and cycling routes from the city to the south and Salisbury District Hospital. 
• Improving walking and cycling routes from Wilton to the city. 

Various options were considered in the Strategic Outline Business Case (SOBC) such as demand management through road user charging, increased parking charges, public transport improvements, improved walking and cycling movements, but these in themselves would not meet the aims in connection with the Major Road Network and the strategic requirements.

Larger scale options such as widening Harnham Bridge, or road widening at Exeter Street have also been considered, but the cost and environmental impacts would be significant, and these are not considered to be feasible.

The initial assessment work concluded that junction redesign at Exeter Street Roundabout and Harnham Gyratory, with signal design optimisation at Park Wall Junction would best meet the requirements in terms of cost, efficiency and environmental impact.

The introduction of a signal-controlled T junction and other arrangements at Exeter Street junction were investigated, but assessment against future traffic flows indicated that they would have less capacity than an enlarged signal-controlled roundabout.

At Harnham Gyratory a staggered T junction layout was investigated, but there was insufficient width to accommodate the traffic lanes required for turning movements, and there was a need to accommodate U-turn movements at the junctions because of restricted turn movements elsewhere.

Park Wall junction is very constrained because of the wall, railway and properties and major changes to the road layout were not considered feasible at that location.

All three junctions have limited space available and are very restricted, either by physical features, historic boundary walls, environmentally sensitive areas or residential properties. There is insufficient room to accommodate such structures without having serious adverse environmental impacts and they would be very expensive.

The proposals have been assessed in accordance with the Department of Transport's methodology which compares the costs with the value of the benefits, especially in terms of reduced vehicle operating costs and accidents. The current proposals are considered to be the best options for attracting investment.

Other larger scale improvements would be more expensive, very environmentally damaging and would not offer value for money.

Not improving the junctions would result in increased delays and congestion at the junctions, with consequent costs in terms of journey times and vehicle operating costs.

Yes. Any comments will be considered for potential inclusion as the scheme develops.

If approved, and depending on the final details, the scheme could cost in the region of £15 million. 

Wiltshire Council would not be able to fund a scheme of this type from its own resources. It would be necessary to bid for funding from the Department of Transport (DfT) and to make the case for the scheme by preparing a business case which would include the cost and economic benefits. The decision regarding funding for the scheme would be made by the DfT after considering the business case. 

There is no set budget for the scheme. However, the initial assessment work indicates that the current proposals costing in the region of £15 million would be viable and would be good value for money when assessed using the Department for Transport methodology. 

The estimated scheme costs will be refined as the proposals are developed in more detail. At this early stage, a risk allowance is included in the estimated scheme cost to provide a contingency item and to allow for unknown costs.

As the scheme design progresses the costs become better defined and the risk element reduces. The viability of the scheme will be reassessed before construction starts. At the construction stage any cost overruns are likely to have to be met by the Council, which is why care is taken to ensure the cost estimate is as accurate as possible prior to construction starting.   

Funding contributions from approved developments may be possible. Any future planning applications by others will be considered on their merits in accordance with the regulations and relevant guidance and policy.

A revised Local Plan is scheduled to be adopted before commencement of works on site to deliver the scheme. Through development of the Local Plan, a transport evidence base will be produced, and this will propose mitigation measures to support housing development being brought forward. Should the evidence base provide a direct linkage between housing delivery and the need for road improvement schemes, such as at the junctions, then Local Plan policy may reflect this and provide material support for the collection of contributions towards the cost of the scheme.

As well as the public, the city, town and parish councils, Area Board, local businesses, walking and cycling groups and other relevant organisations will be invited to comment on the scheme and the options. This will include the Environment Agency, Natural England, Highways Agency, and other organisations with specialist knowledge. 

Generally, highway authorities are permitted to carry out improvements of this type without requiring planning permission, but this may depend on the final scheme details.

It is not expected that a public inquiry will be required for schemes of this type.

Some traffic regulation orders, and other legal processes may need to be followed, especially in connection with installing traffic signals, any changes to speed limits or other traffic management measures connected to the scheme.

During construction temporary traffic regulations may be required for safety reasons, including temporary speed limits.

The responses will be analysed and summarised in a report which will be publicly available. The information collected will help to inform the development of the Outline Business Case and the details of the scheme. 

New purpose-built roads and associated infrastructure generally do not have the maintenance problems associated with older roads that have evolved over the years and were never envisaged to carry the volumes and types of traffic now using them. Maintenance costs are taken into account in assessing the scheme but are not usually a major consideration compared to the other factors. 

The scheme costs are estimated using a price base, which can then be adjusted according to the latest predictions of inflation for future years, when the expenditure is likely to be incurred.

The scheme benefits are likely to arise over a significant number of years in the future, and these are discounted back to a base year in order to derive a cost benefit ratio for the scheme. The factors and allowances for inflation are updated by the Department for Transport from time to time as additional information becomes available. 

The scheme will be assessed in accordance with the Department for Transport's Transport Analysis Guidance (TAG). Further information is available at GOV.UK: Guidance Transport analysis guidance (TAG) (opens new window).

This methodology and guidance are the standard approach to assessing major transport schemes of this type, and the information is regularly updated by DfT.

The requirements for the scheme will be considered when it has been designed in more detail. The environmental factors will be described and assessed in the Outline Business Case. 

The impact of the scheme will be considered in the light of emerging policies and strategies at Government and local level. The reduced traffic congestion, better facilities for active travel, and improved road safety would be expected to reduce energy consumption as a result of the scheme.

There will be scope for the use of energy efficient plant, materials and processes to reduce the carbon footprint of the construction stage of the scheme, and traffic signals will be extra low voltage and LED to minimise ongoing carbon output.

Consideration of carbon reduction requirements will be reviewed as guidance is updated.

The potential effects of climate change will be considered in the design of the scheme. This would include making allowances for increased rainfall and flood risk, as well as the use of more durable materials to provide resilience in connection with increased temperatures and other impacts of climate change. 

The junction improvements will provide significant opportunities for providing enhanced walking and cycling facilities between the city centre and residential areas.

These are being designed into the proposals and consulted on at the earliest stage to ensure suitable provision is made to encourage alternatives to the use of the car. 

No. The number of traffic lanes are not being reduced to accommodate cycling. The cycle tracks at the junctions will be provided off the carriageways for safety reasons.

The walking and cycling phases at the traffic signals will generally be integrated into the vehicle movement phases.

The junction improvements will reduce delays for all traffic between the city centre and residential areas, including buses.

Consideration has been given to the provision of separate bus lanes but there is not sufficient road space available to provide them without serious adverse effects on capacity at the junctions.

The business case for the scheme will need to consider a range of traffic growth scenarios for both high and low growth. It is anticipated that the Government will revise future traffic and economic growth figures in view of recent events, and the scheme will be assessed based on any revised Government predictions as they are published. 

The scheme has the potential to improve road safety and reduce the number killed and seriously injured on our roads. The removal traffic delays could reduce traffic noise and air pollution with consequent health benefits for residents and road users. The Outline Business Case for the scheme will take these factors into consideration. 

A Wiltshire Traffic Model has been created which covers the wide area of the county. This computer model makes use of a large number of traffic counts across the highway network. It is not just based on traffic counts in the Salisbury area. This allows schemes and proposals across the county to be modelled with a high degree of accuracy, and enables the computer modelling of combinations of road and development proposals to be assessed. Having robust data to inform options appraisal is an important part of the scheme assessment process.

The improvements will reduce delays at Exeter Street Roundabout and Harnham Gyratory, especially during the morning peak period. The table below illustrates the average time savings for example journeys northbound through Harnham Gyratory and Exeter Street Roundabout during the morning peak for the 2036 scenario, which is the worst case scenario in terms of traffic volumes. It should be noted that these are initial results and further model refinement will be undertaken as the scheme progresses.

At Park Wall Junction the signals will be updated to ensure that they work with current traffic patterns, reducing queues and delays dynamically as traffic levels vary throughout the day.

The introduction of signals has been modelled to assess the impact at both Exeter Street Roundabout and nearby Harnham Gyratory. The traffic signals will reduce delays significantly in the morning peak when traffic flows are high by controlling the circulating traffic and easing the entry onto the roundabout. During the day the traffic modelling indicates that there will be a negligible effect on average journey times.

The scheme is being prepared in accordance with Department for Transport (DfT) guidance, and the traffic model is validated and checked by using separate traffic counts. The traffic modelling will be reviewed by DfT during the development of the scheme to ensure that the modelling and economic assessments are robust. The business case for the scheme will be assessed by experts at the DfT before funding for the scheme is awarded. 

The emerging Local Plan is expected to result in proposals for additional housing in the county in order to meet Government targets. The nature and location of this will be determined by the Local Plan process, which will use a similar traffic model to the scheme to ensure consistency. The traffic modelling for the scheme will be rerun and reviewed as further information on growth and future traffic movements becomes available. 

Induced traffic can occur when there is a suppressed travel demand, especially because of severe congestion on a network. This can result in an additional increase in traffic. The traffic modelling being carried out will consider this aspect, including taking into account other factors influencing traffic growth on the network as a result of population and employment growth.

Any changes to traffic management in the city centre may affect traffic flows on the routes into and around the city. The potential effect of these on the junctions would be modelled as measures are developed or changes made. 

The street lighting at the junctions will be reviewed and altered to ensure it meets current standards, especially with regard to reducing light spill and improving energy efficiency. 

Landscaping and planting would be included in the scheme where it would help to reduce the visual impact. The exact arrangements would be determined as part of the detailed design, taking into account the local environment and setting. 

The assessment of the scheme in connection with the Outline Business Case will consider the environmental aspects of the proposed scheme and any potential mitigation measures. The current consultations and information being collected will help inform the design of the proposals to reduce the impact of the scheme. 

Yes. Information on the area is being used to inform the design and as the scheme develops more specialist investigations and surveys may need to be carried out. Specialist advice will be sought in order to identify appropriate measures required in connection with the scheme.

Exeter Street Roundabout is located in Salisbury's Air Quality Management Area where the annual average of nitrogen dioxide exceeds specified limits. Therefore, there are clearly air quality issues in connection with the existing road. The effects on traffic flows and air quality as a result of the scheme will be considered and will form part of the assessment in the Outline Business Case. 

The scheme assessment process will include consideration of traffic noise and the potential changes with the scheme. 

The drainage systems will need to be designed so as not to increase flood risk and would include an allowance for predicted climate change. As well as flood risk it will be necessary to consider water quality as well. 

Generally, the junction improvements will be made within the existing highway boundaries, although discussions will be held with the city council about some land at Harnham Gyratory for the junction and on New Bridge Road for a wider cycle lane. 

It is currently anticipated that construction would start in autumn/winter 2023, with the scheme opening in autumn/winter 2024. However, this would depend on approval of the Outline Business Case.

Yes. the Outline Business Case which is currently being developed, and the supporting documentation will be available to the public.