Agenda item

Jonathan Hill delivered a presentation and answered the members’ questions with Alan Feist, Cabinet Member Catrin Maby and Deb Hill-Howells: 

 

• What consideration has been given to the impact on Magor Roundabout (Junction 23A), as it was not covered in the presentation but is a key part of the traffic network? 

 

Magor Roundabout is not part of the National Highways network, as responsibility ends at the eastern extent of the bridge. However, its importance is recognised and National Highways funded the signalisation of the roundabout to help mitigate impacts. Ongoing engagement is taking place with Welsh Government, Monmouthshire County Council and other partners, and councillors will be kept informed through those channels. 

 

• Where will HGVs be stacked under the proposed system, and will this create congestion around junctions or local areas? 

 

There is no expectation of significant stacking under the proposed system. The design means traffic signals will remain green most of the time, allowing HGVs to move continuously. Any queuing will be minimal, typically only two or three vehicles on slip roads, and large-scale holding of vehicles is not anticipated as the system is designed to manage incidents rather than routine traffic flow. 

 

• What happens when the bridge is closed – will the system still prevent congestion and stacking? 

 

In the event of a bridge closure, there will still be significant congestion, similar to current situations. The proposed system is not designed to manage the wider network impacts of closures but is intended to allow HGVs to use the bridge safely when it is open and to reduce the economic impact of the weight restrictions. 

 

• How is the wider network, particularly Magor Roundabout, being considered within the overall solution given its direct connection to Junctions 1 and 2? 

 

National Highways is aware of the interdependence between their network and surrounding routes, including Magor Roundabout. Regular communication takes place with Welsh Government and other stakeholders through operational discussions and a stakeholder steering group. While responsibility for the roundabout lies elsewhere, National Highways is actively engaged and will continue to share information to support coordinated decision-making. 

 

• Given the recent breaches of the weight limit at the Menai Bridge, are you liaising with the authority responsible, and are there any lessons you can learn from their experience when implementing your own technology? 

 

National Highways confirmed that they are aware of the issues at the Menai Bridge. They advised that the technology being used there differs from the one proposed for the Severn Bridge, but they will remain in contact and continue engagement through the stakeholder steering group to ensure that any relevant lessons are identified and taken into account. 

 

• What are the costs to date for this project, what is the estimated cost of the medium-term solution, and who is funding it? 

 

The costs incurred to date for the medium-term solution are approximately £1.5 million, covering feasibility work, detailed design and early procurement activity. The current estimated total cost for the medium-term solution is in the region of £23 million. This is being funded by National Highways through grant funding from the UK Government, with no specific funding currently allocated from Welsh Government, although they are supporting the legislative processes required on their side. 

 

• When you say the scheme represents value for money, can you explain what that means in practical terms? 

 

The value for money assessment is based on the economic benefits to traffic, particularly HGV movements, from being able to use the bridge instead of diverting. In broad terms, the analysis shows that the economic savings generated are greater than the cost of the scheme when assessed over a period of more than seven years. If the scheme operates for less than seven years, the value for money is less strong, but it is expected to be needed for longer than that. 

 

• What are the likely costs of the long-term solution, and are previous estimates of £300 million to £600 million still accurate? 

 

There is no updated estimate at present, as further feasibility work is ongoing. However, previous estimates for long-term remediation, such as cable augmentation, have been in the range of £300 million to £600 million. The current studies will refine these figures once technical options are further developed. 

 

• Who is expected to fund the long-term solution, particularly if costs are in the hundreds of millions? 

 

It is expected that funding would come through National Highways, which in turn is funded by the UK Government (Westminster). 

 

• What work is being done to assess the wider and immediate economic impacts, such as increased transport costs, congestion, tourism impacts, and pressures on alternative routes? 

 

There are effectively two business case processes. For the medium-term solution, a formal business case has already been developed and approved internally to secure funding, focusing primarily on economic benefits to traffic. For the long-term solution, an outline business case is currently being developed as part of the feasibility work and will follow Treasury Green Book methodology. This will include assessment of transport impacts, socioeconomic effects, land use and wider economic considerations. However, the detailed analysis of these broader impacts is part of the longer-term business case work and has not yet been completed. 

 

• Committee members would like to request sight of the business case for the medium-term solution and also the preliminary and full business cases for the longer-term solution.   

 

National Highways will need to check internally with their planning, economics and governance teams before confirming whether the business case documents can be shared, as there may be restrictions on their release.  

 

• Can Welsh Government be invited to attend the committee to provide an update on Junction 23A and its management? 

 

The Chair agreed with this request. 

 

• Why were local elected members not informed in advance about the installation of traffic signals at Magor Roundabout, and why was there no clear communication about how they would operate? 

 

National Highways acknowledged that, while there had been general reference to signalisation in earlier communications, there had not been sufficient communication about the timing and implementation. They accepted that communication could have been better and acknowledged this as a shortcoming. 

 

• Why are the signals at Junction 23A operating continuously, and why has there been limited movement analysis and slow progress in reviewing their impact? 

 

National Highways indicated that management of the junction sits with Welsh Government, but confirmed they would take away the concern about communication and the need for clearer information on timescales and management. 

 

• How can effective decisions be made when not all relevant stakeholders are present, given that issues extend beyond the National Highways network? 

 

National Highways acknowledged that they are only one stakeholder and are somewhat removed from certain aspects of the wider network. They reiterated that they are working closely with Welsh Government and other partners and recognised the importance of ensuring clearer communication and coordination across all parties. 

 

• What is the timeline for the crash barrier works at Junction 2, given the current 50mph restriction, and could this affect the implementation of the bridge plans if it continues beyond October? 

 

National Highways advised that the crash barrier works fall under the responsibility of Welsh Government and Sustrans rather than their own network. While they could not provide specific timescales, they confirmed that the work is being coordinated between National Highways and those organisations as part of wider planning activity, and that further detail would need to come from Welsh Government. 

 

Councillor Maby, Cabinet Member: 

 

Councillor Maby clarified that the issues raised – such as crash barriers, Junction 23A, and wider traffic management – are primarily matters for Welsh Government and Sustrans. She stated that the Council is actively seeking answers from Welsh Government, as they do not have direct control over those aspects. She also highlighted that MCC Highways is represented at Director level (via Debra Hill-Howells), ensuring the Council is engaged in discussions even if it cannot provide definitive answers itself.  She supported Councillor Taylor’s concern that key stakeholders (particularly Welsh Government) were not present and therefore unable to answer questions fully. She stated that it reinforced the point that National Highways and the Council cannot account for all issues, as responsibility is split across multiple organisations, particularly in relation to Councillor Rooke’s question regarding crash barrier timelines by confirming that responsibility lies elsewhere. 

 

Response - Deb Hill-Howells: 

 

Deb acknowledged the growing frustration among members, particularly regarding the lack of clear responses on Junction 23A. She confirmed that she has been actively engaging with Welsh Government to obtain answers and is working to improve communication. She suggested arranging a tripartite meeting between National Highways, MCC, and Welsh Government could improve coordination and information sharing (Action~ Deb HH).  She also explicitly stated that: It is appropriate that Welsh Government attend scrutiny to answer questions directly. The situation involves multiple agencies, and communication between them and with the public needs to improve. 

 

• Under the proposed system, how many HGVs or what level of demand would trigger the traffic signals, and how is that controlled? 

 

The system is designed to ensure that no more than approximately 10 HGVs are on the bridge at any one time. It uses a combination of weigh-in-motion sensors, ANPR cameras and real-time monitoring to track vehicles entering and leaving the bridge. The signals operate dynamically, with a response time of around 0.2 seconds, and will only turn red briefly if needed to maintain this limit, for example if a large group of vehicles arrives together. 

 

• How many HGVs could queue on the slip roads under the new system, and is there a risk of queues extending back onto the motorway or junction? 

 

The number of HGVs that could queue depends on the time of day and overall traffic conditions, as HGVs will be mixed with general traffic. Modelling suggests that typically around four or five HGVs could be accommodated on the slip roads before reaching the junction. However, this level of queuing is not expected to occur under normal conditions. The main risk of queuing arises during the morning peak, which is why an HGV restriction during that period is being proposed. 

 

• Is there an ongoing assessment of whether the M4 Prince of Wales Bridge has sufficient capacity to accommodate diverted HGV traffic? 

 

National Highways confirmed that they are satisfied that the Prince of Wales Bridge has sufficient capacity to handle HGV diversions. However, they noted that if additional traffic, such as private vehicles, were also diverted, it would not have sufficient capacity, which is why congestion occurs when the M48 bridge is closed. 

 

• What progress has been made on the M49 junction at Severnside, and will its opening reduce pressure on the M48 corridor? 

 

It was confirmed that the opening of the M49 junction would help reduce pressure on the M48, as it would allow traffic to access Avonmouth directly without needing to cross the bridge and return via Junction 1. This would reduce unnecessary movements on the M48. The link road associated with the junction is expected to open in spring next year. 

 

• When will the interactive traffic modelling tool be available, so that members can better understand how the system will work in practice? 

 

National Highways confirmed that they expect to have the interactive model available in July. They indicated that this will allow members to see how different vehicle movements operate at various junctions and times of day, and that it can be presented to the committee to help explain the system visually. 

 

• Can you explain, in simple terms, how the proposed system will work for both cars and HGVs travelling from the Chepstow area onto the motorway? 

 

It was explained that, under normal conditions, both cars and HGVs travelling from the local road network onto the M48 would generally experience a green signal and be able to proceed onto the motorway without delay. However, during the morning peak, HGVs may be required to divert via the M4 and Prince of Wales Bridge, while cars would continue to use the M48 as normal. Outside the peak period, both vehicle types would largely proceed without restriction, as traffic volumes are lower. 

 

• Can you explain how the system will work for vehicles, particularly cars and HGVs, exiting the motorway towards Chepstow? 

 

National Highways stated that car traffic exiting towards Chepstow would continue largely as it does now, using the existing slip roads and roundabouts without additional controls. HGVs, however, would be required to leave and rejoin the motorway at controlled points (such as Junction 1) where signals regulate their entry onto the bridge, although in most cases these signals would remain green. 

 

• How will the impact of the scheme on local traffic, particularly congestion in the Chepstow area, be monitored? 

 

It was confirmed that the system will include live monitoring capabilities, primarily focused on HGV movements, using technology such as ANPR and traffic sensors. In addition, post-implementation reviews will be carried out, particularly during the initial trial period of approximately three to six months. During this time, traffic conditions, including queue lengths and impacts on general traffic, will be monitored and adjustments can be made to the operation of the system to minimise negative impacts. 

 

• Are you proposing that additional HGV traffic will be diverted onto the M48 towards Magor Roundabout during the morning peak, potentially worsening existing congestion? 

 

No additional HGV traffic is being introduced compared to the current situation. During the morning peak (approximately 06:00–10:00), the existing arrangement will remain in place, meaning HGVs are already required to divert via the M4 and Prince of Wales Bridge. The new system simply maintains this current restriction during those hours, rather than adding further traffic to that route. 

 

• Can you confirm that your modelling work has used the most up-to-date traffic data, including information held by Sustrans/Welsh Government on High Beech roundabout and the wider network? 

 

National Highways indicated that, to the best of their understanding, their modelling is based on a combination of traffic models and updated data. This includes traffic counts taken before and after the weight restriction was introduced, as well as data received from Sustrans/Welsh Government.  

 

• Are there broader lessons being learned from other bridge schemes across the country, and are experiences and technologies being shared so that different areas are not dealing with the same issues in isolation? 

 

National Highways advised that while there are other bridges facing similar challenges, this scheme is effectively one of the first of its kind. As a result, they are in a position of developing the approach ahead of others and will generate learning that can be applied elsewhere, rather than drawing extensively on established solutions from other locations. 

 

• Will National Highways be able to return in July to present the interactive model, so members can see how the system works in practice? 

 

National Highways confirmed that they would be willing to present the interactive model in July. They advised that they plan to hold user acceptance testing sessions during that period, including workshops with both the HGV industry and political representatives, and would be happy to present the model either to the Scrutiny Committee or to a wider group of members as part of those sessions (Action: to arrange a workshop and invite all members). 

 

• What should the public expect from this proposal, and what are the realistic longer-term options for the bridge (e.g. alternatives such as major reconstruction or new infrastructure)? 

 

National Highways advised that the medium-term solution will not resolve all existing traffic issues but is intended to provide a better balance for all users by allowing HGVs back onto the bridge in a controlled way. In terms of long-term options, they confirmed that a full evaluation process will be undertaken before any decisions are made, so no specific alternative solutions can be confirmed at this stage. However, early indications suggest that the most likely approach is cable augmentation (adding additional cables to strengthen the existing bridge), although this would be costly and require careful consideration by government. 

 

• Do you have a ‘plan B’, such as a new bridge or alternative solution, if the current approach does not work? 

 

National Highways did not set out a specific alternative proposal. They referred back to their earlier response, stating that any long-term solution, including options such as a new bridge, would need to go through their formal evaluation process. As such, they cannot comment on specific alternatives at this stage until that process has been completed.  

 

Chair’s Summary: 

 

The Chair thanked the guests and confirmed that a workshop would be arranged in the autumn to examine the modelling. He also advised that Welsh Government and SWTRA would be invited to a future meeting to discuss areas highlighted in the meeting that fall under their responsibility.  

 

The Chair suggested a separate meeting outside of the formal scrutiny process be arranged with National Highways, with relevant members in South Gloucestershire invited so that both sides of the border could be involved in the discussion.  There was a suggestion to invite the Transport Ministers and National Highways indicated they would be happy to assist in setting that up.  

 

The Chair reminded the committee that a response had not been received from National Highways in relation to the Committee’s recommendation that there is democratic elected membership o the Steering Group and he confirmed that he would be writing to the new Chief Executive to request a response. (Action: Scrutiny Team to draft a letter to the CEO National Highways.