Improvements to junction 28 on the M4 achieved CEEQUAL Excellent

The M4 Junction 28 roundabout and adjacent roundabouts at Bassaleg and Pont Ebbw are used by more than 6,000 vehicles an hour at peak times. Strategically, M4 Junction 28 is the principal link between the M4 and west Newport, which is a major employment area. It also provides a north-south link between the eastern South Wales valleys and west Newport.

The improvement of all three junctions is seen by the Welsh Government as an important part of its programme for economic regeneration providing access to jobs, safe reliable journeys and improved resilience for the trunk road and local network in south east Wales. It will also reduce emissions and improve air quality by reducing congestion.

The construction programme commenced in February 2017 in a phased approach and took 16 months to complete.

The scheme specific objectives were to:

• Increase throughput at the junctions

• Increase to use of the Southern Distributor Road (SDR)

• Reduce delays to movements between M4, A48, A467 and the SDR

• Minimise disruption to road users during the implementation

• Enhance road safety at the junctions

• Minimise adverse impact on the environment during construction

• Increase the biodiversity of soft landscape areas within the highway boundary

The main challenges included:

• Maintaining traffic flow through the junctions during construction. This was managed by firstly simulating the modelled traffic flows to test various TM scenarios for various construction phases to ensure congestion was minimised. During construction lane closures were only used during off peak traffic times and CCTV was monitored to and traffic management available to react to any congestion issues.

• Working within areas of dormouse habitats. All works were undertaken under a license and under the supervision of an ecologists. Mitigation measures were carried out early such as selected clearance to make way for habitat planting and habitat connectivity at structure locations.

• Stakeholder management: Newport City Council, Morgan Vinci, SWTRA, Bassaleg School, Emergency Services, bus operators, Government Offices (ONS, IPO, IR), SUSTRANS, CADW & NRW.

• Managing the safety of pedestrians, cyclists and motorists. All public footpaths were maintained throughout the works and the work areas segregated from construction activities.

• Working around live buried services. This was controlled by a permit to excavate system.

• Managing public expectations and perception by routine engagement and information updates. Public information exhibitions and update presentations were held during construction.

Project management

The M4 J28 junction has been classified as the second busiest motorway interchange in Wales, where at peak times, 6000 vehicles an hour use the junction which is supporting a considerable throughput of traffic from the nearby Pont Ebbw and Bassaleg roundabouts.

The Crown Buildings are located adjacent to the Pont Ebbw roundabout that support over 2000 staff from the Office of National Statistics (ONS) and the Intellectual Property Office (IPO) and many other large-scale national businesses are located nearby at Cleppa Park.

This project, which was completed on time and under budget, used extensive collaboration between the client and the supply chain (initial collaboration workshop followed by co-location of the project team on site), along with far-reaching stakeholder engagement, comprising community meetings, public exhibition, dedicated liaison officer, use of communications database, use of driving simulator to successfully deliver substantial improvements to the traffic flow and resilience of this strategically-important junction, whilst minimising public objection and disruption to the traffic network.

The highest levels of health and safety standards were maintained with the use of considered design, regular health and safety briefings and practical measures such as Varioguard barriers to keep the public and contractors safe. As a result, the project had an accident frequency rate (AFR) of zero.

Environmental impacts were considered from the earliest planning stage and as well as achieving one of the projects’ primary objectives of reducing localised air pollution from queuing traffic, extensive environmental measures were introduced to improve the ongoing environmental performance of the junction and mitigate the impact of construction, including innovative habitat protection and improvement for protected species.

The project objectives were to include public and workforce safety, timeliness, budget management, environmental requirements and maintaining good and effective communications with the travelling public and local residents. All objectives were achieved with some innovative communication activities reaching on occasion over 10,000 road users. Excellent customer satisfaction has been achieved, with positive feedback and a client satisfaction score of 8.37/10, whilst consultation with local residents allayed concerns and influenced the design to include local improvements to light and noise pollution.

The most recent Considerate Constructors Score of 45/50 achieved by the project illustrates the lengths the project team has gone to in order to deliver this project with highest impact and minimal disruption to the local community. The project positively contributes towards all 7 Wellbeing Goals of the Wellbeing and Future Generations Act, enhancing access to employment opportunities for disadvantaged communities, improving the resilience of the road network and creating a more prosperous environment for the area.

Energy, water, material and waste management

During the design phase of the project, the team considered the forecast embodied carbon dioxide associated with both the construction and operation of the works. The road layout at Bassaleg was amended to make better use of the existing road, removing the need to construct 4 additional lanes through the middle of the roundabout, whilst not compromising the delivery of the project benefits.

A similar approach was taken at both Pont Ebbw, and J28, optimising use of the existing roads, making geometric adjustments to reduce the total surface area of the carriageway required. This will yield ongoing benefits beyond the construction phase, by reducing the area of carriageways that requiring regular resurfacing.

The project team minimised the embodied carbon during the operational phase using low energy assets, including LED street lighting, and the latest and most efficient traffic signals technology. The LED lighting also has the benefit of having a significantly longer maintenance interval, so the reduced maintenance requirements will help to reduce the total embodied carbon in the lifecycle of the asset.

The project is forecast to significantly reduce congestion, by increasing capacity to help deal with forecast demands, resulting in more efficient journeys. The design also incorporates a number of cycle routes and crossings providing safer routes for cyclists and future cycle network enhancements in the area, by future-proofing the other crossings to allow for further cycle network enhancements to be made. These measures will help to encourage more active travel journeys in the future.

People and communities

The project incorporates signalised crossings for pedestrians at every junction, providing some communities with more direct and safer crossing routes than previously available. The community of Bassaleg now benefit from an accessible and safe crossing route connecting them with the Tredegar Park Recreation ground. The crossings are designed to be upgraded to cycle crossings.

This will allow the establishment of active travel routes by Newport City
Council connecting the community at Bassaleg with the centre of Newport and the employment area surrounding both Junction 28 and Pont Ebbw. These will help people to make more active travel journeys.

The reduction of congestion will provide an air quality improvement for those living alongside and near the junctions and connecting roads by reducing the amount of stop-start traffic. The new junctions are also expected to reduce the number of collisions with improved lighting, road markings and signing guiding drivers. This safety improvement will reduce the disruption caused by collisions. Both the air quality improvement and collision reductions are expected to improve the general health of people in the local area.

The Community benefits plan for the project ensured that the local community and the travelling public were fully engaged with the project and advised of key milestone or construction events that were likely to cause any disruption. The project team were also keen to ensure that the project conformed to local and ethical procurement standards and provided where possible the opportunities for employment.

Land use and landscape

All works were carried out within existing highway boundary and no land take was required. The project designed and delivered wetland areas which acted as attenuation ponds as existing drainage outfalls were used to mitigate works in proximity to the adjacent river Ebbw.

Existing areas of Himalayan balsam was identified early on, which was eradicated in accordance with the project’s invasive species plan. Planted native trees and seeded with wildflower grass.

Ecology and biodiversity

The creation of species rich grassland mitigated the loss of other habitats. These areas created in a variety of conditions and with different floral mixes to encourage the establishment of different grassland types, which provided further ecosystem resilience and biodiversity in the Scheme and within the wider area.

This grassland creation works benefited pollinator populations in the area and thus contributed to the Action Plan for Pollinators. The trees and landscape planting also contributed to the aims of this Action Plan by mitigating for the loss of and providing additional habitats.

The historic environment

Although the scheme was confined within the existing highway boundary, works were in close proximity to Tredegar Park House, therefore some areas of groundworks required the presence of a Glamorgan-Gwent Archaeological Trust supervisor to provide a watching brief during excavation.

The water environment

The project used existing drainage outfalls to avoid working adjacent to the river and by use of attenuation ponds, limited drainage discharge to equal existing outfall capacity. In terms of the site office, all rainwater was intercepted, stored and reused for reuse for dust suppression, jet washing and plant requiring a water supply. 

Transport

To determine the effect of construction on traffic flows, we also modelled various construction phases to examine whether congestion would be a problem and then refined the construction phases to align with traffic flows which were the equivalent of existing conditions. Consequently, traffic flows improved as the scheme progressed.

The CEEQUAL process helped as a guide to look for and exploit opportunities associated with reuse of site won material, which would otherwise be disposed of off-site. Import of alternative recycled (e.g. use of steel slag aggregate in surfacing material in lieu of natural stone).

Used from the outset of an ECI contract, CEEQUAL enabled the design to be influenced by construction efficiencies. This helped reduce the cost of the construction phase and identified areas where delivery impact can be reduced (such as dust, noise, water run off). This led to a cleaner and more efficiently run project.

Materials efficiency best practice

During construction, this project used recycled material in lieu of natural stone (steel slag, recycled glass). Reuse of topsoil on site in new landscape areas. Recycled plastic noise barrier installed as a consequence of some complaints. Surplus material arising from site (e.g. excavated earth) was taken off site as beneficial reuse on other schemes which had a material shortage.