Southsea Coastal Scheme, Portsmouth, UK

NEC contracts are being used to deliver the UK’s largest local-authority-led coastal defence project. Client Portsmouth City Council let the £200 million Southsea Coastal Scheme to VolkerStevin Boskalis Westminster Joint Venture under an NEC4 Engineering and Construction Contract (ECC) Option C (target cost with activity schedule) in September 2019.

The 4.5 km scheme stretches along the southern coastline of Portsea Island, from Old Portsmouth in the west to Eastney in the east. It is being progressively designed and built as six separate frontages. On completion in 2028, the scheme will reduce the flood risk to more than 10,000 homes, 700 businesses, 74 listed structures and three scheduled monuments.

The NEC project manager is Coastal Partners, a local authority alliance of Chichester District Council, Havant Borough Council, Portsmouth City Council, Gosport Borough Council and Fareham Borough Council. The designer Royal HaskoningDHV was engaged under an NEC3 Professional Services Contract (PSC) while cost consultant AtkinsRéalis and archaeological consultant Wessex Archaeology were appointed under NEC4 PSCs. Subcontracts were generally let using back-to-back NEC4 Engineering and Construction Subcontracts (ESC).

Six frontages

Frontage 1 at the western end, which includes Portsmouth’s sixteenth and seventeenth century military defences Long Curtain, King's Bastion and Spur Redoubt, started as Covid-19 hit but was still completed on programme and budget in February 2023. The work involved demolishing and rebuilding the seawall, increasing the height and width of the promenade, installing 525 m of sheet piling, and placing 11,474 t of Norwegian rock and 5,700 t of concrete. A total of 136 precast concrete parapet units were installed along with new bridges, lighting, plants, seating, rockpools, parking spaces and other public realm improvements.
 
Frontage 4, the area around Southsea Castle, was completed in May 2024. This included placing 145,000 t of rock, building a 96 m long rock groin to reduce beach erosion and creating a new split-level promenade known locally as ‘the theatre of the sea’. Frontage 5, between the Pyramids Centre and Speakers’ Corner, was completed in December 2024. In addition to raising the promenade by 0.6 m, the frontage included a stepped revetment leading to a managed beach, a low set-back wall and refurbishment of Grade 2 listed shelters and lamp columns. 

In October 2024, work started on Frontage 3, the area around Southsea Common, and this will be completed in summer 2026. It involves building a combination of a stepped and rock revetment, with a managed beach in front and a raised promenade and embankment sloping into the common at the back. Frontage 6, the area along South Parade Pier and Canoe Lake, and Frontage 2, the area around Clarence Pier, are due to be completed on programme and budget by 2028.

Proactive project management

Chris Koster of Coastal Partners says the local authority alliance has adopted NEC as its standard delivery vehicle. ‘The NEC contract suite is clear and concise, allowing proactive project management and inclusive and collaborative partnerships to be established.’

He says the NEC forms are more than just conditions of contract. ‘On the Southsea Coastal Scheme they act as positive project management tools with a collaborative and fair ethos throughout. The flowcharts and workflows, including periods for reply, ensure correct and timely decision making and minimise the risk of misinterpretation. This sets the basis for clearly understood partnership working and is ensuring successful project delivery.’

Koster says the scheme is being delivered by an integrated delivery team. ‘In line with the NEC requirement to act in a “spirit of mutual trust and co-operation”, this allows for a truly collaborative working environment, with the best people in the right spaces to give the best outputs.’

He says the key to the success of the whole project is the NEC-inspired collaboration. ‘There has been collaborative working by all parties involved, respecting and understanding the NEC processes and working together to resolve issues, risks and opportunities quickly and efficiently.’

Early Contractor Involvement and sectional completion

Koster says the construction contract included Option X22 on early contractor involvement and Option X5 on sectional completion. ‘This allowed for sections of the project to be delivered while other stages were being designed, with lessons learned in the earlier delivery stages being incorporated into designs for later stages.’
He says having a single contract with the ability to issue multiple stages also gave commercial surety to the supply chain. ‘It allowed partners to be brought into the project from day one and stay committed until completion. The proactive NEC contract model then facilitated the collaborative working required for success all the way through the supply chain.’

Frontage 1 was highly commended for the Placemaking Project of the Year in the 2024 British Construction Industry Awards.

Benefits of using NEC

• NEC requirement to act in a ‘spirit of mutual trust and co-operation’ allowed for a truly collaborative working environment, with the best people in the right spaces to give the best outputs.
• NEC-inspired collaborative working led to all parties respecting and understanding the NEC processes and working together to resolve issues, risks and opportunities quickly and efficiently.
• NEC flowcharts and workflows, including periods for reply, ensured correct and timely decision making and minimised the risk of misinterpreting clauses. 
• NEC Options X22 on Early Contractor Involvement allowed for sections to be delivered while other stages were being designed, with delivery lessons learned incorporated into later designs.
• NEC Option X5 on sectional completion allowed partners to be brought into the project from day one and stay committed until completion.