Steve Kilby

Said the following about Dover Sea Wall Project:

҉ۢ On the morning of 24 December 2015 Network Rail closed the railway lines between Dover Priory and Folkestone Central Stations after storm damage caused a progressive failure of a large section of sea wall supporting the railway.

• The Train Operating Company, South Eastern, immediately provided a replacement bus service and revised the train timetable to accommodate the rail closure.

• Network Rail had an immediate requirement to stabilise the existing wall and source a permanent solution to facilitate reopening the railway lines.

• It was recognised by both Network Rail and the Train Operating Company that this closure had a significant effect on the local economy a fact that was headlined by the local MP. This situation provided an ideal platform for all parties to practice full collaboration and provide a permanent solution in a record time.

• Costain Ltd and Tony Gee & Partners were engaged for the purpose of stabilising the existing wall and providing the permanent solution to facilitate the reopening of the railway.

• Work commenced on 26 December 2015 with the construction of a rock revetment protected by a sheet pile wall stabilising the sea wall, to enable investigatory work to be undertaken in safety.

• Even for emergency works the development period for such a project for Network Rail would be circa two years. Network Rail required permanent works design to provide the earliest reopening of the line combined with a design life of 120 years.

• Working collaboratively the team aligned the design and construction requirements with Network Rail processes, enabling the rapid execution of the works on site. The final option of a piled reinforced concrete slab protected by rock armour was agreed in February 2016.

• Early engagement of supply chain partners and alignment of individual parties’ goals ensured that the broader team collaborated bringing specialist skills to deliver a quality product within demanding programme limits.

• Working 24/7 in a constrained linear site with multiple elements of heavy plant, the project achieved an outstanding safety record with no lost time incidents.

• Railway lines were reopened to traffic on 5 September 2016, three months ahead of the publicised time frame, with all works completed at the end of March 2017.

Both Network Rail and the Train Operating Company were instrumental in maintaining local media contact, informing customers and promoting contact with local politicians to reduce the impact of the disruption to the rail service.

During the investigation and optioneering phase it was determined that a 250 metre length of sea wall of varying height between eight metres and 10 metres required reconstruction and a further 500 metres of sea wall also required rock armour protection.

The design of the section to be reconstructed was detailed so that the piled raft was entirely separate from either the original sea wall or the reconstructed rock armour to shorten the construction period to reopening the line. In addition the original sea wall had provided little protection to passing trains during heavy storm conditions and the design was required to provide additional protection in such conditions.

The programme required the designers and Network Rail to compress the design approval period whilst providing the construction team with early information to facilitate early appointment of the supply chain. The entire team fully engaged with this requirement to the point where test piles were being tested only two months after option agreement and consequently providing reopening of the railway in the shortest possible programme time.

Whilst the design of the main works was progressing the team also had to draft documentation to achieve a Marine Management Organisation Licence which would permit permanent rock armour works to commence on the beach.

Recognising the nature and volume of works to be completed essentially within a five month programme window, within an aggressive environment, the site was set up for full 24/7 working including a round the clock kitchen/ canteen to facilitate continuous hot food and welfare facilities.

Major quantities for the piled raft were 132 No 900 diameter piles 30 metres deep, 3000cubic metres of concrete and circa 800 tonnes of rebar. All major construction activities for construction of the raft were carried out 24/7. The main slab of the piled raft was cast as four 600 cubic metre pours with the pours taking place over a Saturday night into Sunday to avoid as far as possible the traffic delay prevalent at Dover because of the ferry traffic. In this respect the site had excellent cooperation from the concrete supplier and all four main pours were completed satisfactorily.

The main site works are located at Dover, at the base of the chalk cliffs. As works occurred within a spatially constrained area, it required movements around and on and off site to be carefully planned to comply with health, safety and environmental requirements. The site team were constantly challenged to come up with innovative ways to ensure the works could take place safely and on time.

A total of 36,355 tonnes of unsuitable material were moved either in or out of the site. This included approximately:

• 11,000 tonnes of recycled type 1 material and;

• 20,000 tonnes of piling horizons, concrete and spoil material.

Rather than using 18 tonne capacity trucks to move this material, impacting the already busy A20, reduce the risk of supply due to operation stack, the site team created a dedicated temporary railhead and utilised Class 66 trains. This resulted in a significant reduction in diesel fuel used (and associated carbon emissions), as well as avoiding large numbers of truck movements through Dover.

This resulted in a carbon emissions saving of 8,490 tonnes.

The programme required completion of the main civil works three weeks prior to reopening the railway to facilitate replacement of permanent way and all rail systems. This all occurred in line with the programme and the line reopened at 04:30 on 5 September 2016 with a more formal opening later in the morning including local dignitaries.

As part of the works, but not critical to reopening the line, there were ancillary items such as extensive rock armour to the beach, replacement of a failing footbridge and various finalisation works. Because of the salt laden environment the footbridge has been constructed in Fibre Reinforced Plastic which provides a structure that should not be subject to corrosive deterioration.

All of the works were completed by the end of March 2017 two months ahead of the contractual end date.

The entire works, which included significant large plant operating in a narrow corridor, was carried out with no lost time injuries recorded whilst accommodating complex temporary works because of heavy plant alongside a failing sea wall.

The project has been host to a number of high profile visitors including the Secretary of State for Transport, Network Rail CEO and local Members of Parliament. The entire team involved with the project have facilitated a truncated programme whilst maintaining high quality, civility for high profile visits all within a safe working environment.

This project has demonstrated that the entire team can work together productively and collaboratively to produce a result that has provided the best outcome for the most important stakeholder (the travelling public) being the unexpected early reopening of the rail service.“