In the small southwest town of Dawlish, a fateful morning brought unprecedented chaos to the lives of commuters. The picturesque seaside railway that connected them to jobs in Exeter, Plymouth, and London had been torn asunder. 

Great gouges in the rock and concrete sea wall had been ripped away and dragged into the sea. On the station platform, steel tracks hung limply over the gap where the platform once stood. The disruption to this vital rail link was not just a local issue; it reverberated through the local economy and national connectivity, exposing the vulnerability of coastal infrastructure in the face of extreme weather events.

The Dawlish Seawall Disaster

Dawlish, a charming coastal town in the southwest of England, became the symbol of the challenges faced by communities that rely on coastal railways. The severity of the damage left commuters stranded and the local economy bleeding at an estimated rate of over £20 million a day. Roy Hickman, Senior Rail Consultant for Fugro, emphasises the critical role of the Dawlish rail line, “It’s one of the main arterial routes to the south of England downtown to the Cornish Peninsula. And when you use that there is no viable alternative, certainly by rail.”

As Matt Barnes, head of strategic service development for Great Western Rail says about how vital that link of rail is to the local community “It’s a vital link for local travel in the area, we have many hundreds of students who go to Exeter college every single day into Exeter, we have hundreds of slightly younger schoolchildren, children who go to Tor Grammar School. So it’s a vital line for many people’s livelihoods, their education, and of course, their holidays.”

The Herculean Effort to Reopen the Line

As soon as the storm subsided, Network Rail mobilised a team of 300 to work around the clock to restore the rail connection to the southwest. Their first priority was to prevent further loss of the railway line. Barnes, Head of Strategic Service Development for Great Western Railway, recounts how they used innovative engineering methods, to stabilise the damaged section and divert the transatlantic cable running alongside the railway.

“Their first priority was to stem the, the, the loss of more of the railway line and they and they, they used a bit of kit that they actually had already got for engineering works that were going on a little bit further up the line at the tunnel to spray concrete in there. One of their other great challenges was to divert the famous transatlantic cable. There is a cable that provides digital data connections between the US and the UK and has done for generations and generations along the railway corridor. So restoring that cable was an early priority, because you can imagine that that was of pretty high value to the economies of our respective countries.”

However, even as repair work was underway, another powerful storm struck Dawlish, causing further damage to the sea wall. Shipping containers were deployed to provide protection to the damaged sea wall, reflecting the determination of the railway workers to overcome the elements and keep the line running.

Rebuilding the Dawlish Seawall

Just two months after the initial storm left the rail hanging precariously, the train service through Dawlish resumed. The resilience and hard work of the railway engineers were celebrated, and even then-Prime Minister David Cameron visited Dawlish to mark the line’s reopening. But the issue of the sea wall remained.

Protecting Dawlish and its vital rail line from future storms required a new sea wall. While rebuilding such a sea wall presented numerous challenges, Jack Brookes, Senior Agent for contractors BAM on the Dawlish sea wall project, recalls the difficulties of working adjacent to a live railway on the beachfront and having to preserve the historic station building.

“One of our main challenges in working in this area was working adjacent to a live railway on the beach front. Then the fact that the station was a listed building, how close we were building to the existing seawall as well. So we have to look at all the temporary stability of the existing wall. While we’re undertaking the delivery of the permanent works. There’s a lot of temporary works implemented to make sure that didn’t collapse the existing wall.”

The Innovative Solution: The Wave Walker

Traditional construction methods were insufficient for the Dawlish sea wall project, especially due to the challenges of working on a beach with changing tide levels and hostile weather conditions.

 To overcome these issues, the project turned to an innovative solution: the Wave Walker. Developed in collaboration with Dutch marine contractors Van Oord, the Wave Walker resembles a giant metal spider with eight legs that can manoeuvre across the seabed. It uses a unique jacking mechanism to move and work effectively in shallow waters.

Zac Smart, technical manager at Fugro and barge master of the Wave Walker during the Dawlish project, describes its capabilities. “So Wave Walker one is 32 metres squared. And she has 40 metre legs that are 1.8 metres in diameter. She’s capable of carrying 400 tonnes with a normal payload. Once in a jacked condition, then she moves by. In simple terms, four legs are on the ground at any time. And then you would lift the other four legs and you can slide those anywhere between zero and four metres. So a complete stroke is four metres.”

The Wave Walker’s design enables it to walk like a crab through the waves, with its hull continuously raised above obstacles. Its adaptability to different water depths and hostile environmental conditions made it the perfect choice for the Dawlish project.

The Advantages of the Wave Walker

Wave Walker proved to be a game-changer for the Dawlish seawall project. It could work continuously, without the constraints of tides or bad weather, which often halt conventional construction. The ability to move the Wave Walker rapidly allowed it to significantly surpass its initial target, installing up to 10 metres of piles per day

“if you had a conventional jack up, you might have been able to move in there when there was no sand, you had more water. The weather changes, the sand comes back, well now you’re stuck!” Smart explains.

Using the Wave Walker they were expected to install 283 piles over 90 days. However the pile installation moved quickly and ahead of schedule. After 90 days they managed to install an extra 42 piles across the sea wall.

Compared to using a traditional jack-up barge, Smart estimates that the Wave Walker saved around £7 million and 3 months in construction time, but that doesn’t take into account the potential down time a traditional jack-up might experience due to adverse weather.

“We arrived on site in November, and we were finished towards the end of February. If you had been relying on a conventional jack up, you would have still been there until the summer.” Smart explains.