Crossrail thinks big on sustainability12 April 2013
Large construction projects have to tick the sustainability box, but the people behind the UK’s Crossrail project have shown that it tis possible to do much more by helping to create Europe’s largest nature reserve at Wallasea Island in Essex. Urban Transport Agenda spoke to Greg Limna and Simon Phillips of Crossrail’s logistics team about raising the bar on sustainability.
Crossrail, which will connect existing rail services from Maidenhead and Heathrow in the west to Shenfield and Abbey Wood in the east, is one of London's most ambitious construction projects in decades. Its scale and complexity make it a hard task to manage, but the economic and social benefits it will bring are expected to be enormous.
Considering the many political, engineering and logistical challenges that such a project presents, one might expect sustainability to be relatively low on the list of priorities, but it is actually right near the top. In October, a 550t tunnel-boring machine (TBM) was lowered into a 40m shaft at the Limmo peninsula in Canning Town, east London, as preparations for the next stage of construction began. That TBM has since begun its journey under the River Lea towards Canary Wharf.
Similar work is underway from the western end; the excavation work from the 21km tunnel will bring up around six million tons of material and from the beginning the project's managers were keen for this material to be used in a sustainable manner.
Since 2008, Crossrail has been working with the Royal Society for the Protection of Birds (RSPB) on the design of a new nature reserve at Wallasea Island in Essex, the destination for the excavated material. The site will become Europe's largest man-made nature reserve.
"The idea started when the Crossrail bill went through parliament and we committed to finding a beneficial use for the material," says Simon Phillips, construction logistics manager at Crossrail. "When the company was set up to deliver Crossrail, I looked for a location where rail and water routes could be used to transport the material.
"The Department for Environment Food and Rural Affairs suggested contacting the RSPB and they suggested Wallasea, which is not only a very big site with easy access by water, but also one that we can control and where we can drive the programme," he adds.
In July, the first shipments of earth from Docklands arrived at Wallasea from Crossrail's transfer facility at Northfleet in Kent. As the material accumulates it will be used to create a series of cells divided by sea walls in order to provide access to the public. The ground will be shaped to provide a range of habitats including intertidal zones, marshes, wetlands, lagoons and areas above water level.
Not only will this guarantee a place for tens of thousands of migratory birds and other wildlife, including a seal population; it will also combat the threats from climate change and coastal flooding.
The project, which is on a scale never before attempted in the UK, will recreate the ancient wetland landscape of mudflats and salt marsh, lagoons and pasture, and will help compensate for the loss of similar tidal habitats elsewhere in England. Completion is expected in 2019, but the site will be open to visitors long before that, and will be a valuable resource for the local community and for wildlife from an early stage.
The material shipped to Wallasea from the Crossrail excavation sites is uncontaminated as it comes from deep beneath London and is similar in composition to the material already found in the area. It is largely made up of a Lambeth group mix, which comprises vertically and laterally varying gravels, sands, silts and clays found throughout the London Basin.
"In planning terms, it is a waste project, but it is very good material for what is needed in a fresh coastal habitat," says Phillips. "The site now is relatively poor-quality farmland that lies 2m below the high-water level and has a one-in-five-year flood risk. We are creating a new nature reserve and managing the flood risk by raising the ground."
"The project has been very well received. We could not have found a better or more sustainable home for the material. This is not about just ticking the sustainability box," he adds.
Planning and preparation
The excavation and shipping of millions of tons of material presents a huge logistical challenge. An estimated 1.4 million tons of material from the western tunnel will be taken from the tunnel entrance at Royal Oak to the Northfleet holding facility by freight train, where it will be loaded onto ships for transport to Wallasea Island.
Around 1.3 million tons from the eastern tunnels site near Canning Town station will be loaded via the Docklands Transfer site directly by conveyors onto ships at the Limmo Peninsula. The 1.8 million tons of material from the construction work in central London is to be moved to the old site of Barking power station by road, where it can be loaded onto ships.
"So, 4.5 million tons of material will go to Wallasea, which is around 75% of the material that Crossrail will excavate, though the site could take up to ten million tons," says Phillips. "This is a big logistical challenge, as we are very dependent on the loading systems and rail network, and we must ensure that the TBMs do not stop. If they do it would be very costly.
"Road trucks are easy to get hold of, so the main challenge is the loading of material onto ships. We estimate that we should only lose two or three days a year to bad weather, but we have to work around the fact that ships will only be reachable two or three hours either side of high tide," he adds.
Although the project aims to keep road transport to a minimum and 85% of its transport needs are met by water and rail, trucks are essential to the logistics process, so careful and detailed planning is required to keep loads moving. The precision of this planning was especially important given that there are always other major works underway in London and coordination between projects is essential.
"We have a traffic coordination centre where contractors log their cumulative movements," remarks
Greg Limna, head of logistics for Crossrail. "That means we can ease congestion issues and increase efficiency. We also have a driver safety training programme. These are examples of how projects on the scale of Crossrail can influence the industry as a whole by developing best practices.
"We work hard to minimise the risks. For instance, we have stockpile areas
in case ships cannot get the required access - a lot of thinking goes into what might happen. And remember, we were working during the Olympic Games, so we had to work closely with the London Organising Committee for the Olympic Games (LOCOG) to ensure that were not in their way, although we had to keep the work going," he adds.
So far, the logistics processes behind Crossrail have worked extremely well and material has been arriving at Wallasea Island without any hitches. This is testament to the preparation and planning that has gone into the sustainable aspects of the project, which are an important part of its legacy.
Raising the bar
All major construction projects aim to reuse material that is excavated. The construction of Terminal 5 at Heathrow Airport, for instance, generated more waste material than the Crossrail project will, and it was used to raise the ground at the site.
"In the heart of London that was not possible, because of the lack of space," explains Phillips. "You can't put six million tons into London's landfill space and if we had shipped it to many different places it would have been a very complex process to manage."
Crossrail is different from projects of a similar scale in that it has specifically targeted a use for the material that will have a significant and positive impact on the environment. It has proved that working with other agencies - in this case Defra and the RSPB - at an early stage in the planning process represents a major step forward in terms of putting sustainability near the top of the agenda.
Early consultation on the sustainable aspects of the project, which was key to the initial planning process, has enabled Crossrail to demonstrate that large construction projects, no matter how complex they may be, can have a positive impact not only in economic and social terms, but also in regard to the environment.
In finding the Wallasea Island site and working closely with the RSPB in order to determine the optimal use of its excavated material, Crossrail has set the standard by which large construction projects will be judged in the future. In short, the company is succeeding in setting an impressive new benchmark for industrial-sized sustainability programmes, whether their funding comes from the public or private sector.
"Our legacy is that we have shown that material can find a good home," says Phillips. "Big projects need to address the issue of sustainability now and not leave it to the contractors."