Last reviewed 27 June 2017

Sustainability has been integral to Crossrail, London’s new railway and Europe’s biggest infrastructure project, from the start. Caroline Hand reports.

Crossrail, London’s new railway linking Reading and Heathrow Airport to the west with Canary Wharf and Shenfield in Essex, is Europe’s biggest infrastructure project. It involves the tunnelling of a new underground line across Central London, nine new stations and redevelopment of 31 existing stations. The overground rail network will also be upgraded so that today’s diesel engines can be replaced by fast, energy efficient new electric trains which will run the length of the line, bringing 1.5 million more people within 45 minutes’ commuting distance of London. The new underground line is on schedule to open in December 2018, when it will be renamed the Elizabeth Line in honour of Her Majesty The Queen.

The need for this project has been evident since the 1980s as the existing tube and rail network reached capacity. Crossrail will relieve congestion, cut journey time from the West End to Heathrow to under half an hour, and provide a much improved link between the Square Mile and the flourishing new financial district at Canary Wharf. Crossrail is expected to add £42 billion to the UK economy, which compares well with its overall cost of £14.8 billion.

Sustainability has been an integral feature of the project, with the developers adhering to a detailed code of environmental minimum requirements. While Crossrail is well known as an amazing feat of engineering, many people will not be aware that it will generate net carbon savings of 2.5 million tonnes, or that much of the tunnelling waste has been used to create an intertidal saltmarsh habitat which will be home to more than 10,000 birds.

Crossrail timeline

  • 1974: The name Crossrail first appears in the 1974 London Rail Study.

  • 1989: The Central London Rail Study proposes Crossrail, Crossrail 2 and Thameslink.

  • 1991: Government draws up a Private Bill.

  • 1994: Project dropped on cost grounds, then picked up again two months later when it becomes apparent that there is no cheaper option.

  • 1996: Crossrail must wait in line behind the Channel Tunnel and Thameslink.

  • 2000: Cross London Rail Links Ltd is set up. Consultation on the route follows.

  • 2005: Crossrail Hybrid Bill presented to Parliament.

  • 2008: Bill receives Royal Assent and becomes Crossrail Act 2008.

  • 2009: Construction begins at Canary Wharf.

  • 2012: Tunnelling begins.

  • 2015: Tunnelling completed.

  • 2018: First Elizabeth Line services to run through Central London.

An exemplary project

In sharp contrast with other major infrastructure projects such as HS2 or the third runway at Heathrow, Crossrail has not been the focus of contention, with almost no environmental objections being raised at the planning stage. This is for two reasons: first, the need for the new railway is clear and second, the environmental impact is much less than that of these other projects because most of the work is being done underground or at existing railway sites.

When London’s original tube network was created in Victorian times, there was huge disruption to Londoners. In contrast, a Crossrail engineer described his project as “doing open heart surgery while the patient is awake”. Crossrail has gone to great lengths to make sure that historic buildings are protected from subsidence, road and rail traffic keeps moving, and London remains open for business as usual. The most dramatic moment in the project came as a huge tunnel boring machine passed “through the eye of the needle” at Tottenham Court Road station, steering its way between the Northern Line tunnel below and the escalators above, with less than a metre to spare. The Northern Line kept running, although unbeknown to passengers the Crossrail engineer was anxiously watching the station’s ceiling for incoming water!

Rather than destroying valued ecosystems and landscapes, Crossrail is creating a new wildlife habitat on the Essex coast (see below), and over its lifetime the railway will save 2.5 million tonnes of carbon. All work is done in compliance with strict environmental minimum requirements.

Crossrail is not only exemplary in terms of its engineering excellence and environmental impact. It is well on schedule and is keeping within its (admittedly large) budget. The secret of its success has been the years of careful planning and project management which preceded the commencement of the tunnelling. In a 2014 report on Crossrail, Parliament’s Public Accounts Committee concluded that:

“Crossrail is a textbook example of how to focus on the essentials of programme management, including defining a realistic scope, establishing a management team with the necessary skills and securing the required funding. Two years of planning took place before the construction programme began on Crossrail, allowing the scope of the programme to be well defined, resulting in only a handful of subsequent changes being required.”

A long-term perspective

Around 78% of the carbon footprint of Crossrail is associated with operational costs rather than construction. The 2.5 million tonnes’ reduction in emissions will arise from the replacement of old diesel engines with new, energy-efficient electric trains, plus the energy-saving measures incorporated into the new stations. This is not to mention the effect of taking many cars off the road.

Not only are the new trains more efficient to run than those they replace, the railway has also been designed to use gravity in order to save energy. An upward gradient on the approach to the station, and a downward one as the trains leave, reduces the amount of power needed to slow down and then accelerate the trains.

New Crossrail stations have been built with the facility to conduct heat from underground up to commercial buildings at ground level. This will save energy throughout the lifetime of the stations (at least 120 years). For example, the maintenance depot at Old Oak Common is equipped with energy piles which, in addition to their primary function of supporting the building, also serve as heat conductors.

As well as incorporating forward-looking energy efficient designs, the whole project takes into account the likely future impact of climate change, being built to withstand higher water levels and hotter ambient temperatures.

Energy efficient construction

Significant carbon savings have been achieved through the substitution of up to 72% of cement with other materials in constructing the tunnels. Cement manufacture is carbon intensive, so replacing cement with other materials reduces the embedded carbon.

Light-emitting diode (LED) lighting with smart control systems has been used throughout the project, both at construction sites and subsequently at depots and stations. The new LED lighting installed in the eastern tunnels, which will dim to 15% when no activity is detected, uses only 12% of the electricity required by the existing lines. The Crossrail trains will also be fitted with LED lighting.

Crossrail has also taken sustainability into account when choosing fixtures such as lifts and escalators, eg the Heavy Duty Metro design is more energy efficient than existing escalators.

Waste management

The tunnelling operation has created around seven million tonnes of waste — mainly London clay — of which 98% has been diverted from landfill. Three million tonnes have been used to create a new wetland habitat at Wallasea in Essex (see below) and the rest has been used for land restoration at a variety of sites. A similar proportion of construction and demolition waste has been diverted from landfill and 80% of all this waste has been transported by rail or water.

Packaging waste has been reused or recycled, eg light fittings are supplied on a reusable plastic frame.

Air and water

Crossrail has been able to specify low-emission diesel vehicles for much of the construction work. And 84% of the equipment used in the central section has been fitted with emission controls. Particulate emissions are further reduced by the “living (green) walls” growing around several worksites.

While the tunnelling work has consumed vast quantities of water, this is treated and reused wherever possible. For example, a 465m-long train used for laying concrete needs to be washed every day. The wash water is treated and reused for subsequent washing. At the Old Oak Common depot, rainwater is harvested to wash the trains.


The Wallasea Wild Coast is a unique project, created through a partnership between Crossrail and the RSPB. A flood-prone area of former farmland has been transformed into an intertidal saltmarsh — a diverse habitat which acts as a natural flood defence. Following construction of a sea wall, waste from the tunnelling operations was deposited to create banks and lagoons. In 2015 the sea wall was breached, creating conditions for the saltmarsh to develop. The RSPB predicts that the Wild Coast will become home to more than 10,000 birds, and as early as November 2015 at least 39 different species of birds were counted at the site including the peregrine falcon, kingfisher, avocet and corn bunting. This is not to mention invertebrates and characteristic saltmarsh plants such as samphire, sea lavender and sea aster.

While the main purpose of this project is to create a wildlife habitat, it also serves as a prototype for future schemes to manage flood-prone areas as sea levels rise.

On a smaller scale, Crossrail has been able to enhance biodiversity at sites along the route, as at Ham and Wick where trees have been planted.

Sustainable design

Sustainability has been a feature of the designs from the outset. The tunnelling operations have already achieved excellent ratings under the Civil Engineering Environmental Quality Assessment (CEEQUAL ), while stations and other buildings are designed to achieve a “very good” rating under the Building Research Establishment Environmental Assessment Methodology (BREEAM) system.

Negative impacts

There were 725 environmental complaints from Londoners in 2015–16, 94% of which concerned noise and vibration as the tunnel was bored beneath Central London. The worst affected residents were given temporary accommodation or double glazing. Inevitably there have been traffic holdups and road closures, unpopular with London’s cabbies, and a small park once popular with city workers has temporarily become a construction site, but these are transitory issues.

Wider applications

Crossrail sets an example for major infrastructure projects through the quality of its forward planning. It stands in stark contrast with the construction of the Docklands Light Railway (DLR) back in the early 1990s. Because the Docklands area was not subject to any planning controls, no-one foresaw the scale of development at Canary Wharf and the original DLR proved woefully inadequate for the required huge numbers of passengers. Crossrail’s efficient construction schedule also compares favourably with that of Thameslink, whose trains still crawl through the suburbs of South London as work proceeds on remodelling London Bridge station. As with the DLR, Thameslink has been a victim of its own success and ongoing upgrades have been required to keep pace with the passenger volume.

Crossrail’s management team has participated very actively in the Major Projects Leadership Academy, which trains people to lead complex, high-risk and high-value projects. Smaller projects, such as those overseen by local authorities, cannot draw on the same resources as Crossrail and are more likely to experience difficulties. In Nottingham, for example, the extension of the tram network was subject to repeated delays. The Public Accounts Committee recommended that the Department for Transport (DfT) could share some of the expertise gained on Crossrail with smaller projects. On the practical level, Crossrail’s Tunnelling and Underground Construction Academy is training highly-skilled workers whose expertise will be transferable to projects all over the world.

With its multi-million pound investment in construction plant and vehicles, Crossrail has also had a positive impact on the supply chain, creating a market for low-emission and hybrid vehicles which have since become available to smaller buyers.

From the financial viewpoint, Crossrail had demonstrated how business and Government can form a successful partnership. The project was funded jointly by the Government, Transport for London, and the private sector. Notable contributors were Heathrow Airport Ltd, Berkeley Homes (whose housing development in Woolwich will benefit from the new tunnel under the Thames), and Canary Wharf, which along with a better transport link to Central London and Heathrow, has been able to procure a unique station surrounded by water and incorporating an orangery-style garden.

The completion of Crossrail next year is expected to be followed by Crossrail 2, linking Wimbledon with Hackney. This is not to mention the HS2 link between London and Birmingham, and future high speed rail links between the cities of the “Northern Powerhouse” and “Midlands Engine.” It can only be hoped that these forthcoming projects achieve the same high standards of project management, engineering excellence and commitment to sustainability as has been demonstrated by Crossrail.