East meets west: engineering the Crossrail revolution30 August 2012
Crossrail is the biggest overhaul of London’s transport system for more than 50 years, and the extensive construction of above-ground infrastructure involved as part of the project – which will connect surrounding counties with the east and west of London – is seen as politically and economically essential. Jim Banks speaks to Eric Mumm of Network Rail, about the practical challenges that he, as the project’s engineering manager, must overcome.
When the first phase of London's high-frequency Crossrail service opens in late 2018, it will mark a new era for travelling to and through the capital, linking Maidenhead and Heathrow in the west to Shenfield and Abbey Wood in the east. Dramatically cutting journey times, it will bring an extra 1.5 million people within 45 minutes of London's business districts and is seen as essential to supporting effective cross-London public transport links for the next century.
Between 1988 and 2007, London's population grew by nearly 800,000 to 7.6 million, and by 2026 it is expected to rise to 8.7 million. The number of jobs in the capital is also expected to rise considerably, but will be concentrated in central London. About 30% of London's workforce is already located in just 2% of its geographical area - the 'central activity zone' covering broadly the West End, the City and Canary Wharf. Putting more people within easy reach of this area is, therefore, a priority.
Furthermore, demand for public transport already outstrips capacity, with extensive crowding on national rail services and on London Underground, particularly for routes towards the City, the Isle of Dogs and key rail interchanges such as Victoria and King's Cross. Demand is likely to increase further, with more than 850,000 people commuting to Greater London every day by 2025.
Putting political and economic considerations to one side, the project presents a huge and complex engineering challenge. Increasing London's rail-based transport network capacity by 10% involves constructing two 21km tunnels under the city, modernising existing stations and extending platforms in an overhaul of transport infrastructure that represents a huge investment in the UK capital.
Crossrail will be delivered by Crossrail Limited (CRL), a wholly owned subsidiary of Transport for London, with the Department for Transport as joint sponsor. CRL's aim is to provide a transport network fit for the next century, building on improvements that have already been made.
"Investing £22bn to improve London's transport infrastructure is vital to creating jobs and growing London's economy," says Mayor of London Boris Johnson, who is also the chairman of TfL. "Station upgrades for Crossrail, the Tube and the building of London's first orbital railway will deliver real improvements for Londoners, and by investing in transport now we can make the system cheaper to run and therefore cheaper to use in the long run. The building of Crossrail will deliver faster journey times, reduce crowding on the Tube and train networks, and increase capacity."
Johnson adds that a key consideration at every stage of the development and construction process is "to make sure that everything installed has as long a life as possible"; however, for the engineers delivering the upgrades, planning for the long term is a given. Traditional approaches to the construction of large structures, such as office buildings, necessitate a plan for a lifespan of decades.
"We are using the best planning technology for areas such as passenger flows, and forecasting to project figures out to 2076 to determine what modifications are needed," says programme engineering manager Eric Mumm of Network Rail, which is responsible for delivering the above-ground infrastructure for Crossrail.
"From the perspective of civil, structural and mechanical engineering, we use standard processes to ensure the work lasts for 75-100 years, as we would do for any large structure, although it is more difficult when applied to stations; for example, we are looking at provision for longer trains - up to 240m - so if carriages are added in the future, then the necessary modifications can be made easily."
Delivering the Crossrail project on time and to budget is dependent largely on the proficiency of the planners; for instance, working at stations that continue to operate during the construction phase means windows of opportunity are scarce.
"The biggest hurdle in the surface works is that it all has to be done on operational assets as we are not building new stations," explains Mumm. "We are extending platforms and making changes to the station fabric over weekends, and the stations have to be ready for the rush hour on Monday mornings. So planning is the biggest challenge.
"Some of the platforms and stations, such as Paddington, are listed structures. Slough is a Grade-II-listed building and others have an English Heritage interest, so we need their support. Also, on the Great Western and Anglia routes, the railway is not ours to fix. They have the curves and stops that Brunel built in, so we can't straighten the curves to make it a perfect railway, and that is a constraint."
Working effectively with all stakeholders - including station operators, franchise holders, local authorities and English Heritage - is fundamental to the success of Crossrail. It is by no means an easy task, given the complexity of the relationships and interests involved.
"We need early engagement with all stakeholders to come up with the best possible design to meet their goals and ours - it's all about transparency about what we want to achieve," adds Mumm. "When it comes to planning the work... we know our hold points - we know when we can stop work and leave the station, ready to allow operators to meet their goals. With major works on the railway, such as putting in new points, the work can be disruptive, so everything needs a lot of planning."
Balancing the progress of engineering work against the need to run services from stations that are being modified has been a priority from the outset of the Crossrail project.
"We are doing everything possible to ensure that the station upgrades and construction will cause as little disruption as possible," says Johnson. "They will deliver far-improved facilities and service for all passengers, existing and new. The upgrades in particular give us a great opportunity to improve existing stations, with better access and modern facilities; for example, the new Abbey Wood station will have increased capacity, improved accessibility and new entrances, as well as an interchange with Crossrail."
The impact of Crossrail will not only be felt on the transport links themselves, but also on the surrounding environment. Planning, therefore, has to take into account the wider needs of local communities and government.
"It can't be done in a bubble," explains Mumm. "We have to look at changes to the environment around the stations in terms of things like bus stops, traffic patterns and foot crossings. It is vital to get feedback from stakeholders on those issues, as well as working on areas that affect the customer experience. What used to be a suburban connection will now be linked directly to central London and underground services.
One of the big challenges, says Mumm, is getting the branding right at shared stations; for example, Ealing Broadway will have CRL, Heathrow Connect and London Underground services.
"Getting a universal branding so that passengers understand where trains go from, and when, is very difficult," says Mumm. "It is all about getting a customer information system that works for London, not just for each individual train operator."
Attempts to manage this complexity could be fertile ground for disagreements, which would slow down the progress of a project that is expected to deliver more than £1.2bn a year in transport and productivity benefits across all London boroughs. Yet these benefits are proving to be a real incentive for all parties involved to remain focused on the end result.
"The complexity of the transport system is multiplied by the addition of Crossrail, so we have to focus on the passenger experience," says Mumm. "The first goal is to meet our timetable, while engagement with stakeholders has been very positive.
"Though sometimes people have positions that are far apart, we have always strived to reach a solution that satisfies everyone. Everything has been handled in a very professional way. This is a once-in-a-lifetime opportunity, which focuses on a positive end result, and everyone wants to be part of it."