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Digging Deep

Quicker cross-town transportation in London has been a topic of discussion for 70 years. Now, the colossal Crossrail project aims to make this goal a reality by 2018. With a price tag of nearly £15 billion, Crossrail will connect 37 stations and lay 118 kilometers of rail tracks.

 

Crossrail - Digging Deep

Crossrail’s plan to make London’s rail network fit for the 21st century is Europe’s largest infrastructure project, and it highlights several risk management challenges.

At an estimated cost of £14.8 billion, connecting 37 stations and measuring 118 kilometers (73 miles) in length, Crossrail is Europe’s biggest civil engineering project. The massive rail infrastructure program will link stations such as Heathrow airport and Maidenhead in the west with Canary Wharf and Abbey Wood in the east, and with Shenfield to the north east of the capital.

The route will provide a 10 percent increase to rail capacity in the capital, as well as bringing an additional 1.5 million people within 45 minutes’ commuting distance of London’s key business districts.

Scheduled to be completed and operational in 2018 – nine years after its May 2009 start date – five twin-bore tunnels with a combined length of 21 kilometers will be constructed under downtown London, while new Crossrail stations will be built at Paddington, Bond Street, Tottenham Court Road, Farringdon, Liverpool Street, Whitechapel, Canary Wharf and Custom House. These tunnels will weave their way between existing underground lines, sewers, utility tunnels and building foundations from station to station at depths of up to 40 meters.

Crossrail drill

The concept of large-diameter railway tunnels crossing central London to connect Paddington and Liverpool Street mainline stations was first discussed during the 1940s. The term “Crossrail” emerged in the 1974 London Rail Study Report by a steering group set up by the Department of the Environment and Greater London Council to look at future transport needs and strategic plans for London and the South East. Although current plans do not mirror the proposals, the recognition that there would be a need for more effective cross-London rail services has been around for 70 years.

Logistics at the forefront

The project creates major challenges – logistical problems are at the forefront. As one of the world’s busiest capitals, London already suffers from traffic congestion, so Crossrail’s management team has a planned the project to ensure minimum disruption to roads and to rail and Underground services.

The city is also noted for its historic buildings. Of more than 350 listed buildings that lie along the route of the railway, Crossrail needs to demolish only one of them. Allianz Global Corporate & Specialty (AGCS) is part of the group of insurers providing cover for the construction project, insuring physical damage due to the construction works and the equipment used in the tunneling process – including the eight tunnel boring machines (TBMs) – and is also involved in the public liability
insurance.

“The TBMs are powered by huge electrical motors, weigh close to 1,000 tons, and are up to 148 meters in length, and they need to have their power supply move forward with them as they bore through the tunnels at the targeted rate of 100 meters per week,” says Paul Smith, UK Engineering Underwriting Manager at AGCS.

Crossrail tunnel

Changing ground conditions

According to Clive Trencher, Senior Risk Consultant for Construction and Engineering at AGCS, the project has several major risks that need to be mitigated. “Firstly, the predicted ground conditions are likely to change from one location to the next. For example, in west London close to Paddington station the engineers will need to dig through London clay, which requires a specific set of tunneling equipment. In east London, however, engineers will need to use a slurry tunneling machine,” says Trencher.

“These present different construction and logistical challenges, such as the impact each kind of boring will have on buildings above ground and how quickly the material can be excavated, and these have to be factored into the project,” he adds.


Over the past 10 years, better risk identification and management has greatly reduced the likelihood of hazards. This is in no small part owing to better health and safety guidance, significant advances in new tunneling and construction techniques, and to a joint effort by London underwriters and representatives of the tunneling industry in 2003 to develop the Joint Code of Practice for Risk Management of Tunnel Works follow-ing a series of tunnel construction disasters that cost insurers more than US$600 million between 1994 and 2003.

Supporting new safety standards

The code stipulates that any project must have a formalized risk management procedure to identify, evaluate and allocate risk, and that risk assessments are required at each stage and summarized in appropriate risk registers that are constantly updated.

Crossrail’s legacy will ensure that key skills, sustainable working practices and risk management – as well as industry best practice – are promoted for the longterm through its Tunnelling and Underground Construction Academy (TUCA). This training facility supports the key skills required to work in tunnel excavation, underground construction and infrastructure.

Crossrail wall

By establishing TUCA, which is the only soft-ground tunneling training facility in Europe (there is a hardrock training center in Switzerland), Crossrail is contributing to the development of new qualifications and health and safety standards across the industry. Over the lifetime of the project, TUCA will offer training to at least 3,500 people in underground construction alone.

Without doubt, London’s Crossrail project will present management with many challenges over its nine-year life cycle. But given the developments in risk management in construction and tunneling in recent years, these challenges will provide an opportunity for managers to learn from the experience and constantly improve practice for future large-scale infrastructure projects.