Crossrail in London has been called one of the largest railway infrastructure projects in Europe. The project was conceived in 1941 and drafted into the city’s urban development plan in 1944 (during the Second World War!) by one of the world’s greatest urban planners, Sir Patrick Abercrombie, who planned the major reconstruction and expansion of the English metropolis even while it was being pounded by German bombardments.
Essentially, Crossrail is a new, high-frequency and high-capacity rail network comprising 136 km of track that will supplement the London Underground (which is nearing the limit of its capacity). The network will connect Reading (63 km west of London) to Abbey Wood (a suburb in the southeast of the capital), delivering a higher frequency service of up to 24 trains per hour during peak periods. Crossrail will also connect Heathrow Airport to the Eurostar high-speed line, which travels to mainland Europe via the Channel Tunnel.
After a protracted design process and numerous setbacks, construction work finally began in 2009. The eastern section entered operation in May 2015, while the western section is currently under construction.
With a total estimated cost of around 15 billion pounds, the initiative is confirmed to be Europe’s largest and most ambitious public works project of all time. Despite some teething problems, the construction of the new network is well under way and the central section is expected to enter service by 2018, as per schedule.
In drafting the contract specifications, great consideration was given to the environment, especially as regards production machinery emissions and the recycling of excavated materials, which will be reused to re-profile the River Thames and create a wetland nature reserve.
Safety standards are also very high: access to work areas is permitted only when wearing one of six different sets of personal protective equipment stipulated in the specifications, and every action is governed by strictly observed regulations posted at each construction site.
Around 8000 workers of 26 different nationalities are working around the clock in 12-hours shifts to ensure that the project is completed on schedule. The most crucial of the numerous facilities under construction (new stations, access ramps, shafts, service and emergency tunnels) is a series of tunnels that run 21 km under the heart of the city. Each tunnel comprises two parallel bores with a diameter of six metres, which are being excavated simultaneously by two tunnelling machines at a rate of 100 metres per week. As the excavation work progresses, the concrete walls are lined with concrete to strengthen them and prepare for the subsequent application of prefabricated coverings and the laying of rail tracks and service wiring.
Working away in this dark and cluttered complex of narrow, muddy tunnels up to 40 metres underground are a number of DIECI concrete mixers and dumpers, agile machines that are ideally suited to operating in such conditions.
The dumpers, with a load capacity up to 7 cubic metres, quickly transport excavated material to conveyor belts, preparing the tunnel for subsequent strengthening operations that involve lining the walls with sprayed concrete. The spraying nozzles are themselves fed by DIECI truck mixers with a production capacity of 5 cubic meters per hour, sufficient to keep pace with the eight giant cutterheads that dig 24 hours per day, 7 days per week. Thanks partly to DIECI machines, the Crossrail project is entering its final stages. Nevertheless, consultations are already underway for the construction of Crossrail 2, an additional rail link on a on a north-south axis which, if approved, will begin construction in 2019 and open in 2033!