The London Tube
The London Tube is the oldest underground railway in the world. The first section was opened in 1863 and in 1890 there was the introduction of electric trains. The entire network is commonly referred to by Londoners and in official publicity as the Tube. Though that term originally applied only to the deep-level bored lines, which trains of a smaller and more circular cross-section run along, to distinguish them from the sub-surface “cut and cover” lines that were built first.
Today London Underground serves 270 stations and has 402 kilometres of track, making it the second largest metro system in the world in terms of route miles, after the Shanghai Metro. In 2007, more than one billion passenger journeys were recorded, which qualifies it as Europe’s third busiest metro system, behind Moscow and Paris. The Tube has become an international icon for London, and the Tube map is considered a design classic, having influenced many other transport maps worldwide.
Strengthening by overnight installations
But how can the Tube be maintained to endure the tremendous constant loads it has to bear? Let us take a closer look north of the River Thames, where Embankment Gardens are supported by iron beams above the covered ways. Though found to be adequate under normal load conditions, they were considered in need of strengthening to accommodate any unforeseen future loadings. Covered ways either side of Embankment Tube station have been strengthened using Sika CarboDur UHM plates provided by Sika UK.
London Underground had to ensure the chosen repair solution would have minimal impact on the tunnel headroom and could be installed overnight, with the service’s passengers entirely unaware of the vital work being undertaken. Since a reinforced steel element was deemed too thick to be a viable option, a system that was thin yet extremely tough was required.
Use of ultrahigh modulus composite
An ultrahigh modulus carbon fibre reinforced polymer (CFRP) system, Sika CarboDur UHM is designed for high performance and demanding reinforcement applications. With over 1,300 metres of Sika CarboDur UHM plates applied, it has marked the UK’s largest ever project to use ultrahigh modulus composite. Delivered over a six-month period, the project was successfully finished to the highest standard with the contractors reinforcing an average of two beams per night on-site.