Build Magazine April 2016

Build Magazine 50 London’s oldest train station – and one of the busiest in the UK – is currently undergoing extensive rede- velopment to meet increasing trans- port demands in the capital. With the Crossrail project in full swing and an estimated 10 million people living in the capital by 2030, more must be done to address the current issues of crowding, as well as the flow and ca- pacity of an under-strength transport network. Built during the prosperous Victorian era, no one tasked with the original construction of London Bridge station could have imagined the sheer weight of demand being placed on the capital’s infrastructure in the new millen- nium. With the 2012 Olympic Games placing strain on the city’s transport links on top of a gradual population increase, few could have predicted the city’s unprecedented growth at a time when the train was seen as cutting-edge tech. But with an ever-increasing need for housing and transport to accommodate the city’s bur- geoning and ever more connected workforce, Thameslink’s £1bn investment in London transport is already beginning to bear fruit. London Bridge station brings an estimated 42 million passengers into the city each year. Despite a number of design modifications throughout the years, the station’s facilities are in need of a 21st-century refresher to consider accessibility and convenience. As part of the £6bn Thameslink programme, half a billion pounds is expected to be spent on redevelop- ing London Bridge station in order to, among other things: - Increase the number of through platforms - Construct the UK’s largest concourse - Build new entrances at street level. While the new street-level entrances on Tooley Street and St Thomas Street will allow faster access to the station at points to the north and south, it’s also expected that three of the station’s current terminating platforms will be turned into through platforms, allowing trains to go on to Cannon Street or Charing Cross, or to Blackfriars and onward. Along with the construction of what will be the largest train station concourse in the UK, the ambitious de- velopment of London Bridge rail station brings with it all manner of challenges to both form and function - one of which is the efficient implementation of a drainage system. One of the firms tasked with supplying the vital materials needed for the redevelopment is Marshalls, who are consulting on and pro- viding new drainage systems for the station’s platforms. Systems on two platforms have been installed at the time of writing while a third is under way. Considering the important role that London Bridge station plays in daily city life, the firms must tackle each logistical and design challenge with minimal disruption to operations and traffic both in and around the station. The importance of drainage in a busy public space cannot be overstated, especially where transport hazards are involved. Water must be quickly and efficiently brought away from the platform surface so that passengers can safely board and disembark from the train. All told, Marshalls will oversee the instal- lation of 4,000 metres of linear drainage along platforms and other outdoor parts of the busy station – a sizable contribu- tion made even more efficient through the use of one of their specialist water management products. In a public space, linear drainage tends to comprise a concrete channel with a metal grill on top, allowing for both the drainage of water and for foot traffic to pass over safely. As such the pieces laid down must be uniformly placed to avoid a trip hazard, and should be neatly inte- grated into an overall design that tackles the drainage needs of a public space. Birco Lite is a low capacity linear drain- age system that combines a concrete channel with grates made from a choice of cast iron, stainless or galvanised steel. While the stainless steel option was the original choice, further testing of the con- ditions in a controlled setting showed that a cast iron alternative not only provided more than ample drainage to the site but was also a more cost-effective solution over the volume of materials required for installation. Where drainage cannot be installed on a slope in order to move water away efficiently – in this case a busy train platform - there’s the option of installing a built-in fall within the concrete channel, which itself slopes gradually downward to be disposed of elsewhere. The Birco Lite system’s inbuilt fall channels increase drainage discharge capacity by improving flow rates and thereby increasing the overall discharge capacity of the system. With that design problem solved, a rather major logistical one remained: how to supply some 4,000 metres of concrete and cast iron to a London train station during operating hours. London Bridge Train Station Is Retooling Its Drainage Systems as Part of a Redevelopment to Meet Increasing Demand. Construction