Blackfriars Station, City of London

From Workstream Pulse, Winter 2015

The £350 million Blackfriars Station redevelopment, opened last year after some five years of work, is currently the largest solar-powered bridge in the world. Comprising around 4,400 photovoltaic panels, the new station's roof has been designed to generate 900,000kWh of electricity per year, delivering up to half the station's future energy needs and cutting its carbon emissions by an estimated 511 tonnes a year. At the same time, the roof's distinctive shape has transformed the station into an architectural landmark that can be seen for miles along the River Thames, providing a bold statement of London's intention to become one of the planet's most sustainable cities.

The project at Blackfriars, built by main contractor Balfour Beatty, forms part of Network Rail's £5.5 billion Thameslink programme. It is the first station fully to span the Thames and has effectively resulted in two new stations – one on each bank of the river. The Underground station at Blackfriars was also entirely rebuilt as part of the project.

Workstream's recruitment arm provided a range of trades and labour operatives, as well as supervisory and engineering staff, to subcontractor Prater to help the company work on the highly complex roofing structure of the new Blackfriars Station. Prater's package of works included the installation of Colt louvres and soffits, a curved standing seam roof system from Kalzip, and drop down eaves that created part of the interior finish to the station.

The roof actually comprises over 100 individual roofs, each with its own gutter, louvre glazing to let in natural light, and an array of photovoltaic panels. In addition to the installation of those panels, the provision of access was required for their future cleaning and maintenance. The need to maximise the size of the panels meant space to move around on the roof was limited strictly to the areas occupied by the gutters, so a special, hinged walkway system had to be devised and installed to enable workers to gain that access.

The huge number of restrictions, challenges and health and safety issues presented by the Blackfriars Station project made it one of the most complicated jobs Prater has ever been involved in. Despite the unique logistics challenges arising from the fact that the station's platforms span the River Thames, work on the roof was completed with the station having remained open to the public throughout most of the works – a major achievement for everyone concerned.