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Walking in the air

Glass flooring has completed the all-round raven’s eye view from the high walkways on Tower Bridge

The last time they were famous they had the 2012 Olympic rings hung from them. Now the high level walkways at London’s Tower Bridge are even more connected to their city: their floors have been cut open to reveal the view below. Not only that but the glass has hit the headlines for being shattered by an empty glass beer bottle – though as any architect knows the cracking of a single sacrificial layer will not plummet visitors into Thames 42m below, in this case thanks to four more layers of glass.

Each of the two walkways has a 11.5m by 1.8m wide opening with six glass panels held in a 1000kg carbon steel frame, the result of a careful negotiation by architect Purcell with two boroughs for this grade 1 listed structure. Underneath the glass the original 1894 structure, designed by architect Sir Horace Jones and engineer Sir John Wolfe Barry, is still visible, criss-crossing the view of the road, the Thames and the occasionally opening bridge, below. 

  • Cutting into the floor of the two walkways but leaving the 1894 steel structure intact.
    Cutting into the floor of the two walkways but leaving the 1894 steel structure intact. · Credit: Barksy Media + Tower Bridge Exhibition
  • Looking through the glass insertions to the Thames 42m below.
    Looking through the glass insertions to the Thames 42m below. · Credit: Barksy Media + Tower Bridge Exhibition
  • The view below – unless you catch the bridge as it opens.
    The view below – unless you catch the bridge as it opens. · Credit: Barksy Media + Tower Bridge Exhibition
  • Fascination or fear visitors can skirt around the timber edges of the glass if they are feeling queasy.
    Fascination or fear visitors can skirt around the timber edges of the glass if they are feeling queasy. · Credit: Barksy Media + Tower Bridge Exhibition
  • Many people don't even know the high level walkways are accessible.
    Many people don't even know the high level walkways are accessible. · Credit: Barksy Media + Tower Bridge Exhibition
  • Visualisation of the Tower Bridge walkways from below.
    Visualisation of the Tower Bridge walkways from below. · Credit: Purcell Architects

Installing the glass panels took six weeks above the busy road into the City. Closures were needed just to put the gantry into place – though in fact it was primarily decorative work that had to be completed from the gantry platform. The panes of glass were carried to the walkways in the large lifts that bring up exhibition visitors every day. The glass floors move as an integral part of the bridge as the base frame is epoxy grouted to the original plate floor and the structural mastics allow the necessary tolerance for both thermal and physical movement.

  • Plan showing lattice structures of the walkways.
    Plan showing lattice structures of the walkways. · Credit: Purcell Architecture
  • Design for walkway section.
    Design for walkway section. · Credit: Purcell Architects
  • Detail of junction of insertion.
    Detail of junction of insertion. · Credit: Purcell Architects

Along with the release of an app showing the bridge being raised in its full panoramic glory, the Tower Bridge Exhibition management hopes that the re-envisaged walkways at the centre of the experience will increase the visitor numbers from the 600,000 a year it currently has through its doors.