ICE Bridge Month: Bridge #12 – Millennium Footbridge

In October 2017 I was invited to speak at the Institution of Civil Engineers annual awards about the Barangaroo Reserve Project in Sydney. On my list of things to see on this very short trip was the Millennium Footbridge in London.

I arrived a day before the awards night and went for a very long walk along the River Thames, starting at the Westminster Bridge and finishing at the Tower Bridge. There are some truly magnificent pieces of bridge engineering along this route; from wrought iron, to steel to concrete box girders.

My favourite, the Millennium Bridge. It is modern but respects the past technology for suspension bridges by pushing the limits. The bridge was the result of a design competition in 1996 and was the first bridge to be built across the River Thames in over 100 years.

On approach, the bridge is almost invisible. I struggled to pick it up on the skyline with the backdrop of the city as I walked through the underpass along the quay at Blackfriars Bridge.

The bridge has two piers in the river and has tree main spans of 81 m, 144 m and 108 m. The deck is 4 m wide and connects directly with the views of and linkage to St Paul’s Cathedral. When you walk across, the cathedral is beautifully framed by the bridge supports.

The southern abutment is spectacular. You can clearly see the resolution of forces that keeps the bridge standing. Engineering at its best. The mass of the abutment anchors the bridge. The cable profile is so flat across the bridge , as you walk across it the views are not impeded at all.

It is well known that when the bridge opened, there was an issue with lateral movements of the structure with large crowds. Locally I have heard the bridge is called the Wobbly Bridge and not by its actual name. Despite the issues with “wobble” when the bridge opened, the remedial works undertaken to dampen the lateral excitation of the structure have been seamlessly integrated to the structure and does not detract in any way to the original design.

The design was undertaken by Foster and Partners, Sir Anthony Caro and Arup. There are some beautiful sketches from Foster and Partners' website that I recommend you look at. 

This is truly an innovative design. The design of a suspension bridge is pushed to demonstrate that a very shallow cable profile can work. With innovation always comes risk. When risk is realised, there are many learnings for the engineering community. This makes us better engineers.