The engineering feat of pulling 300-tonne bridge sections across the Thames

Science · Published 20 October 2026 · Updated 22 October 2026 Swipe more like this →

In short: How do you build a bridge in a city where the ground is a minefield of unexploded bombs and the subway runs just feet below the riverbed? The Golden Jubilee Bridges were constructed using a high-stakes method of incremental launching, moving massive steel sections across the water without stopping the trains above.

The construction of the Golden Jubilee Bridges (completed in 2002) faced extreme logistical constraints. Due to Bakerloo line tunnels situated just inches under the riverbed and the threat of unexploded World War II bombs within the Thames mud, construction teams faced significant hazards. Because the London Underground refused to accept the risks of heavy machinery near these tunnels, the design had to be modified to move the north side support structure out of the river bed and onto the Victoria Embankment. Excavation near the tube lines was eventually performed by hand during scheduled closures.

To span the river, engineers used a technique called incremental launching. A 300-tonne steel truss measuring 250 metres (820 feet) in length was employed to drag every 50-metre (160-foot) segment of the 300-meter (980-foot) span over the water. Six temporary piers of concrete and steel provided stability as this procedure occurred five times to place the decks in situ. Once in place, the seven 25-tonne pylons were raised over two weeks, and the decks were jacked up to connect with the cable stays.

The structural physics of the bridges rely on a complex system of tension and compression. The decks are supported by inclined, outward-leaning pylons. They are suspended from fans of 180 slender steel rods (deck stays) on each deck, totaling over 4 kilometers of cable. Because the pylons lean, the backstays are kept under tension. The entire structure is secured to the existing Hungerford Bridge foundations using steel collars and tie-down rods, exploiting the balance of forces between the pylons, stay rods, and struts.

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