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The Day Part Of Southwark Bridge Exploded

Kingsway resembled Mordor High Street last week, as acrid smoke and jets of flame belched from its drains and manholes. The cause has still to be fully sleuthed, but something was clearly amiss with the utilities beneath the surface.

Pavement explosions are regularly in the news, and might seem like a modern phenomenon. Yet the flagstones of London have been prone to fiery ejaculations since the first modern utilities were laid. One particularly dramatic example occurred on Southwark Bridge, in 1895.

The gaudy turquoise crossing we see today is the second Southwark Bridge. The first, opened in 1819, was something of a landmark thanks to its 73-metre arch of cast-iron — the longest span in the world at that time. Press reports describe it as ‘a stupendous structure’... ‘charming, graceful and fairylike’. It was even dubbed a modern Wonder of the World.

The original Southwark Bridge, Wikimedia Commons.

Nevertheless, the bridge was a failure. Fifty people lost their lives during construction, an utterly unthinkable tragedy today, and grim even by the standards of the time. Cost over-runs meant that the architect, John Rennie, had to sue the Southwark Bridge Company for his fee. Nobody wanted to pay the inevitable tolls, imposed to recoup the financial loss.

Then, on 1 February 1895... Boom! The bridge partly exploded. As depicted below, a huge eruption sent flagstones flying at the south-west corner (outside today's Ofcom headquarters). A chain of fireballs then raced along the opposite side of the bridge. Two men shovelling snow were slightly injured, along with three pedestrians. Chunks of masonry fell into the Thames, fortunately missing any river traffic.

Image from the Illustrated Police News, 9 February 1895. (c) The British Library Board, all rights reserved.

News of the explosions passed around the world like Chinese whispers; the Australian press reported that the whole bridge had blown up. Fortunately, the damage was superficial and soon repaired, but many wondered at the obvious danger to the public from future explosions.

A report was immediately commissioned, and delivered by Major Philip Cardew, a former Royal Engineer and electrical advisor to the Board of Trade. Cardew had presided over an enquiry into a similar incident four months before when a utility explosion had killed a horse on Cannon Street. He found that gas from a cracked pipe beneath the pavement had accumulated in electrical boxes and pipes. This would normally seep out into the roadway, but the February frost had made the ground impermeable. An electrical spark ignited the gas, sending a shockwave along the bridge. Cardew's recommendations included more sophisticated ventilation for under-pavement utilities, and the use of less-combustible materials.

The City of London Electric Lighting Company was slow to respond but eventually employed "a large staff of men to push forward the works". That push would not quickly yield results: "from their nature and extent... some time must necessarily elapse before they are completed". Evidently, the problem was never entirely eliminated, and we still live with the scourge of pavement explosions 110 years later.