Unfortunately it exploded, killing a policeman. The accident discouraged further development until the era of the internal combustion engine. Modern traffic lights are an American invention. Red-green systems were installed in Cleveland in 1914. Three-colour signals, operated manually from a tower in the middle of the street, were installed in New York in 1918. The first lights of this type to appear in Britain were in London, on the junction between St James's Street and Piccadilly, in 1925.

They were operated manually by policemen using switches. Automatic signals, working on a time interval, were installed in Wolverhampton, in 1926. The first vehicle-actuated signals in Britain occurred on the junction between Gracechurch Street and Cornhill on the City, in 1932. By some strange quirk, these were also destroyed by a gas explosion. Standardised red-amber-green signals are now universally adopted.

The book Eureka (ed. Edward de Bono, Thames & Hudson, 1979) says: 'Boring standardisation has replaced such eccentric specimens as the elegant gilded columns of Fifth Avenue, each surmounted by a statuette, and the traffic lights of Los Angeles which, not content with changing mutely, would ring bells and wave semaphore arms to awake the slumbering motorists of the 1930s.'

According to theguardian