After the Archway roundabout, the A1 enters a cutting, and becomes Archway Road. The original road north went up the very steep Highgate Hill (now the B519) to the village of Highgate. By 1808 this was proving unsuitable for increasingly heavy traffic, and a road, crossing the hill through a tunnel at a shallower gradient, was proposed by a mining engineer, Robert Vazie; a turnpike trust – the Highgate Archway Company – was set up and work started in 1810. The brick built tunnel collapsed during construction on 13 April 1812, and John Nash constructed a brick bridge, using a series of arches like a canal viaduct, to carry Hornsey Lane over what was now a cutting.