The A412 is a road in England that links Slough and Watford. It was previously the main artery for this corridor, and continued to St Albans prior to the construction of the M25 but the A405 came and took it over. It provides interchange to the A40/M40 at the Denham Roundabout, the M25 in Maple Cross, the A404 in Rickmansworth, and the A41 in Watford.