The road was diverted and upgraded in 1956, the same year as construction work started on the airport: the section running northwards from Crawley became a dual carriageway, and approximately 200 yards south of the village crossroads, the road was diverted sharply to the east at a new roundabout, continuing straight across an undeveloped section of the heath and around the newly defined perimeter of the airport until it met the London–Brighton railway line, at which point it turned north again.