 The Hindhead Tunnel project shortened the route by about and routed the road through a tunnel whose northern and southern portals are at altitudes of and above sea level respectively.The need for improvements to the A3 through Hindhead had been recognised for many years with a route study being undertaken between 1970 and 1976.In 1983 some nine alternatives for the A3 were investigated by the Department for Transport, but assessment showed that only one which went around the north and west side of the Punch Bowl (the "Red Route"), crossing the Smallbrook Valley was viable.