People could have driven between England and France across a huge suspension bridge if plans had been approved, records show.
Plans for the Anglo-French bridge have been preserved
A submission for a £3bn three-lane motorway link was made to transport officials in April 1981, files released by the National Archives show.
Engineering group LinktoEurope estimated motorists would pay a £5.60 toll charge and lorries £8 to cross.
The records did not show how seriously the government considered the plans.
Margaret Thatcher's government was discussing the Channel Tunnel project when the bridge plan was submitted for consideration.
Dismissing the option of tunnelling under the Channel as "impractical", the LinktoEurope proposal suggested a bridge spanning 21 miles from Dover or perhaps Folkestone.
The bridge, 220ft above Channel waters, would bring in a revenue of up to £220m a year, the group estimated.
Engineers conceded the huge pylons on which the bridge would rest could make navigation of the Channel difficult for ships.
However, they said the structure would be sturdy enough so that traffic above would be unaffected if a vessel ploughed into the struts.
The Channel Tunnel opened in 1994 and took eight years to be built.