Canberra97,
And a long time since you were there too if you believe that DaveReidUK is talking about the two old bike/pedestrian tunnels. These have always been there running parallel to the main tunnels. They were made available for cars and taxis years ago to increase the flow. That's why there are free buses around the airport cos you can't access the Central Area any other way. No bikes nor pedestrians allowed.
Now...back to the apron access tunnels and their former and current us. Anyone?
S