The tunnel is not open to the public; it is used only by vehicles with security clearance to drive airside.
The bored tunnel segments are precast concrete, with a 33 ft 9 in (10.29 m) internal diameter and 12 in (30 cm) thick.
The bored section of the cargo tunnel is notable among tunnelling engineers, for having been constructed with a remarkably thin cover of solid clay above it (minimum cover 1.2 m (3 ft 11 in) clay beneath the Terrace gravels).
There is one sump in the tunnel, at a low point about 300 m (330 yd) north of the south portal.
The tunnel was built by Taylor Woodrow Construction, with E&M fitout by Halliday Hall and Aerex.