Longitudinal axis The longitudinal axis passes through the aircraft from nose to tail.

Geography New Britain extends from 148 18'31 to 152 23'57 E longitude and from 4 08'25 to 6 18'31 S latitude.

Although they concern a relatively modest length (around 2 km) of the structure, these uncertainties are a determining factor in the selection of its longitudinal profile and of the applicable construction strategies.

The location mapping of the tunnel route is currently the subject of a study of alternatives concerning the depth of the longitudinal profile in relation to the geology along a route in an area, based on where the water is at its greatest depth, midway between the two shores.