In the Bulli Pass Strategic Review released last month by Roads and Maritime Services (RMS) was an overview of the previous studies of possible new corridors for an extension of the pass.

A 1996 study looked at no fewer than six options to upgrade the pass.

One of them featured a 330-metre tunnel as part of an approach linking the end of Memorial Drive to the pass, below the hairpin turn.

In 1998 a study looked at providing an escarpment crossing at a different location to Bulli Pass.

One of these was to link Mt Ousley Road to Memorial Drive at Bellambi through a road corridor in the vicinity of Rixons Pass Road at Woonona.

Another looked at a southern entrance through Clive Bissell Drive, Harry Graham Drive and through Mt Kembla into Unanderra.

Both were rejected as being less feasible than the 330-metre tunnel.

But the Illawarra is unlikely to see a tunnel link to Bulli Pass because of the immense cost.

According to the RMS, a 330-metre plus tunnel would cost between $1 billion and $1.5 billion to construct

In 1999, another study looked at the Memorial Drive option, that was renamed the Brickworks option, which would look at utilising several bridges.

A year later, a report identified this as the shortest and most affordable option, though it still had undesirable elements.

Then, in 2005, a report into alternative crossings ruled out Rixons Pass because the route would not attract sufficient traffic to justify the expenditure, according to the strategic review.

Considering the difficulties of upgrading Bulli Pass on the existing alignment, the 2005 plan looked at options like widening Mt Ousley Road to three lanes or a combined road and rail tunnel.

The 2015 strategic review made a recommendation for another potential route the preparation of a corridor strategy for Bulli Pass between George Avenue and Bulli Tops which is under development and due for completion by the end of 2016.