This cache is a continuation of the M1 theme introduced by Rama497 with What's Under the M1? in Nov 2018
Do not try and access this cache from the Pacific Motorway. Access it via the marked Trailhead.
The M1 Pacific Motorway, also known by the former names F3 Freeway, Sydney–Newcastle Freeway, and Sydney–Newcastle Expressway; is a 127 km (79 mi) stretch of freeway linking Sydney to the Central Coast, Newcastle and Hunter regions of New South Wales.
Before March 1989 the freeway started and ended at Berowra. All the traffic had to pass via Hornsby to get on or off the Pacific Highway or Cumberland Highway (Pennant Hills Road).
In March 1989 the section from Berowra to Wahroonga was opened allowing traffic to bypass Hornsby.
As part of this construction, a tunnel was built at this location to allow the existing creek / stormwater channel to continue under the road and head to the Hawkesbury River.
Just on the other side of the tunnel it meets ups with the Cockle Creek, that goes all the way to Bobbin Head.
