Melbournes' Bay Bridge - Limestone.
Limestone between 1840's - 1920 was excavated and used as bricks for buildings around Sorrento and also exported to Melbourne after 'kiln firing' in up to 17 kilns by 1845 for use as 'whitewash' and cement and mortar for building.
Should the Mornington Peninsula alignment reserve extension be completed through to Melbourne Rd, which extends directly to Hotham Road, there could be a prospect of extending Hotham Road by tunnel under the National Park Reserve all the way to the intersection of Defence Road at the back of the Quarantine Station and the shoulder or, entrance ramp there onto the MBBridge. That would mean that the sealed Defence Road, which leads back to town and the Nepean Hwy will be able to be bypassed.
So, to be clear. It may prove to be surprisingly economic to extract limestone from a tunnel bypass that runs from Observatory Point (where the Queenscliff side can be clearly seen), back to Hotham Road which could be upgraded along with Melbourne Road and onto Mornington Peninsula Link.
The prospect of the tunnel in this situation is doubling as a mining venture in addition to passing under the The Portsea Golf Club to the National Park. Then again; I'm not responsible for planning or, implementing the project. And if you think Mornington Peninsula Link is handling the local traffic for a population of 150,000 then imagine doubling the access to 300,000 greater Geelong area residents with the MBBridge connection taking only 10 minutes to drive across 24/7 with an eTag toll fixed around $10.
Naturally it would likely be cheaper to upgrade Defence Road and join any prospective tunnel at the shortest possible distance of about 3 km from Hotham Road connection rather than all the way under as far Observatory Point. Then again, would limestone be extracted?
Would Melbourne ever be what it is today without The Bolte or, Westgate? Quick and convenient?