M420 Realignment?

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RoadsMaps
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Location: Geelong, Australia
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M420 Realignment?

Post by RoadsMaps » Tue Jan 23, 2018 13:14

During a standard trawling of the vicroads website, I stumbled upon a long-term plan to relieve the M420 with a new alignment from the existing route, directly North to the M1 at Pakenham. Interestingly enough, one small single-carriageway section has been built at the Koo Wee Rup By-Pass (C422), as part of the medium-term plan to build a dual-carriageway. This plan also solves the mystery as to why the M420, proper, only ever had wire barriers along the median at Koo Weep Rup when the rest of the highway has a standard, wide median.
I have not been able to find the webpage again and it is curious that no road numbering is present on the plan.

You can see the existing C422 section here: https://www.google.co.uk/maps/@-38.2055 ... a=!3m1!1e3

The upgrade map from vicroads is here: https://www.sabre-roads.org.uk/wiki/ind ... _Route.png

This proposed upgrade may also have something to do with the planned third International Airport for Melbourne in the area adjacent the road.
B110 is my local arterial.

Peter Freeman
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Posts: 625
Joined: Thu Aug 30, 2012 07:52
Location: M1-Exit E9 Melbourne Australia

Re: M420 Realignment?

Post by Peter Freeman » Thu Sep 13, 2018 02:29

RoadsMaps wrote:
Tue Jan 23, 2018 13:14
During a standard trawling of the vicroads website, I stumbled upon a long-term plan to relieve the M420 with a new alignment from the existing route, directly North to the M1 at Pakenham.

…. You can see the existing C422 section here: https://www.google.co.uk/maps/@-38.2055 ... a=!3m1!1e3

The upgrade map from vicroads is here:
https://www.sabre-roads.org.uk/wiki/ind ... _Route.png
The long-term plan is indeed to divert the Melbourne-bound M420 northwards up the recent Koo Wee Rup bypass. A gradual dualling and grade-separation of that route will eventually allow it to be M-designated.

The current outbound diverge of M420 South Gippsland Freeway from M1 will then be re-designated as M780. The more southern (and currently sub-standard) part of Westernport Highway, after M420 has diverged from it, is already designated M780. Eventually it degrades further and loses its M status.

A previous plan was to divert the Melbourne-bound M420 northwards up the C407 Clyde-Fiveways Road, but that plan was flawed. It would have avoided route 420 passing through Cranbourne but would still have left it passing through Tooradin. Also, the C407 rapidly became very urbanised owing to Melbourne's growth in the south east. The plan was abandoned in favour of the Koo Wee Rup bypass enhancement.

The wire barriers in the median of the M420 near Koo Wee Rup are not related to either of these plans. That stretch is simply an early S4 widening of the road that pre-dates most M420 duplications. I suspect it was fully new-build: the first bypass of Koo Wee Rup. A multi-fatal and well-publicised head-on collision prompted the barrier installation.

Peter Freeman
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Posts: 625
Joined: Thu Aug 30, 2012 07:52
Location: M1-Exit E9 Melbourne Australia

Re: M420 Realignment?

Post by Peter Freeman » Mon Jan 11, 2021 11:20

Work has now begun on this project. The next three years will see S2 to D2 conversion of most of the 11km 'C422' route, with five at-grade roundabouts.

Planned but not yet scheduled or funded -
1. Duplication of the existing 3km southern-most stretch (Koo Wee Rup Bypass), completing the D2.
2. New northern piece, 5km motorway, to provide free-flow into M1 westbound, avoiding the current Pakenham dumbbell interchange.
3. Upgrade to convert the southern (M420) junction to free-flow.
4. Grade separation of each intermediate roundabout.
5. Re-designation of C422 as M420.
In my lifetime? Maybe.

Project website -
https://roadprojects.vic.gov.au/project ... ad-upgrade

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