John Gorton Drive Bridge 2021 update

The planning for the John Gorton Drive Bridge has come out of the shadows – The funding promised at the ACT Election has been announced and the development application documents have been released. The construction costs will be about $177 million (June 2020 estimate).

4 more years

John Gorton Drive Bridge is a strategic link connecting the Molonglo Valley estate development on the north with the south side of the Molonglo River. Belconnen lies about 10 km north of the river and Weston Creek just to the south.

Timeline for the development

“The project could be completed by 2024 or 2025.

The 1.7 km final Stage 3C will connect Stage 2A, completed in 2018, and 3B, currently under construction, and includes a 227.5-metre long, high-level bridge which will be capable of carrying light rail, and link back up with the northern section of Coppins Crossing Road.”

Government moves ahead with Molonglo River bridge, The RiotACT Ian Bushnell, 16 December 2020

Detail design in progress

Transport and City Services Minister Chris Steel said detailed design work should commence in 2021 and take about 12 months to complete, followed by a two to three-year construction period.

He said the (ACT) government’s Jobs and Economic Recovery Plan included the $175 million for the final stage of John Gorton Drive. The Commonwealth Government later contributed $87.5 million to the project in its 2020-21 Budget.

Government moves ahead with Molonglo River bridge, The RiotACT Ian Bushnell, 16 December 2020

Underpass not certain

The John Gorton Drive is a wide and busy arterial road and crossing it is difficult for pedestrians, cyclists and people on scooters. The John Gorton Drive Bridge development application shows an underpass between the suburbs of Molonglo and Denman Prospects (see below). The underpass is, however, not part of the development application.

A development application is not for the bridge construction but rather for its approval. If we want the underpass it must be included in the detail design happening right now.

There is no guarantee that we will get the underpass or that it is particularly suited, i.e. safe, for cyclists. For example, an underpass on the north side of the Molonglo River on John Gorton Drive was never realised, although schools will be built adjacent to this road.

Molonglo Valley planning in 2021

Planning the cycling infrastructure

Recently a development application was released for Denman Prospect beside the bridge showing the active travel routes in the area (this is a requirement of every estate development). The John Gorton Drive Bridge site is a hole in the landscape. The development of the area around the bridge in both Denman Prospect and Molonglo are being deferred until the bridge will be completed.

Cyclists’ Main Community Routes are important for getting around and serve to thread suburbs together in hopefully logical and sensible ways. Principal Community routes are for cross city travel and most commonly used for work and education commuting. They are commonly known as CBR Cycle Routes and at this time there are few and funding is poor. The 2020-2021 ACT Budget has no funding for Principal Community Routes. The ACT Greens at the 2020 ACT Election promised a cycling “revolution”. Hopefully, their plans will be funded in the next 2021-2022 ACT Budget. This budget must be in the works now.

Principal Community Route (PCR) –A subset of Main Community Routes (MCR) that form direct links between town centres. There are routes that are to include route labels and branding.

Active Travel Facilities Design – Municipal Infrastructure Standards 05 (MIS05) (ACT Government, April 2019)

Main Community Routes through the Valley

The Molonglo Valley is a 50 m deep ditch. Coppins Crossing at river level is 90 m below William Hovell Drive. Riding to Belconnen from Coppins Crossing is roughly a 130 m climb. Compare this to riding from the gates of the National Arboretum to Dairy Farmer Hill, which is a climb of almost exactly 100 m. The John Gorton Drive Bridge flattens the river crossing by about 24 m – the separation between the bridge deck and the river level. In comparison, the nearby Butters Bridge has a 25 m deck height.

Height Ridge heightCoppins Crossing levelRise
William Hovell Drive642 m512 m130 m
Coulter Drive655 m512 m143 m
Aranda CBR C5639 m512 m127 m
Ridge height between Belconnen and Molonglo Valley at key points. Height data from the Digital Elevation Model (DEM), OpenStreetMap.

Coppins Crossing has an altitude of 512 m above sea level using the data from the Digital Elevation Model (DEM) from OpenMTBMap (a OpenStreetMap derivative). From this source we also know the elevation on the ridge between Belconnen and the Molonglo Valley at the most common crossing points. This differs to the development application as the survey for the development application is much more precise (a few metres versus a few millimetres).

LevelsHeight
Molonglo River506 m
10 year flood level510 m
100 year flood level513 m
Dam break flood522 m
Bridge deck level530 m
Height levels for flood. John Gorton Drive Bridge profile from DA. Precision +-0.5 m

We want Main Community Routes to be as direct and flat as possible with gradients of no more than 5% (Austroads design standard AGRD06A). Such low gradients can be difficult to achieve across low level river crossings but are possible across high level river crossing over bridges. The gradients on the Coppins Crossing Road reach 10%.

Gradient profile of John Gorton Drive, Molonglo Valley
Gradient profile of John Gorton Drive, Molonglo Valley. The gradient profile is measured with the Garmin Edge 520 altimeter along John Gorton Drive, crossing the Molonglo River at Coppins Crossing. Image: VeloViewer

The most direct and flattest route between the group centre at Molonglo and West Belconnen is through an underpass on the approaches to John Gorton Drive Bridge, across Butters Bridge, through the Namarag Molonglo Special Purpose Reserve, past Whitlam and along Deep Creek. This route is shown by the BLUE line below. The RED line shows the location of the John Gorton Drive Bridge.

Molonglo Valley around John Gorton Drive Bridge showing Main Community Routes
Molonglo Valley around John Gorton Drive Bridge showing Main Community Routes. Source: Denman Prospect Development Application, February 2021.

A recent Denman Prospect Development Application from February 2021 shows the Main Community Route crossing the Molonglo River at a low level crossing west of Namarag Molonglo Special Purpose Reserve. This route is more arduous and steeper than the Butters Bridge alternative suggested above.

Butters Bridge, Molonglo River, Molonglo Valley, Canberra
Butters Bridge – cost $7.7m, length 242 m and 25 m high over the Molonglo River, Molonglo Valley, Canberra

As discussed previously, it is necessary to reserve such corridors if they are to have any chance of being included in the estate development application for Molonglo or Denman Prospect. The current development application for the west section of Denman Prospect is incomplete as it does not include the John Gorton Drive Bridge (released in 2020).

Denman Prospect and Mount Stromlo, Molonglo Valley, Canberra
Major Community Route via low level river crossing, Denman Prospect (foreground) and Mount Stromlo (background), Molonglo Valley, Canberra

Bridge view

Views of the bridge captured from the development application.

John Gorton Drive Bridge bike path view
John Gorton Drive Bridge bike path view
John Gorton Drive Bridge side view
John Gorton Drive Bridge side view
John Gorton Drive Bridge side view across river
John Gorton Drive Bridge side view across river
John Gorton Drive Bridge shared path lighting
John Gorton Drive Bridge shared path lighting
John Gorton Drive Bridge side screen
John Gorton Drive Bridge side screen

Features

The John Gorton Drive Bridge features a 3 m wide shared bike path on both side of the roadway.

John Gorton Drive cross section 3m shared path
John Gorton Drive cross section with a 3m shared path

The John Gorton Drive is a wide road and a barrier for pedestrians and cyclists moving between the adjacent suburbs of Denman Prospect and Molonglo, which includes the town centre. An underpass is proposed close to Butters Bridge, but is not part of the John Gorton Drive Bridge development application. It would need to be included in the detailed planning in 2021.

John Gorton Drive Bridge pedestrian underpass
John Gorton Drive Bridge proposed pedestrian underpass

Whitlam will end in the footsteps of the bridge. The bridge construction appears to be from the south side. The Whitlam development may progress dependent on the staging of road works on the north side.

John Gorton Drive Bridge locality map
John Gorton Drive Bridge locality map

The construction method for the bridge is similar to the one that was used to construct Butters Bridge, but the design is only optically similar. The girders will slowly be pushed over the gap.

John Gorton Drive Bridge construction girder launch
John Gorton Drive Bridge construction girder launch

The John Gorton Drive Bridge is a box girder design. Three girders support the road with a shared path on each side. The light rail is supported by another two in the middle.

John Gorton Drive Bridge cross section 3m shared path
John Gorton Drive Bridge cross section with a 3m shared path

Coppins Crossing Road remains for river access.

John Gorton Drive Bridge ariel view
John Gorton Drive Bridge arial view

The bridge has a low profile design with the road deck 24 m above the river and 8 m above the expected flood level should the Scrivener Dam fail. The central span is 93 m and those adjacent shorter.

John Gorton Drive Bridge profile from DA
John Gorton Drive Bridge profile from DA
Coppins Crossing Road, Molonglo River, Molonglo Valley, Canberra
Coppins Crossing Road, Molonglo River, Molonglo Valley, Canberra

4 Replies to “John Gorton Drive Bridge 2021 update”

  1. I am struggling to understand your comments about underpasses under John Gorton Drive.
    “For example, an underpass on the north side of the Molonglo River on John Gorton Drive was never realised, although schools will be built adjacent to this road.”

    There are currently 3 underpasses under John Gorton Drive.
    The first is in Coombs, adjacent to the primary school.

    The second is at the north end of Coombs, next to Holdens Creek pond. This one has a cyclist/pedestrian path on one side of the creek and a horse route on the other.

    The third underpass is between North Coombs/North Wright and Denman Prospect. next to Coaldrake Ave and next to the new school.

    This third underpass is not yet connected on the eastern side, but a Request For Tender has just been posted for this work to occur later in the year.

    In addition there is another underpass next to the Parks Works Depot, although here the road is called Cotter Rd.

    Also, the old Coppins Crossing Rd will provide underpasses on both sides of the river , as one of your photos show. All the planning documents I have seen for the cycle network in the Molonglo Valley rely on this, but there is some inconsistency about just where they will go.

    It is true that the DA for the bridge shows a possible underpass in the vicinity of Butters Bridge.

    Regards

    John

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    1. The keyword in the sentence is NORTH between Molonglo Stage 3 East and West (Whitlam). In the most recent stage of John Gorton Drive (completed last year), an underpass has been neglected. A school will be built in Whitlam at the intersection between Hazel Hawke Ave and John Gorton Drive. There are no underpasses on the John Gorton Drive between William Hovell Drive and the Molonglo River. This is an oversite as there will be tens of thousands of people living in Molonglo Stage 3 by 2035-40. Kambah was split by a major road barrier hostile to people. Coppins Crossing is a river level, flood-prone crossing that requires a 30 m ascend of up to 10% gradient ie unsuitable. The city should be permeable allowing cyclists and pedestrians to take the SHORTEST route between two points. Car centric road designs often forget this. The underpass on the development application has NOT been planned. The consults have simply noted on the plans that it has been PROPOSED. In other words, if we do not demand it to be included in the construction (detailed) plans we may not get it.

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    2. One further point should be noted here. I refer to your comment.
      “The third underpass is between North Coombs/North Wright and Denman Prospect, next to Coaldrake Ave and next to the new school.”
      There is an underpass here beside the recently open Evelyn Scott school. The path to Coombs has never been completed. The concrete path currently stop on the south side of John Gorton Drive. The bike path along the Molonglo River past Coombs has also not been completed. There are MISSING LINKS at two points discussed in more detail here.
      https://canberra.bike/2021/02/09/john-gordon-drive-underpass-to-combs-coming/

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