The Molonglo Valley has two arterial road corridors, one running east to west and the other north to south. The North South Arterial has been named John Gorton Drive. The East West Arterial (EWA) has yet to be named and is expected to be completed before 2041. The East West Arterial includes a bridge over the Molonglo River and a new East West Arterial / Tuggeranong Parkway Interchange. The route has been decided and traffic studies are currently underway.
The Molonglo 3 East Planning and Infrastructure Study and the reports written by the consultant WSP is discussed here.
The Molonglo 3 East Planning and Infrastructure Study and the reports written by the consultant RobertsDay is discussed here.
The importance of the intersection connecting Molonglo 3 East with William Hovell Drive and Bindubi Street is discussed here.
The challenges of the topography in Molonglo 3 East and the staging of the Future Urban Area (FUA) is discussed here.
- East West Arterial Route
- Enabling works
- Cost estimate
- Expensive road works
- C10 City to Molonglo Cycleway
- Strategic traffic study findings
East West Arterial Route
Molonglo Valley will essentially end up being two communities by design: Molonglo Valley North and Molonglo Valley South. The Molonglo River and the Molonglo River Reserve will carve the community in two. With just two good bridges in place, and not even a walking and cycling bridge available east of the suburb of Molonglo, it will not be easy for the future 58,000 residents to quickly cross the river. The urban planning radius for pedestrians is 800m and pedestrian accessibility permits path gradients (DDA) of just 5%. Crossing down and up, through the river valley, will be too hard and too far for most.
The East West Arterial may be seen by some residents living in Molonglo South to be an escape route to avoid traffic jams on Cotter Road and to the north along John Gorton Drive, but they will be disappointed. By the time the East West Arterial will be finished, the population of Molonglo Valley will have increased toward 58,000 and new residents will have moved in to Whitlam and Molonglo 3 East. Heavy congestion on the East West Arterial is expected in the morning hours (AM peak) to queue back to the Molonglo 3 East intersection.
The East West Arterial will be built despite doing little for Molonglo South residents, because it is considered far better than doing nothing at all. Making Molonglo work is not one project, but many: John Gorton Drive Bridge, East West Arterial (and bridge), and widening the Tuggeranong parkway north and south, as well as adding a new bridge there, too. Total costs could easily approach $600 million and may make Molonglo Valley liveable, but will not reduce the current congestion.
Remember, you can’t build your way out of congestion!
Doing the achievable
The East West Arterial will run from Tuggeranong Parkway, through Molonglo 3 East, past the Molonglo Group Centre, and continue into Denman Prospect past the shops. Everybody would like to know when it will be open, however, there is a great deal of work that needs to be done first. None of the designs for the bridge or the overpass are finished, and it depends on the completion of many other interdependent projects for Molonglo 3 East, including a possible upgrade of the Tuggeranong Parkway. The East West Arterial Bridge will require environmental studies (EIS), as did the John Gorton Drive Bridge, and that can take years. Having said that, the Molonglo Group centre will come first.
The congestion will remain in the Molonglo Valley after the John Gorton Drive Bridge and the East West Arterial are completed. A strategic traffic study was finalised in 2020 and shows that all roads in and out of the Molonglo Valley will be at capacity by 2041. So far, it appears that living in the Molonglo Valley means living with congestion by design and planning. A more detailed traffic study has gone to tender (38561-DOC-130), and should provide recommendations by 2022. The findings of the current traffic study are included at the end of this article.
A number of major projects (works) are started/planned and will need to be completed before the start of the East West Arterial.
Molonglo 3 East 132kV relocation
The relocation of the 132kV power line was out to tender in 2021. The route follows William Hovell Drive and loops under the Tuggeranong Parkway Bridge over the Molonglo River. The cable is laid along the boundary of the National Arboretum. The project is likely to get underway soon.
A new Tuggeranong Parkway Bridge
If have ridden the CBR Cycle Route C5 to Coombs under the Tuggeranong Parkway Bridge, you would be aware that the bridge has grown massive support columns and braces to strengthen the bridge. Without doubt, the bridge is strong now, but the consultants of this report do not believe that it could be widened for another northbound lane.
The most likely outcome is that another bridge, a twin, will be built beside the existing structure to double capacity and permit a new lane in each direction. This would not come cheap, however, the implications of the construction of the East West Arterial Interchange is that the Tuggeranong Parkway will be required.
(the) arrangement will require a new Tuggeranong Parkway bridge crossing of the Molonglo River. The existing Molonglo river bridge would be reconfigured to accommodate three southbound mainline Parkway lanes. The new bridge would consist of three northbound Parkway lanes.VOLUME 1 – ROUTE OPTIONS ASSESSMENT REPORT, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study, 27 April 2021, 37.
The Tuggeranong Parkway Molonglo River crossing is about two interchanges and not one: the Cotter Road Interchange in the south and the East West Arterial Interchange in the north. The reasoning behind the new bridge is that for interchanges to work effectively, a merging lane need to be provided from the on ramp and this lane must be long enough to give time for the cars to merge at travel speed. It turns out, when the calculations are done, this is merging lane is rather long. The Cotter Interchange is a short distance south of the East West Arterial and interact. We require a continuous third lane both north and south between the two for the worst to be avoided. Conclusion: we build a second bridge.
Even with all these changes, congestion is expected during the AM peak in 2041 from the East West Arterial Tuggeranong Parkway Interchange south to the Cotter Road exit. Traffic will back up into Molonglo 3 East. Cotter Road will remain busy in 2041.
Tuggeranong Parkway is very busy in both peak periods. In 2041 AM the demand for the southbound on-ramp from East West Arterial is very strong, exceeding the capacity of the on-ramp, even with a lane add and auxiliary lane where it meets Tuggeranong Parkway, which causes a queue to propagate along East West Arterial and past the Molonglo 3 East intersection. In the PM, the interchange is clear.VOLUME 1 – ROUTE OPTIONS ASSESSMENT REPORT, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study, 27 April 2021, 58.
Molonglo Valley Interceptor Sewer Odour Control Facility
An upgrade of the sewer pipeline is long planned for the development of Molonglo 3 East.
Upgrades to the existing Molonglo Valley Interceptor Sewer (MVIS) infrastructure on the project site are also under development by the SLA. The project is currently in the design development phase, and designs provided by the SLA team have informed the options development and have varying implications for the East West Arterial options considered.VOLUME 1 – ROUTE OPTIONS ASSESSMENT REPORT, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study, 27 April 2021,37.
The East West Arterial has been estimated to cost $228 million. The estimate includes some things but not everything. Notably, it does not include the C10 City to Molonglo Cycleway, the Tuggeranong Parkway northbound third lane, and the Parkway bridge alterations.
• Site clearanceVOLUME 1 – ROUTE OPTIONS ASSESSMENT REPORT, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study, 27 April 2021, 66.
• Bulk earthworks
• Retaining walls (as applicable)
• Street lighting including conduits
• Stormwater drainage
• Landscaping to verge including drainage
• Landscaping to median strip including drainage
• Incidental works including fencing, gates, and the like
• Road works including subgrade preparation, subbase, and base course
• Pedestrian footpaths
• Segregated one-way cycle way
• Bridge works
• Road furniture such as crash barriers
• Escalation beyond estimate dateVOLUME 1 – ROUTE OPTIONS ASSESSMENT REPORT, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study, 27 April 2021, 67.
• New In-ground services
• Diversion / Relocation of existing services
• Demolition of existing services
• 2 lane cycle highway
• Tuggeranong Parkway northbound third lane
• Alterations to Tuggeranong Parkway to suit new bridge works over Molonglo River
• Cotter Road connector road onto Tuggeranong Parkway
• Signalised intersection for connector road into residential area
• Signalised intersection with the Molonglo 3 East connector road
Expensive road works
The costs of road works add up. Here is a short list of current and coming projects.
Road infrastructure investment 2020-2040 (Molonglo era)
|John Gorton Drive Bridge||$176|
|East West Arterial road and bridge||$228|
|Bindubi Street / William Hovell Drive Interchange||$47|
|William Hovell Drive Duplication||$63|
|Monaroo Highway upgrade||$213|
|Canberra South-West Corridor Upgrade||$100|
A summary of 2041 demographic details for Molonglo Valley provided for the 2041 CSTM traffic model supplied by TCCS.
Demographics of the Molonglo Valley in year 2041
Residents 58,648WSP, Molonglo 3 East Planning and Infrastructure Study Transport Modelling Report, January 2021, 6.
Retail Space 43,000 [m2 GFA]
Education (Enrolments) 5,300
Tertiary Enrolments 0
C10 City to Molonglo Cycleway
The C10 City to Molonglo Feasibility Study (2014) is found here. The realisation of this cycleway is dependent on a bridge crossing over the Molonglo River. At some stage, it was decided that cycleway should follow the East West Arterial. Little was previously known of the East West Arterial. The Molonglo East-West Arterial Road Feasibility Study Options report (27 April 2021) outlines the C10.
Strategic traffic study findings
The findings of the strategic traffic study for the Molonglo Valley were made available in the document, Molonglo East-West Arterial Road Feasibility Study and Molonglo Strategic Traffic Study Volume 1 (27 April 2021), from the tender 38561-DOC-130.
A number of observations were made that were applicable to all scenarios in the AM and PM Peaks (without Western Edge):
– All arterial roads in and out of Molonglo operate over capacity in both peak periods.Technical Note: Strategic Transport Scenarios Modelling, email: Ali Lashkari, SMEC, 19 November 2020, 38. Source: 2021 Molonglo East-West Arterial Road Feasibility Study Options report 27 April 2021.
– William Hovell Drive west of John Gorton Drive has spare capacity, likely because of the congestion further east making it preferable to travel to Civic via Belconnen Way instead.
– William Hovell Drive, east of John Gorton Drive, and Parkes Way generally operate at or over capacity.
– Belconnen Way and Barry Drive, between Kingsford Smith Drive and Clunies Ross Street operate at or over capacity.
– Tuggeranong Parkway generally operates close to capacity in both directions.
– Much of John Gorton Drive and Bindubi Street Extension operate at or above capacity.
– East-West Arterial operates with some spare capacity between the town centre and Molonglo 3 Distributor road and above capacity around the Tuggeranong Parkway interchange.
– Construction of the East-West Arterial reduces traffic on nearly all roads in Molonglo, William Hovell Drive (between Coulter Drive and Bindubi Street), Bindubi Street and Belconnen Way. Traffic increases on Tuggeranong Parkway, William Hovell Drive (west of Coulter Drive), Gungahlin Drive, Parkes Way and Cotter Road (east of Tuggeranong Parkway). Traffic also decreases on a number of local roads in Hawker, Weetangera, Macquarie, Cook and Aranda, indicating better arterial capacity and less rat-running.