The proposed light rail stop on State Circle at Kings Avenue. Image: ACT Government.
A short tunnel under Commonwealth Avenue to State Circle East has been proposed as the solution to the engineering problems posed by this tight bend on the preferred light rail alignment to Woden.
In a project update, Major Projects Canberra also laid out tree planting plans on Commonwealth Avenue, confirming that the median cedars would be removed under the preferred route.
The update provided some of the most detailed plans yet for the Stage 2B leg to Woden as part of its work on compiling the draft Environmental Impact Statement it expects to complete by the end of the year.
For now, the alternative Barton alignment, despite being acknowledged as more complex and costly, remains on the table as a backup if the State Circle issues on the preferred route are insurmountable.
The tunnel, known as a cut and cover, would mean the tracks on the Commonwealth Avenue median would descend on the approach to Parliament, going under Commonwealth Avenue and popping out on the State Circle median.
The project team says this solution should sit quite lightly in the landscape and be simple from a finished product point of view.
However, it will still be quite complex to construct in a way that doesn’t unnecessarily impact the surrounding traffic.
The alignment would then run around State Circle on the median until nearing Adelaide Avenue where it is proposed to cut through the woodlands over Capital Circle and then via a new bridge over State Circle to continue down the median of Adelaide Avenue.
However, the project team is also considering a verge alignment inside State Circle from Sydney Avenue.
It believes that this approach to the State Circle challenge is an appropriate solution to address the traffic, heritage and multiple approvals issues confronting the project.
Also revealed was that the 45-metre long light rail stops on State Circle will have to be curved to maintain the character of the parliamentary area and not turn the “20 cent coin” that is Capital Hill into a 50 cent piece with edges.
The team is conscious that the project needs to win the approval of Parliament, and it only wants to do it once.
An illustration showing the tree planting scheme for Commonwealth Avenue. Photo: ACT Government.
The Commonwealth Avenue Light Rail Master Plan proposes planting a row of pin oaks between the tracks north and south of the lake, flanked by Himalayan cedars and Chinese elms.
The teams say tree aging and disease have eroded the value of the avenue somewhat, and the new planting scheme is designed to restore a stateliness to the corridor.
No trees would be planted on the median between City Hill and Parkes Way to retain the view.
If the Barton alignment got the nod, trees along National Circuit that were also aging and diseased would also need to be removed.
A decision has not yet been made on the plantings for Adelaide Avenue.
The update reiterates that the lake crossing will be a new bridge between the current spans of Commonwealth Avenue Bridge to create a new prioritised corridor that would move up to 2500 people an hour, compared with the current estimate of 1100 an hour per road lane.
This would be an increase in capacity that was not necessarily subject to congestion and delays associated with travelling on the road.
While buses could be given priority around State Circle from Adelaide Avenue, that would require creating a new transit lane.
Major Projects Canberra was looking at completing the draft EIS by the end of this year, followed by an extended period for public exhibition and submissions.
After submissions are assessed and digested, the EIS is expected to be finalised by the middle of 2025 and submitted to the ACT and Commonwealth for approval.
The project team will then move on to detailed design and the planning approvals – parliamentary, ACT and Commonwealth (NCA).
A Works Approval is not expected until at least late 2026 or early 2027.
Some early works that do not need approval could commence before an official construction start.
The project team has divided the Stage 2B route into precincts: the Commonwealth Avenue Precinct from the end of Stage 2A to Parliament; Parliament House Precinct; the Inner South Precinct, which is largely Adelaide Avenue and Yarra Glen; and the Woden Precinct.
This will allow it to identify local issues and should make it easier for people to provide feedback.
Precinct plans showing proposed works, the Light Rail Commonwealth Avenue Masterplan, Commonwealth Avenue Landscape Heritage Advice, Commonwealth Avenue Bridge Heritage Assessment, and the Commonwealth Avenue Landscape Structure Plan will all be available on the YourSay site.
The consultation to inform the draft EIS closes on 30 June.
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