Light Rail Stage 2B will require a new bridge across Lake Burley Griffin. Image: ACT Government.
The crucial work of estimating how much Light Rail Stage 2B will cost, which will help decide the project’s final route, is in train, with the ACT Government seeking a consultant to advise it.
But the successful consultant’s calculations will remain secret so as not to impact contract negotiations and future procurement.
Construction of Light Rail Stage 2B is timed to begin once the 2A extension from Alinga Street to Commonwealth Park is completed and up and running in 2028.
It will extend the line from Commonwealth Park across Lake Burley Griffin through the Parliamentary Triangle and down Adelaide Avenue to the new Woden interchange.
The project is the most ambitious and costly of the light rail roll-out, involving new bridges across the Lake and on Adelaide Avenue, 10 km of track, nine new stops and other infrastructure.
It will also include substations and upgrades to the existing Mitchell Depot site to house additional light rail vehicles, staff and storage.
There are two route options through the Parliamentary Triangle still on the table – State Circle east, from Commonwealth Avenue along State Circle to Adelaide Avenue; and National Triangle-Barton, from Commonwealth Avenue along King George Terrace, Macquarie Street, Bligh Street, National Circuit, and Sydney Avenue before connecting with State Circle.
The cost of each route option will be a significant factor in the government’s final decision and the consultant will provide a cost comparison for the government.
The consultant will have to take into account the findings of the draft Environmental Impact Statement (EIS) being developed as part of the approvals process.
The draft EIS submitted last year will be assessed by agencies and placed on public exhibition later this year. A final, revised EIS that includes the chosen route would then be submitted to regulators, with approval expected in 2026.
The project needs to be approved by the Territory Planning Authority, National Capital Authority and both Houses of Parliament.
There are two potential route options through the Parliamentary Triangle. Image: ACT Government
Both routes face challenges that could inflate costs.
In 2023, the government revealed that the initially favoured direct route to State Circle had hit an engineering obstacle where the line transitions from Commonwealth Avenue to State Circle.
Last year, it proposed a short tunnel, known as a cut and cover, as a potential solution. This 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 route through Parkes and Barton has always been considered more complex and costly because of the number of environmental and heritage hurdles.
The so-called dogleg also defeats the idea of the north-south spine and would increase the journey time.
The cost estimates will inform the Business Case. But the public won’t get to see them because they will be considered commercial in confidence, and any release would impact future tenders and contract negotiations. They would also be part of future Cabinet deliberations and decision making.
The tender document says the consultant will provide expert advice on costs, cost planning, budgeting and risk analysis.
The consultant will also act as Infrastructure Canberra’s independent cost estimating adviser for the project and may have to estimate the cost of subsidiary projects as well as early and enabling works.
The tender document says the consultant must use labour and material base rates valid at the actual time of its calculations and adjust material rates if there are any changes.
The consultant will also assess the impact of the project schedule on costs.
Any escalation of costs should only be applied for works forecast for financial years after the agreed base date.
All estimates are to be finalised with a list of assumptions, allowances, exclusions and qualifications.
The tender closes on 22 July.
