Built across the region's biggest river, the 200-metre-long bridge will be the city's tallest, connecting northern suburbs like Whitlam to the rest of the Molonglo Valley.

Jointly funded by the federal and ACT governments, the $230 million project also includes 1.7 kilometres of new arterial roads, two new intersections, off-road shared paths and a pedestrian underpass.

It comes as the ACT government seeks to make Molonglo into a town centre.

Transport Minister Chris Steel said the project will help connect a growing population to retail and other services in the new town centre.

"Together these projects are building these suburbs Molonglo with the infrastructure that they need to be really well connected in with services," he said.

The district is expected to be home to more than 70,000 people by 2050.

Asked why construction on the bridge didn't start sooner, Mr Steel said the project was progressing as planned.

"We always knew that with the current population of just over sort of 12,000 or 13,000 people that there would be a need to have the bridge in place by around 2025 to cater for the growing northern suburbs and make sure that they're connected in with the new town centre," he said.

He added that the Suburban Land Agency has also launched a development application for a further section of work on John Gordon drive south of this project, further boosting connections to the planned new town center.

The new bridge will supersede the the low-lying Coppins Crossing, which has been closed down on a number of occasions due to flash flooding.

City Services Minister Tara Cheyne said the project will make roads safer and more reliable for those driving through Coppins Crossing to Woden and West Belconnen.

She said realignment works on Coppins Crossing were already taking place while work on the bulk of the bridge is due to begin towards the end of the year.

"It will be city building infrastructure," she said.

"The Molonglo town centre is going to be a destination in its own right.

"So this is not just going to be about an arterial road or a corridor for transport but also about connecting suburbs, connecting town centres to each other and supporting the growing communities that we're seeing here."

Ms Cheyne said the government will work with the contractor to ensure Coppins Crossing remains open as much as possible while the bridge is being built.

The government said the new road network will also be able to support a future light rail connection.

Around 560 jobs will be created in the design and construction phase.

Federal Infrastructure Minister Catherine King said the project will provide a major economic stimulus to the Canberra region.

"Projects like this are important to not only keep Canberrans employed and businesses running, but also to provide the Canberra community with better infrastructure and safer roads long into the future," she said.

The project received a funding boost after the federal government overhauled its infrastructure project plans.

The bridge is expected to be open by December 2025.