As massive housing developments bring more cars to the Adelaide Hills, there’s a growing need for upgrades. Here’s your guide to the area’s major roadworks for 2025, from Mount Barker to Mount Pleasant.
If you’ve ever muttered “not another roadworks sign” while driving through the Adelaide Hills, you’re not alone. But take a second to consider this: these upgrades aren’t just about fixing potholes, they’re setting the region up for the future.
With large-scale housing developments in Mount Barker and beyond, traffic in the Hills is only going to grow. That’s why the South Australian and Australian governments are investing over half a billion dollars into big road upgrades, ensuring the network can handle the boom with better roads.
To help keep you updated about road projects in the Adelaide Hills, we’ve put together a guide to what’s happening and why it matters.
This is the first in a three-part series covering major road projects across South Australia in 2025 – because if you know what’s coming, you can plan around it.
1. Mount Barker and Verdun: Freeway interchanges get big upgrades
What’s happening?
A $150 million upgrade of the Mount Barker and Verdun Freeway interchanges to handle increased traffic and create better connections between Adelaide Hills and the South Eastern freeway, supporting population growth.
Why?
Mount Barker is one of the fastest-growing areas in SA, and the current South Eastern Freeway is getting more congested.
The existing Mount Barker Interchange will be upgraded to include a new three-lane bridge across the Freeway for northbound traffic, with the existing bridge converted to three lanes of southbound traffic, plus a new shared path for cyclists and pedestrians. It will also include a bigger ramp and new traffic signals to improve safety and reduce congestion.
The existing Verdun Interchange will be upgraded to a full interchange, allowing access to and from the South Eastern Freeway in all directions, making it much easier and safer for drivers to get on and off the Freeway.
When?
Major construction is planned to start in late 2025 with both upgraded interchanges expected to be open to traffic in 2027.
How will this help?
- Improved safety for all road users
- Reduce congestion at peak times
- Improved emergency access
- Better connections for cyclists and pedestrians
All the details: Mount Barker & Verdun Freeway Interchanges
2. Mount Barker: Preparing for the future
What’s happening?
The South Australian Government has committed $40 million to upgrade the roundabout at the intersection of Adelaide Road, Alexandrina Road, Wellington Road, and Flaxley Road in Mount Barker.
Why?
Traffic volumes on these roads and the associated delays are expected to increase significantly as a result of development occurring throughout the Mount Barker urban growth area, particularly during the peak periods.
The upgrade will include a new dual lane roundabout, new signalised pedestrian actuated crossings, shared use paths and road lighting improvements.
When?
Construction is planned to start mid-2025 and be complete in mid-2026.
How will this help?
Residential developments are increasing within Mount Barker and the broader Mount Barker area. The upgrade will cater for the increase in traffic and ensure safe and efficient access for all road users.
A Mount Barker and Adelaide Hills transport study has also been completed, looking at key transport issues impacting growth in this region.
As the population and travel demand increases, pressure on the region’s roads will rise. Better understanding the needs of those travelling to/from and within the region will help future transport planning, decision making and investment priorities to support population growth, economic growth and liveability.
All the details: Mount Barker Roundabout Upgrade and Mount Barker and Adelaide Hills Transport Study
3. South Eastern Freeway Upgrade: A high-tech makeover
What’s happening?
A $350 million upgrade of the South Eastern Freeway, including:
- The Heysen Tunnels Refit and Safety Upgrade to address tunnel elements that were at the end of their service life after over two decades of use. It will also improve safety, along with traffic management and incident response capabilities.
- A managed motorway between Crafers and Glen Osmond. This will be an extension to the managed motorway completed between Stirling and Crafers in 2021, delivering safety improvements such as lane-use signs, incident detection cameras, and moveable median barriers.
Why?
The Freeway is Adelaide’s main link to the Hills (and beyond), but crashes, breakdowns, and congestion are regular issues. The new system will improve response times and keep traffic flowing.
When?
- The Heysen Tunnels refit and safety upgrade is now complete
- The managed motorway works are expected to commence in 2026
All the details: South Eastern Freeway Upgrade
4. Adelaide Hills Productivity and Road Safety Upgrades
If you live in or drive through the Hills regularly, you’ll see changes on multiple key roads, thanks to the $150 million Adelaide Hills Productivity and Road Safety Package.
What’s happening?
- Pavement improvements
- Road widening and easing of tight curves
- Shoulder sealing
- Junction upgrades
- Audio tactile line marking
- Safety barrier installation
- Vegetation management (because fire resilience matters too)
Where?
Upgrades are planned across multiple key roads and junctions, including:
- Intersection of Onkaparinga Valley Road, Junction Road, Nairne Road, Balhannah
- Junction of Junction Road, Jones Road and the rail crossing, Balhannah
- Houghton to Mount Pleasant: North East Road and Torrens Valley Road
- Teringie to Mount Torrens: Lobethal Road between Ashton to Lobethal
- Clarendon to Meadows: Kangarilla Road and Dashwood Gully Road
- Stirling to Strathalbyn: Strathalbyn Road between Aldgate to River Road
When?
Works will continue to roll out over the next three years.
All the details: Adelaide Hills Productivity and Road Safety Package
5. River Road Junction Improvements
What’s happening?
Upgrades to key junctions on River Road to improve safety and access.
Which intersections?
- Mount Barker Road and River Road
- Strathalbyn Road and River Road
- Minor works at Kangaroo Reef, Sawmill Gully and Fairview roads
When?
- Early works start in 2025
- Completion expected by the end of the year
All the details: River Road Junction Improvements
The big picture: Why this all matters
Sure, roadworks can be inconvenient. But think of it this way:
- Less congestion and faster commutes once upgrades are done
- Fewer crashes and safer roads for everyone
- Future-proofing the Hills for growing communities.
These projects are all about making your drive smoother and safer in the long run.
Plan ahead and stay informed
During major works, every effort will be made to minimise impacts, including traffic restrictions, however it is likely that there will be some lane and speed restrictions in place. If you’re commuting (and your work allows it), leave a little earlier or later to dodge peak congestion.
Stay updated on road closures and detours with:
- Traffic SA – Live updates on closures and delays.
- Department for Infrastructure and Transport – Project details and timelines.
- Google Maps and Waze – Real-time traffic conditions and detour suggestions.
That’s your Adelaide Hills roadwork wrap-up – but stay tuned, because we’ll be covering other major projects across Adelaide and SA in future updates. Next up, Adelaide’s northern suburbs.
In the meantime, plan your route, pack your patience, and remember – better roads are coming.
