From Mount Barker to Verdun and backroads in between, here’s what’s changing across the Hills – and when.
If you live in Mount Barker or spend a lot of time driving through the Adelaide Hills, chances are some of your usual routes look a bit different right now.
From major Freeway interchanges to town-centre roundabouts and winding Hills roads, a stack of big road projects are either underway or about to ramp up across the region.
Some works are already well advanced, others are just getting started – but together, they’re set to change how people move around the Hills in 2026.
Here’s your guide to what’s happening where – and what it means for your daily drive.
This is the first in a three-part series covering major road projects across South Australia in 2026 – because if you know what’s coming, you can plan around it.
1. Mount Barker: Future-proofing a major intersection
Mount Barker’s been booming – and it’s putting pressure on its key intersections.
One of the biggest upgrades is happening at the Adelaide Road roundabout, which around 31,000 vehicles pass through every day.
What’s happening?
The $40 million project (fully funded by the state government) is turning the intersection of Adelaide Road, Alexandrina Road, Wellington Road and Flaxley Road into a new dual-lane roundabout.
The upgrade includes:
- Signalised pedestrian crossings on Adelaide Road and Flaxley Road
- A relocated crossing on Wellington Road
- More traffic lanes and shared-use paths
- Better lighting and visibility
Community feedback also shaped some key design changes:
- Dedicated right-turn access into Mount Barker High School
- Adjusted slip lane to protect significant trees
- A safer pedestrian link to Alexandrina Road
- Upgrades to the car park at Keith Stephenson Park
When?
- Under construction now
- Completion expected in 2026
How will this help?
- Smoother peak-time traffic
- Safer crossings for students and pedestrians
- Better access to schools, shops and the new hospital
More info and updates here.
2. Upgrading the Mount Barker and Verdun interchanges
The Australian and South Australian governments have committed $150 million (80:20) to upgrade the Mount Barker and Verdun interchanges.
The aim is to improve:
- Connectivity to the South Eastern Freeway
- The capacity of the interchanges in response to existing and projected growth for Mount Barker and the Adelaide Hills area
Mount Barker Interchange: Tackling one of the Hills’ biggest bottlenecks
This is one of the busiest entry points to the Freeway. Between 2019 and 2023, there were 43 crashes here, along with regular bottlenecks.
What’s happening?
- A new three-lane bridge over the Freeway for northbound traffic
- Conversion of the existing bridge to accommodate three lanes of southbound traffic
- A new signalised intersection at Adelaide Road and the freeway exit ramp from Murray Bridge
- Dedicated right-turn lanes and ramp upgrades
- A bus priority lane
- A new shared-use path
- A new northbound on-road bike lane
- Improved accessibility and safety for Adelaide Road service road
When?
- Under construction now
- Open to traffic: late 2027
How will this help?
- Safer, easier access to the Freeway
- Less congestion at peak hour
- Better walking, riding and public transport links
- Faster emergency response
- A road network that matches the region’s growth
More info and updates here.
Verdun Interchange: Safer access to and from the freeway
This upgrade is happening in tandem with Mount Barker’s – and together, they’ll transform how the Hills connects to the South Eastern Freeway.
Right now, the Verdun Interchange doesn’t allow full access. That’s about to change.
What’s happening?
The upgrade includes:
- A new eastbound entry ramp towards Mount Barker
- A new westbound exit ramp
- A roundabout at the Mount Barker Road and Silver Road junction
- A new bridge and lighting
- Consolidated bus stops
When?
- Under construction now
- Open to traffic: late 2027
How will this help?
- Complete access to the Freeway in all directions
- Less local detouring
- Safer, smoother trips for Hills drivers heading north, south or city-bound
More info and updates here.
3. Safety upgrades rolling out across the Hills
It’s not all about big intersections. The $150 million Adelaide Hills Productivity and Road Safety Package is delivering smaller – but important – upgrades to roads across the region.
What’s happening?
It’s a rolling program of works designed to:
- Make rural roads safer
- Improve freight and local access
- Boost fire resilience
The upgrades include:
- Road resurfacing and shoulder sealing
- Widened curves and safer junctions
- Safety barriers and line marking
- Vegetation management
When?
This is a multi-year program. Some upgrades – like those on North East Road and Torrens Valley Road – are already under construction (see more info below). Others, including sites along Kangarilla Road and Lobethal Road, are expected to roll out progressively over the next few years.
More info and updates here.
4. North East Road and Torrens Valley Road: Curve widening and safer passing
This stretch of road has tight curves, narrow shoulders and heavy local traffic. The upgrade is part of the Adelaide Hills Productivity and Road Safety Package.
What’s happening?
The upgrades include:
- A new, more durable road surface
- Widened curves and shoulders
- Motorcycle-friendly safety barriers
- Audio tactile line marking and signage upgrades
When?
- Early works: June 2025
- Construction started: July 2025
- Open to traffic: mid-2026
How will this help?
- Safer overtaking and cyclist passing
- Reduced crash risk
- More confidence on narrow corners
More info and updates here.
5. Balhannah intersections: New roundabout and safety fixes
Two local intersections in Balhannah are being upgraded to improve turning movements and visibility. The upgrades are part of the Adelaide Hills Productivity and Road Safety Package.
Onkaparinga Valley Road / Nairne Road / Junction Road
What’s happening?
- A new single-lane roundabout with a mountable kerb for trucks
- Pedestrian refuges and access ramps
- Better lighting and line marking
When?
- Early works: July 2025
- Construction: September 2025
- Open to traffic: mid-2026
More info and updates here.
Jones Road / Junction Road
What’s happening?
- Lighting and line marking improvements
- Widened shoulders and clearer signage
When?
- Early works: July 2025
- Construction: September 2025
- Open to traffic: mid-2026
More info and updates here.
6. River Road: Junction upgrades wrapping up
If you drive between Hahndorf and Mylor, you’ve likely seen the works along River Road – and most of them are now complete.
What’s happening?
Upgrades have now wrapped up at the junctions of River Road with:
- Mount Barker Road
- Strathalbyn Road
- Kangaroo Reef, Sawmill Gully and Fairview roads
The works delivered:
- Road widening and resurfacing
- Lighting, drainage and signage upgrades
- New pedestrian refuge and pram ramps
- Relocated bus stops to improve safety
When?
- Major construction: July to late 2025
- Finishing works: early 2026
More info and updates here.
Plan ahead and stay informed
During major road works, every effort will be made to minimise impacts, including traffic restrictions, but it’s likely that there will be some lane and speed restrictions in place. If you’re commuting (and your work allows), leave a little earlier or later to dodge peak congestion.
And if you’d rather skip the drive altogether? The expanded bus network from Mount Barker is now running more frequently – and might be your easiest option. Find out more here.
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.
