Upgrades to two South Eastern Freeway interchanges in SA now underway

Major works have commenced on the $150 million upgrade to the Mount Barker and Verdun interchanges, which will deliver easier and safer connections between the South Eastern Freeway and the Adelaide Hills.

The South Eastern Freeway Interchanges Upgrade is jointly funded by the Australian and South Australian Governments, each contributing $120 million and $30 million respectively.

Site preparations are now underway at the two project locations, with night works construction on the South Eastern Freeway at Verdun starting on 22 February and at Mount Barker on 1 March.

About 31,000 vehicles travel along the freeway between Mount Barker and Verdun interchanges each day, with around 46,000 vehicles travelling from Verdun into the city. Meanwhile, approximately 31,200 vehicles travel across the Mount Barker interchange that sees significant traffic congestion and queuing.

Between 2019 and 2023, there were 43 crashes reported on the Mount Barker interchange, and 11 reported crashes at the Verdun interchange during the same period.

Project map (source: SA Department for Infrastructure and Transport)

The Mount Barker interchange upgrade will include:

• A new three lane bridge over the South Eastern 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
• Upgrades to the existing ramps to and from Adelaide to improve safety and capacity
• A new bus priority lane
• A new shared use path
• A new northbound on road bike lane
• Improved accessibility and safety for Adelaide Road service road
• A new eastbound entry ramp towards Mount Barker
• A new westbound exit ramp
• A new single lane roundabout at the Mount Barker Road and Silver Road junction
• Existing Bus Stop 48A on both sides of Mount Barker Road to be consolidated with Bus Stop 49

Building the new bridge will require installing 12 super-T girders, each weighing 85 tonnes. The Mount Barker interchange upgrade will also see an estimated 20,000 tonnes of asphalt laid and 500 metres of new underground pit and pipe drainage installed.

Project map (source: SA Department for Infrastructure and Transport)

The Verdun interchange upgrade will include:

Transforming the Verdun interchange into a full interchange will allow access to and from the South Eastern Freeway in all directions, improving traffic flow and safety while providing a better connection to surrounding towns.

Currently, there is no exit ramp for motorists driving from Mount Barker to Hahndorf at the Verdun interchange as well as no entry ramps for eastbound motorists. This means those travelling between Hahndorf and Mount Barker can’t easily access the freeway.

The new bridge at the Verdun interchange will be built over the westbound Freeway exit underpass will be 13.45 metres in length with a deck width of 7 metres, supported by 26 concrete piles and 12 bridge planks.

The Verdun interchange upgrade will also include more than 20,000 tonnes of asphalt, 86 tonnes of concrete capping beams, over 13,000 tonnes of granular pavement and 2.25 kilometres of new stormwater pipes.

Once completed, the two upgraded interchanges will provide increased capacity to help reduce bottlenecks, driver frustration and the risk of crashes while better accommodating existing and projected growth in the rapidly expanding Mount Barker and Adelaide Hills area.

With better traffic flow, access and response times for emergency vehicles will improve and tourists will have an easier time navigating the interchanges.

The beginning of construction follows extensive community consultation and information sessions about the transport infrastructure investments in the hills, which was attended by almost 150 community members.

The Mount Barker interchange upgrade will be carried out by South Australian company Bardavcol Pty Ltd, while a joint venture between BMD Constructions Pty Ltd and Leed Engineering and Construction Pty Ltd will undertake the Verdun interchange upgrade.

Both projects are expected to support about 260 full-time equivalent jobs annually during the construction period. The two upgraded interchanges are anticipated to open to traffic in late 2027.

These projects build on the $40 million upgrade of the Mount Barker roundabout at the intersection of Adelaide Road, Alexandrina Road, Wellington Road and Flaxley Road that is currently under construction.

Source: Government of South Australia – Department for Infrastructure and Transport (1, 2, 3); Infrastructure Magazine