Bald Hills Road Interchange
Client:
Bardavcol for the Department of Planning, Transport and Infrastructure
Location:
Mount Barker, SA
Planning roadways for a growing population
The Department of Planning, Transport and Infrastructure (DPTI) and the District Council of Mt Barker undertook a number of studies to identify ways to support population growth in the area over the coming 15 years. The studies highlighted the need for road upgrade projects, including a new freeway interchange at Bald Hills Road, Mt Barker.
Tonkin teamed with Bardavcol to plan and design a more efficient way to enter and exit the freeway at Bald Hills Road and increase driver safety at the junction of Old Princes Highway and Bald Hills Road, which had previously been a known black spot.
Rezoning of agricultural land around Mt Barker for future residential growth and development would place stress on existing infrastructure. Tonkin found innovative ways to cost effectively improve transport capacity to cater for a growing population.
Rezoning of agricultural land around Mt Barker for future residential growth and development would place stress on existing infrastructure. Tonkin found innovative ways to cost effectively improve transport capacity to cater for a growing population.
What we did
The new interchange was designed to improve travel times, increase safety and reduce congestion for commuters through the:
- Design of four new interchange ramps
- Creation of roundabouts on both sides of the freeway to connect the new ramps to Bald Hills Road
- Lowering of Bald Hills Road through the existing Armco underpass structure (beneath the freeway)
- Provision of new intersections for local roads affected by the project
- Design of a new roundabout at the Old Princes Highway intersection.
Our response incorporated a higher geometric standard than achieved in the reference design to improve the entry and exit conditions to the existing underpass structure.
What we achieved
To create the most appropriate, functional and cost effective design, Tonkin developed several innovative solutions during the tender phase that improved elements of the concept designs and generated significant cost savings:
- Carriageway widening that used an existing shoulder footprint to minimise disruption to freeway users and provide a safer work environment during construction
- Retention of the existing community wastewater management systems (CWMS) pump station by relocating a roundabout on the reference design
- Relocation of the proposed cross drain to reduce the need for utility services alteration, with all flows to a single spill basin that also improvement water quality downstream.
Due to the number of stakeholders involved and the difference in their project objectives, there were challenges around obtaining approvals and reviews in a timely manner. The project required increased stakeholder management and open and transparent discussions to ensure all stakeholders were satisfied with the project outcomes.
Within the works area there were several major significant trees. Some were within a creek line and of high heritage value. To retain as many of these high value native trees as possible, Tonkin adjusted the design of the ramp alignment around the trees.
How we made a difference
The new traffic interchange improved access, safety and travel times for tens of thousands of people that use the interchange on a daily basis.
Though the project faced several challenges, Tonkin was able to incorporate a number of innovative measures that ultimately ensured the project objectives were met and the project was successfully delivered on time and under budget.
