Ison Road Rail Overpass

Tonkin + Taylor was engaged by Decmil as the lead geotechnical and pavement designer for the Ison Road Rail Overpass—an infrastructure initiative delivered by Major Road Projects Victoria (MRPV). This transformative project introduces a new road and two-span bridge across the Melbourne–Geelong rail line, improving accessibility between neighbourhoods and connecting local communities to the wider road network.

Tonkin + Taylor provided end-to-end geotechnical and pavement support, working closely with the delivery team to manage ground conditions and constructability risks in a live rail environment. Our contributions included:

• Ground Improvement Design: Developed a bespoke solution to support high embankments over compressible soils. The design accounted for rail corridor constraints and achieved strict settlement performance criteria.

• Bridge Abutment Innovation: Designed a composite bridge abutment system combining abutment walls, reinforced soil structure (RSS) walls, and L-shape walls—allowing all elements to function together efficiently. This innovation delivered significant cost savings and was validated by performance monitoring.

• Underground Utility Protection: Designed a scheme to safeguard underground assets during major fill placement, minimising potential disruption and risk.

The Ison Road Overpass is set to become a key transport corridor for Melbourne’s west, reducing congestion and improving travel reliability. Our engineering solutions contributed to construction efficiency, improved long-term performance, and minimised ground-related risk.