Putty Road

• Media release:
  
  Mammoth project to improve resilience along key western road corridors.

One sandstone slope around 452 metres long at Colo (about 190 metres north of McDougall Drive) we removed six trees causing root jacking and slope instability, cleaned drainage along the top of the slope, installed steel mesh reinforcement and applied shotcrete.

This work was performed between mid to late August 2023 and will prevent runoff from seeping into the slope, reducing the risk of further failure.

At a second slope around 310 metres long at Colo (about 518 metres west of McDougall Drive) we removed eight trees causing root jacking and slope instability, three shrubs and other vegetation.

We used a large excavator to remove or scale back boulders and loose material, and break boulders into smaller pieces for transporting offsite to a licensed facility/ or approved stockpile

This work was performed between mid to late August 2023 and involved the installation of rock bolts to stabilise the slope.

In early October 2023, repairs began on two slopes on Putty Road about 200 metres south of the Colo River Bridge. We expect to complete this work by late May 2024, weather permitting.

One of these slopes is about 30 metres long and work involves removing trees and vegetation and transporting this material from the site. We will install additional drainage and soil stabilisation anchors, and carry out restoration work. To further improve road safety, we will also reline the existing culverts.

The second of these slopes is over 60 metres long and requires vegetation removal because of root jacking. We will remove large, loose blocks of stone (some up to 12 cubic metres) and install around 40 rock bolts. An estimated 150 square metres of shotcrete will be applied.

Rock bolts provide active reinforcement to joints within a slope

They transfer the load from an unstable exterior to the much stronger interior of the rock mass

This helps to reduce movement of the rock face.

Example of rock bolt installation to stabilise slopes at Mt Tomah and Kurrajong Heights

Shotcrete is a hardwearing material that sometimes provide a better slope stabilisation than soil nails.

Work crews will apply a wet mix of shotcrete to slope faces where this stabilisation method is a better solution.

Premixed cement will be pumped along high-pressure lines and sprayed at high velocity onto the hard surface and/or steel mesh, increasing overall strength of the slope surface.

Shotcreting avoids the need for costly formwork and reduces waste as we can carefully control the application of the concrete.

To ensure motorist safety, we often need to remove trees and other vegetation during slope repairs.

This is to stop the ‘root jacking’, where trees and other vegetation grow into cracks and joints in the road cuttings and cause the slopes to become unstable.



Transport and its contractors are committed to replanting more trees than must be removed and choose native species for our replanting.



Transport and its contractors are committed to minimising and mitigating environmental impacts. This can include:

• identifying clearance limits to minimise native vegetation removal
• holding pre-clearing inspections by ecologists
• replacing and relocating habitat
• using biodiversity offsets to address tree and hollow removal, after the full extent of local impacts have been calculated.

We will deliver the repairs along Putty Road in project zones. Weather and worksite conditions pending, we will operate crews in up to three zones at the same time. Our traffic control will be staggered to avoid inconvenience to road users.

By grouping nearby projects into zones, we can work under one traffic control set up and complete activity specific work e.g. removal of rock and debris, which needs to be carried out by specialist contractors.

Grouping the repairs into project stages is more efficient and will help minimise our impact on the local community and road users.

See map below for more information about our work areas.

Work area staging

Please allow plenty of extra time while we are working and expect delays.

For the latest updates, visit LiveTraffic.com or phone 132 701

• January 2025 - Slope remediation work on Putty Road between Colo Heights and Mellong from 12 January 2025 (PDF, 223.94 KB)

• Mammoth project to improve resilience along key western road corridors
• Work to repair flood damaged sections of Putty Road is progressing (PDF, 479.96 KB)
• Safer journeys for motorists along Putty Road (PDF, 575.09 KB)