Unsealed Road Renewal Program 2024/2025

Council undertakes condition audits of the road network every three years through an external contractor.

The audit data is the major input into long term modelling and assesses road shape/profile, cracking, drainage issues and age of material to highlight some keys audit items to apply a condition for each road segment based on pavement or surface.

Inspections are proactive or reactive inspections undertaken by Council as per the Road Management Plan and inform maintenance requirements and workload.

Road renewal may consist of:

• Resurfacing – either spray sealing of the road to prolong the life or undertaking an asphalt overlay.
• Rehabilitation – this could be a mill and fill where a set amount of the existing surface and pavement is removed and re-laid with a stronger material or new material to bring the road pavement and surface back to its original standard.
• Reconstruction – full reconstruction of a road which involves removing or repurposing the existing road pavement and undertake laying of new pavement layers and surface to provide a new asset. This is the most expensive option in road renewal and is a significant capital investment. This is required when an asset has reached the end of its useful life.

Road maintenance is triggered through proactive or reactive inspections and consists of repairing minor defects before they become significant problems. Works include repairing potholes, cleaning gutters and drains, repairing damaged signs and clearing litter.

A re-sheet is when Council renews a segment of unsealed road by clearing and reforming the table drains, re-shaping the road as required and placing additional new material on the road which is typically 100mm thick.

Traditionally re-sheets were generally re-sheeted with 75-100mm of Gherang gravel (the orange gravel) or crushed rock (blue metal).

Officers have commenced using a hybrid mix in a number of sites that places the two products, layered one on top of the other. Through maintenance grading it combines to provide a better year-round surface.

Spray sealing is the spraying of a thin film of bitumen binder on to a road surface, and then covering it with a layer of aggregate.

The bitumen binder acts as a waterproofing layer and prevents water entering the underlying road structure.

The aggregate protects this layer from damage by vehicle tyres, and together they form a durable, skid resistant and dust free surface.

Spray Seal – Layer of bitumen binder sprayed and then covered with an aggregate (stones/rock varying in size from 7 to 14 mm). This is then repeated to give a two-coat seal. Typical thickness is 10-20mm.

Asphalt – Produced in a plant that heats, dries, and mixes aggregate, bitumen, and sand into a composite. This is then installed across a surface. Typical thickness of the wearing course is 25-40mm.

Spray seal is cheaper than asphalt in the short term and it means that a greater length of road can be sealed. However, it does need to be applied in certain weather conditions for the surface to be effective and most durable, otherwise it may be compromised.

Spray seals are better suited to low volume traffic roads as opposed to higher traffic volumes. In certain instances, a spray seal is not a viable solution due to the volume and type of traffic.

Asphalt surfaces generally have a longer lifespan than spray seal over the life of a road and due to reduced maintenance are generally more cost efficient despite the higher initial cost. The increased life is in part due to the thicker application in comparison to spray seals.