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The Problem
In the Pilbara region of Western Australia, some 1,500km north of Perth, lies Point Samson-Roebourne Road. This sealed road intersects with North West Coastal Highway, connecting the small fishing town of Point Samson at the peninsula’s north end to the larger town of Roebourne 20km to the south. Nearby, the towns of Wickham, Dampier, and Karratha are home to a number of large-scale mining and port activities.

Point Samson-Roebourne Road sees a high volume of heavy vehicle movements, placing considerable demands on the road’s infrastructure. The road’s pavements, structures, and delineation are under constant impact.

The combination of high ambient temperatures throughout the Pilbara, heavy vehicle loads, and thermoplastic materials can lead to extreme pavement temperatures, severely compromising the performance and whole-of-life cost of conventional raised audio tactile line markings.

The Solution
In 2021, OzRumble was approached by Main Roads WA, the major transport agency of the Western Australian government, to initiate a trial of milled rumble strips along Point Samson-Roebourne Road as an alternative to conventional raised audio tactile line marking. The trial and installation were part of a broadscale road safety and maintenance upgrade involving low-cost shoulder widening.

The permanent milled-in profile offered the prospect of a high-performance and long-life audio tactile treatment, using vibration and sound to alert drivers to lane deviation. The rumble strips further offered a treatment that could withstand resurfacing, water, and debris build-up, ensuring continued driver safety.

The trial prescribed milled treatments at different profile depths and spacing, on both asphalt and chip seal pavements. In most cases, the milled treatment was programmed to be installed in either a 10mm or 14mm seal coat prior to a scheduled reseal.

Implementation
OzRumble milled-in rumble strips were installed on asphalt and chip seal shoulders adjacent to the edge line using the Rumbler 6200HD plant and other associated traffic control vehicles. The 200mm wide treatment was trialed at 610mm spacing and was installed at a specified profile depth of 14mm. The subsequent full pavement width overlay was conducted in 2022 and was completed with a 14mm seal.

Outcome
A site assessment conducted in May of 2023 (the equivalent of 18 months and two summers post-installation) showed minimal loss of profile depth. The assessment also indicated no stripping of aggregate from the seal overlay, no cracking or deformity of the milled profile and no fracturing or visible structural damage to the adjoining pavement. There was no accumulation of dirt or debris in the milled profile, and a superior audio tactile effect was observed in both light and heavy vehicles. Furthermore, the rumble strips could accommodate further shoulder seal coats if and when required.

The results of the assessment highlighted the outstanding durability and life expectancy of our milled-in rumble strips. During this trial, we were once again able to successfully demonstrate to Main Roads WA the significant whole-of-life cost advantages of OzRumble audible road treatments, along with our commitment to enhancing road safety.

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Audible treatments for the life of your road