Austroads has published a report that proposes a ride quality index of roads for heavy vehicles – a heavy vehicle equivalent of the International Roughness Index (IRI) for cars.
The study investigated the perceived safety and comfort of drivers in a range of vehicles for the purpose of setting Level of Service (LOS) standards, as well as collecting driver seat vibration data to refine a new ride quality index for heavy vehicles.
The value of the road freight task in Australia in relation to Gross Domestic Product (GDP) is the highest of all Organisation for Economic Cooperation and Development (OECD) countries. With Australia’s freight task expected to double over the next 20 years, understanding the interaction between heavy vehicles and the roads they drive on is essential.
The analysis of perceived safety indicated that the minimum design standards for lane and sealed shoulder width for class A, B and C roads confer an appropriate sense of safety for heavy vehicle drivers. The analysis of the subjective comfort data indicates that current maintenance intervention triggers are supported by subjective ratings of ride quality class A, B and C roads intended to serve as freight routes in Victoria.
The vibration data was used to develop a proof-of-concept ride quality index for heavy vehicles that seeks to represent the range of responses experienced by different heavy vehicle configurations to the road profile.
This index, the Fleet Ride Index (FRI), provides the ability to envelope either the entire heavy vehicle fleet, or a customised selection of the fleet for use in areas with differing characteristics of heavy vehicle use (i.e. smaller vehicles in urban areas). It can also produce a single value output similar to IRI and HATI but can be weighted to represent the proportions of each heavy vehicle configuration in the fleet on that particular road type and/or location.
This ability to customise the output should allow road managers a more powerful tool in the management of roads for freight vehicles. However, the collection and analysis of more vibration data would provide a more robust basis for the FRI.