What is a Vehicle Swept Path Assessment?

9 May, 2023
Vehicle swept path assessments are a critical aspect of road design and traffic management. A swept path assessment involves determining the path that a vehicle will take when it passes through a given section of the road network, or along accessways and within car parking areas. This assessment is done to ensure that there is enough space for vehicles to manoeuvre safely without causing damage to other road users or infrastructure.
A swept path assessment takes into account the dimensions of the vehicle, its turning radius, and the surrounding environment. This involves using specialised software such as AutoTrack or AutoTurn to simulate the movement of the vehicle through the road network. The software takes into account the vehicle’s speed, acceleration, and deceleration rates, as well as the surface gradient, lane width, and other road characteristics.

Design Vehicles

There are various types of vehicles, and each has a different swept path. These include passenger cars, buses, commercial vehicles and emergency service vehicles. The size and shape of a vehicle determine its swept path. For example, a truck has a longer wheelbase than a passenger car and requires a wider turning radius. The design vehicle for each site will depend on the nature of the site and regulatory standards. Typical design vehicles for residential sites include B99 and B85 passenger cars which represent the 99th and 85th percentile vehicles in terms of size, respectively.

Vehicle clearances are applied to maintain a margin for error and realistic assessment. Generally, a 300mm clearance is applied to the body of the vehicle in slower speed environments such as car parking areas. Vehicle dimensions, design standards and clearances for car parking areas are provided in the Australian Standards, specifically AS/NZS 2890.1.

Why Are Swept Path Assessments Important?

Swept path assessments are important for several reasons. Firstly, they help to ensure the safety of road users. By identifying potential conflicts between vehicles, pedestrians, and cyclists, road designers can make adjustments to the road layout or traffic management systems to minimise the risk of accidents. For example, a swept path assessment may identify that a roundabout is too small to accommodate a service vehicle without encroaching onto adjacent lanes. In this case, the roundabout may be redesigned to make it wider or to provide mountable kerbs.

Finally, swept path assessments are essential for the efficient use of space. By identifying the amount of space required for vehicle manoeuvring, the site layout and car parking can be optimised to maximise efficiency and usable space.

In conclusion, vehicle swept path assessments are an essential aspect of road design and traffic management. By simulating the movement of vehicles through the road network, designers can identify potential conflicts and make adjustments to improve safety, accommodate larger vehicles, and optimise traffic flow. With the continued evolution of vehicle technology and the growing demand for sustainable transport, swept path assessments will continue to play a critical role in the design and management of our road infrastructure.

Written by Oliver Mihaila - Senior Traffic Engineer

Written by Oliver Mihaila - Senior Traffic Engineer

My role at Amber allows me to work with highly talented people who are driven to make our communities better. I enjoy using data to improve the efficiency and safety of our road networks and transportation systems as it is critically important to ensure people can move around in a more sustainable way as our cities grow.
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Amber Organisation acknowledges the Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

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