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Lane Widening

Lane width has an influence on safety, especially at certain key road locations. Vehicles typically use more of the travel lane on bends than on straight road sections, and head-on crashes can happen on bends when drivers accidentally (or intentionally) ‘cut the corner’.

Widening the lanes on a bend can reduce the risk of head-on crashes by giving drivers more room to get around the bend without crossing into the opposing lane. Similarly, widening turn lanes can improve safety, especially for larger vehicles. Widening traffic lanes on straight sections of multi-lane roads can reduce sideswipe crashes.

On urban arterial roads, lane widths of between 2.75 and 3.75 metres are typically used. Through traffic lanes on rural roads less than 3.0 metres wide tend to have higher crash rates, and a lane width of 3.5 metres is often recommended (except where the presence of cyclists means that wider lanes are needed). It is usually safe for lanes approaching signalised urban intersections to be narrower than high speed through lanes on straight road sections.

Narrower lane widths, whether physical or visual, can be desirable as part of a traffic calming scheme for main roads passing through urban areas or villages.

The Star Rating Demonstrator is a freely available tool with the iRAP online software, ViDA. With the Star Rating Demonstrator, it is possible to explore the impact that this Safer Roads Treatment has on risk.

Treatment Summary


Medium to high

Treatment life

5 years - 10 years



Case Studies