Bicycle Network Victoria commissioned a study into the evidence for determining traffic lane widths. The study was undertaken by Sinclair Knight Merz Pty Ltd. Current Australian guidelines recommend traffic lane widths of 3.5m as standard which of course can mean no bicycle lanes or shared paths. This study by Sinclair Knight Merz suggest that lanes below 3.5 metres can operate successfully provided that attention is paid to the local circumstances. Something that Main Roads WA needs to reflect on, e.g., the situation with West Coast Drive.The full report can be downloaded here as a PDF. The summary of the report is reproduced below:
This report investigates the evidence for determining traffic lane widths. Road authorities are increasingly considering the range of road users (pedestrians, cyclists, private motorised vehicles, road based public transport and freight) in allocating available road space. This forms the basis of VicRoads SmartRoads Network Operating Plans1. When road designers and operators consciously assess appropriate lane widths, it can result in a more efficient use of existing road space.
Current Australian guidelines recommend traffic lane widths of 3.5m as standard. This report finds that lanes below 3.5 metres can operate successfully provided that attention is paid to the local circumstances.
Research on the effect of lane width
There is little evidence that urban lane widths affect safety. The few formal studies available often pertain to rural roads or to very wide lanes.
Although it is widely held that narrow lanes reduce speeds there is little substantial evidence either supporting or refuting this view.
Appropriate lane widths
Consideration should be given to the desired function of the road. VicRoads SmartRoads approach to road space allocation provides a good starting point. Road resurfacing and reconstructions provide the opportunity to assess the best operation of the road space.
Reductions in lane width require a careful examination of local factors including:
- Vehicle type and volume
- Lane type
- Situation in adjacent lane
- Cross fall
- Horizontal alignment
- Provision for other modes
Examples of narrow lanes
There are many examples where lane widths much narrower than 3.5m operate satisfactorily – some down to 2.5m. In many cases by narrowing the lanes, the additional space has been used to provide for other road functions.
Existing traffic lanes in Melbourne have commonly been narrowed to:
- Retrofit turning lanes within the same road space to separate vehicles travelling at different speeds and to reduce rear end collisions.
- nstall new bicycle lanes or widen existing bicycle lanes.
- Reduce the distance pedestrians have to cross, sometimes in conjunction with kerb outstands.
- Calm traffic as part of a package of measures to encourage lower speeds and improve safety.
- Provide parking lanes or widen existing parking lanes. Wider parking lanes mean more space for drivers getting into and out of their vehicles. This reduces the risk of an opening car door hitting
another vehicle or a cyclist.