Here is the short version of one method for calculating what the width of a cycle lane should be.
Method for calculating width of a cycle lane
- Decide what type of cycle lane you are designing
In this example, the lane on the side of a carriageway which has raised kerbs, and with no parking lane.
2. Decide if cycle traffic will be low or high
Higher cycle traffic flows will need to be wider both to increase capacity and to allow bicycle overtaking. In this example, traffic flow is low.
3. Decide what the width of bicycle and rider is
Writing in terms of Dutch legal provisions, Theo Zeegers (Ref. 1899) says that a ” bicycle (on two wheels ..) may legally have a maximum width of 75 cm”. But he goes on to say that “a three wheeled bicycle can be wider, but not wider than 150 cm” and that “it should be noted that a trailer behind a bicycle on two wheels may be 1 metre wide“. In this example, a 1m width would cover both trailers and some of the path wobble and tilt which bicycle riders show.
4. Calculate the width of a bicycle lane from
- a) the shy distance from the edge of the road
- b) the width of the vehicle
- c) the inter-vehicle distance between bicycle and vehicles in the adjoining traffic lane
- a) = 500mm (see e.g. Ref. 1899, also Ref. 1250 example 15)
- b) = 1000 mm
- c) = 750 mm (see e.g. figure 235 in 1617)
The resulting width of the cycle lane is then 2.25m.
Does a 2.25m cycle lane seem too wide?
The UK’s Cambridge Cycling Campaign has a web page (here) which quotes eight different sources which recommend a cycle lane width of 2m. The footnotes on the page include the comment that:
“It is not acceptable to provide narrow cycle lanes in order to give motor traffic more room or greater priority. As made clear in the Lancashire cycling design standard, narrow cycle lanes increase the level of hazard and intimidation to which cyclists are exposed, and are almost always worse than providing no lane at all”.
The width of 2.25m suggested here for a cycle lane applies to
- An on-road lane next to the edge of a kerbed road
- Where cycle traffic flows are low
- Where the lane is not close to a junction
- Where the lane is not used for bicycle overtaking
- Where the lane is used for one-way bicycle traffic flow
In other circumstances – for example, high cycle traffic flows – the cycle lane width would have to be greater.
The London cycle network – design manual (Ref. 1117) in table 2.2 suggests widths for an advisory cycle lane which range from 0.8m to 1.2m. It sounds like these are far too low to be safe (see for example this blog post and this blog post, both from 2011). If there is not enough road width for a safe cycle lane and traffic flows and / or speeds are too high for a shared bicycle / motorised vehicles traffic lane then the authorities should
- ban bicycles from this road and
- construct a solution for a safe cycling route
1117 – UK, “London cycle network – design manual”, RB Kingston upon Thames; 1998
1250 – USA, “Bicycle compatibility index, a level of service concept, implementation manual”, FHWA 1998
1617 – Germany, Wolf et al, “Strassenplanung”, Werner Verlag 2013
1899 – Netherlands, Theo Veegers, “About bicycle path widths”, CROW 2004