Presuming we all agree that cycle tracks are a good thing along main roads with high (>2000 CPU/day) motor traffic volumes (which I think we do), then we need to decide whether we’d prefer two single direction cycle tracks on each side of the roadway, or one bi-directional cycle track on one side of the roadway.
Visualisation of the Mayor’s cycling vision along Blackfriars Road.
Let’s spend 5 minutes looking at the pros and cons of bi-directional cycleways and at when the Dutch use them. Let’s start with the positives:
- They take up less road-space than two single direction cycleways. You can get away with less width as you don’t need as much curbing or buffer space, plus they can help with tidal flows.
- There’s less to build and maintain, you have half as much to sweep.
- Depending on the roadway in question you could have less junctions to deal with, if you have many turnings on one side of the road, running a bi-directional cycleway on the opposite side so as to save on conflicts might be a good idea.
And the negatives:
- Conflict points with side roads are more dangerous as bicycles will be travelling counter to normal traffic flow. The solution is to buffer the cycleway from the roadway with a cars length (5 metres) to provide a turning refuge, but this adds effective width to the overall required space.
- Can make entry and exit points of the track awkward as bicycles have to cross the roadway to gain access to the cycleway. Running the cycleway for the complete length of a route removes this problem but can cause abnormal stage requirements at the junctions either end.
- Danger of head to head cycle collisions.
So with that all said, which is best?
As always, it depends on context. If we look at what the Dutch say and do we can see that they prefer single direction cycle tracks within urban environments and on distributor roads where conflict with motor and pedestrian traffic is more likely.
The inner ring road in Amsterdam has single direction tracks on each side.
Out of town and on larger through routes where side road turnings are prohibited/minimised, the comfort of bi-directional tracks wins out.
A rural through route with a separate bi-directional cycleway in Drenthe.
If we transfer this to a London context we would come to the conclusion that for example, running a bi-directional track along the Embankment is probably the best solution due to the “completeness” of the route and the lack of side turns on the river side.
Visualisation of the Mayor’s cycling vision of Victoria Embankment.
Whereas the Torrington Place/Tavistock Square cycle route or the Theobalds Road/Clerkenwell Road/Old Street route are probably better suited to single direction cycle tracks due to the number of interaction points with pedestrians and turning motor vehicles.
Images of Clerkenwell Road and Torrington Place courtesy of Google Street View
As always, it’s the right solution for the right situation, there’s no one size fits all solution, you have to look at the bigger picture and look at the road network as a whole, not just at the section or junction in question.