It is encouraging to see a council willing to attempt new ways (for Britain) of designing cycling into junctions. These plans are probably more ambitious than any other roundabout design seen in Britain so far, in the way that they provide cycle-specific infrastructure, separated both from pedestrians and motor traffic. In particular, we like the way that left turns at these roundabouts are fully protected from motor traffic, and do not require people cycling to give way.
However, while we support the principle behind these designs, we have a number of reservations about the execution, especially regarding the potential risks involved to people cycling. Beyond wishing to avoid seeing people being hurt, we also do not want the prospects for properly separating cycling and motor traffic at major junctions harmed by high profile collisions at a new junction of this type.
Mainly, we have serious concerns about a priority cycle crossing of this particular form (which, notably, is entirely new to Britain, and therefore unfamiliar) being employed across multiple traffic lanes, at such a busy location. In addition, the geometry of these roundabouts appears to do little to slow vehicle speeds, further increasing the risk to people using these crossings.
It should be noted that the Netherlands, which has a reasonably long history of priority crossings at roundabouts, recommends against using multiple lane crossings. The standard Dutch priority (and non-priority) cycle track at roundabouts only crosses one lane on entry, and on exit, to minimise risk.
We appreciate that reducing motor traffic to a single lane on entry and exit may be difficult in terms of maintaining capacity (especially in the context of the reduction in lanes already proposed by these plans), but if this cannot be achieved then we would strongly suggest considering alternative proposals - for instance a signalised junction, with separate cycleways.
The geometry of the cycling infrastructure in these plans is less than ideal, with sharp corners. Not only does this make cycling less comfortable, it also increases the risk at the crossings, as it may not be clear to drivers whether people cycling are intending to cross or not, until the very last moment.
Many of the exit and entry treatments are needlessly complicated, with 'Give Way' markings to rejoin the carriageway, rather than a direct transition into (say) a cycle lane - for instance, Fountain Drive, and Sydenham Hill. Other transitions are not smooth or obvious - e.g. the entry and exit on Westwood Hill. If the cycling infrastructure here is going to be used, it has to make sense and be obvious, rather than something that requires an effort to divert onto.
It is also curious that there is no cycle priority across Old Cople Lane, especially in the context of priority across considerably busier arms of the roundabouts. This is an obvious location where a cycle track should have with priority, along with (for instance) a continuous footway, across the junction mouth.
Finally, we would observe that cycling facilities like these are not much use on their own, in isolation. We would like to see high-quality cycling infrastructure extended along the main roads that meet at these roundabouts, particularly along the A212.