The proposed improvements to the roundabout at the northern end of Lambeth Bridge have some merit. Placing the existing zebra crossings onto raised tables, to reduce speeds and improve priority, is sensible, as is the decision to replace the side hatchings with an extension of the footway, which represents a partial tightening of the geometry of the roundabout.
The improvements also include an implicit recognition that the roundabout is unattractive for many current and potential cyclists.
However we are concerned that the response to that unwillingness of those cyclists to use the roundabout – allowing them to use the pavements around it – is inadequate, and unhelpful.
It will bring those cyclists on the pavement into conflict with pedestrians, particularly on the zebra crossings, which the cyclists are expected to use. These cyclists will also have to leave and re-enter the carriageway at conflict points (and, from the plan, at particularly sharp angles).
Conditions for those cyclists choosing to remain on the carriageway will be worsened slightly too; the build-outs reduce the width of the lanes on entry and exit, increasing the potential for conflict with vehicles. We also note that the roundabout will maintain two lanes on exit, moving swiftly down to one, which again supplies potential for conflict.
Rather than providing two inadequate solutions for two different categories of cyclists, we would strongly suggest providing one treatment that is suitable for all, that allows the roundabout to be negotiated safely and smoothly, without bringing cyclists into conflict with pedestrians. Namely, a Dutch-style roundabout, with a wide segregated track around the perimeter of the roundabout. It could pass across each junction arm, with priority, on the same raised table as the existing zebra crossings. DfT regulations already allow for cycle tracks to have priority on raised tables; the track could be separated from the zebra by the minimum two zig zag gap (strictly by regulations), or placed next to it.
The Dutch Cycling Embassy have recently visited the site, and recommend precisely this treatment. Such a roundabout requires only 40m of space; 60m is available at this location.
The track would require a narrowing of the carriageway on both entry and exit (and around the roundabout) from two lanes down to one. This would naturally have an effect on the capacity of the roundabout for motor vehicles. However, it should be noted that most of the roads on entry and exit are single carriageway almost right up to the roundabout itself, and, further, that providing safe and inviting conditions for cycling reduces motor vehicle volume, by modal shift.
The Mayor has signed up to London Cycling Campaign’s Go Dutch agenda, which demands that all planned developments on roads controlled by Transport for London are completed to Dutch standards. This roundabout represents a golden opportunity to do just that.
The consultation closes today - responses can be made here