TfL Junction Review: Lambeth Bridge northern roundabout

 

Hi all,

I've just received an e-mail from TfL regarding proposed 'improvements' to the roundabout at the north end of Lambeth Bridge.

My initial thoughts: I am underwhelmed.

Did LCC make any contribution to the design process?

What does everyone else think? Consultation closes 26 October 2012.

You can find the consultation here: https://consultations.tfl.gov.uk/streets/betterjunctions-lambethbridgenorth

Kind regards,

Martin.

 

This post was edited by insouciant at 06:20pm 20 Nov 2012.

Replies

so you're supposed to vere off the roundabout, barge through the people on the pavement, and then rejoin a stream of fast-moving motor vehicles

no, this most certainly wasn't our idea

We've been asking TfL to look at Dutch-style solutions, which this most certainly isn't

We've been arguing against this kind of two-tier provision, where 'timid' people cycle on the pavement while the 'brave' mix it with the fast-moving traffic

The Dutch would choose a solution that's safe, quick and convenient for all people in cars, on bikes and on foot

As its using pedestrian crossings then the cyclists would have to dismount unless simply turning left.

 

Each exit from the roundabout has 2 lanes but the roads leading away are single carriageway roads. There is no need for more than one exit lane; making the exit narrower would create space for better cycle facilities.

Anoopshah, I think the reason that each exit from the roundabout has been designed as two lanes is to give greater traffic capacity through the zebra on those exits. I think it is to allow two lanes of traffic to queue prior to the zebra crossings on those exits. Once past the zebra crossings and flowing freely, the general traffic can merge into just one lane. I make no comment on whether this element of the design is good, bad or indifferent.

I appreciate that the design doesn't accord with roundabout designs I have seen and enjoyed using in the Netherlands. But it is an interesting design. There are relatively few roundabouts in the UK with zebra crossings on all arms, and the design takes advantage of this rare situation by allowing cyclists to use those zebra crossings to cross the arms in a way that gives cyclists priority over general traffic. This priority over general traffic is the key feature that I enjoyed about roundabouts in the Netherlands. So although it hasn't been provided in the way we might have wanted, I do find it an interesting design and I do like it. [Edit: I've subsequently discovered that the regulations for zebra crossings in the UK do not give cyclists priority over motor vehicles. This creates a major issue: the proposals invite cyclists onto the zebra crossings, but place cyclists at fault if they're hit and injured by a motor vehicle].

But I don't like the bit on Millbank adjacent to Thames House, where northbound cyclists approaching the junction would have to cycle through the 'give way' line of the zebra crossing in order to get onto the shared use footway. That bit definitely needs fixing.

This post was edited by dominicfee at 12:24pm 20 Nov 2012.

I have done a quick "street view" and just a short way back from each arm of the roundabout, it is a single lane.

The 2-lane in and out is trying to maintain the existing capacity of the roundabout, but in terms of through-put to the junction, it really is a small element which is actually wiped out by the prescence of 4 zebras (which are very difficult to model). The only issue would be with one arm backing up ont the roundabout, all traffic would have to stop, but as this is in Central London, I am not sure this area runs that freely in the peak anyway.

Having the 2 lanes on the roundabout itself allow traffic heading north-south or east-west to "take the racing line" under free=flow conditions and so create a safety risk for all other users (including other motorists).

2-lane approaches to zebra crossings can also be dangerous for pedestrians if one lane is slow/ stationary and one is clear as pedestrians are masked by the slower lane (I know this is an existing layout).

From what I can work out, the proposal is simply 4 x speed tables (which is good from a speed-control perspective) and the hatched area kerbed. I know they are also suggesting shared cycle-tracks as well, but this is a cop out given so much space. TfL claim that it is lawful to cycle on zebras (because it is the carriageway and cyclists can use the carriageway), but cyclists have no priority over traffic when crossing (in the same way as pedestrians do).

A radical solution would be to ditch the 2-lane approaches and use raised and segregated cycle tracks which can be given priority over traffic where they cross - it would be very unusual on such a busy route, but it is legally possible and with a blue CS track it would be pretty clear and if cycle numbers are relatively high, it should make sense.

The loss of the traffic lane would then allow a compact roundabout to be provided which would operate more slowly, but more predictably for all.

I really don't think we should be designing for worse-case peak traffic flow any more, it hasn't worked and left us with historic layouts like this.

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