The cycling schemes in Bedford and Southampton – the ‘Turbo’ roundabout, and the Itchen Bridge junction, respectively – have been hitting the headlines recently. A post by SmallTown2K (who has been taking a thorough look at the Southampton scheme) goes some way towards explaining why what has ended up on the ground is so compromised –
In traffic engineering parlance, the junction does not operate satisfactorily in the AM peak. What this means is the junction is over capacity. I have no baseline Arcady (roundabout modelling software) for the roundabout to compare to, but the signals are likely lower in capacity and this indicates liable to cause congestion.
Obviously, traffic will readjust and vehicle congestion isn’t the be all and end all, except, in Southampton, almost everyone drives and angry drivers don’t re-elect people. Further, and perhaps less dramatically, as a highway authority, Southampton CC is bound to a Network Management Duty which means they must secure the “expeditious movement of traffic”, albeit that traffic is defined as all road users. In that vein it should be noted for non-locals that the Itchen Bridge is a key bus corridor and congestion over the bridge would affect all these routes and the large number of people thereupon (which offhand I would guesstimate outnumber cyclists in the order of 10:1).
It is this intersection of ‘keeping the traffic moving’ (conceived in terms of motor traffic) and political unwillingness to do anything that might disrupt ‘traffic’ (again, motor traffic) that has seen the removal of the ASLs from the original plans, the extra length of stacking lanes, and so on. The quality of the junction was sacrificed.
There’s a similar story behind the Bedford ‘Turbo’ roundabout. The council simply didn’t want to do anything that might have reduced the volume of motor traffic on the roundabout, resulting in the bodge that is finally going to see the light of day, with cycling effectively pushed onto shared use pavements, with a roundabout design that has the stated intention (whether it will succeed or not is another matter) of increasing motor traffic capacity.
The problem is that cycling is, as always, seen as something ‘extra’ to be accommodated around existing motor traffic, rather than a way of reducing congestion on the network as a whole. In a post yesterday Herbert Tiemens, of the Dutch Cycling Embassy, commented that
congestion easily evaporates with only a low percentage changing cars for bicycles
But we don’t seem to appreciate this in the UK – perhaps because we can’t get our heads around the fact that ‘ordinary’ people could actually switch from their cars to cycling, for short trips, if the conditions were more acceptable.
The truth is that designing junctions properly for cycling hugely increase the capacity of these junctions in terms of the movement of people, even if capacity for motor traffic is reduced.
I dug out an old video of mine, shot in Groningen in 2011, just to demonstrate how efficient junctions can actually be.
This is the north-west corner of Vismarkt, right in the centre of the city, at about 5:30pm.
The video is only 3 minutes long, but I managed to count around 350 people passing through this junction in just that time – almost certainly an underestimate, because the video doesn’t capture people crossing on the arm to the right. This is a rate of 2 people every second, which amounts to at least 7000 movements per hour. It’s hard to say how many people might pass through here over the course of a day, but quite obviously the junction could handle a huge amount of people in a 24 hour period. All this in a small space, with no need for signalisation, or delay. And very little danger!
By comparison, busy junctions like the Bedford ‘Turbo’ roundabout currently handle 25,000 vehicles per day, as does the roundabout at the northern end of Lambeth Bridge – in a much bigger area, with much more delay, and with much greater danger. This junction in Groningen is much, much more efficient at moving people about.
I’m not suggesting that the motor traffic on these roundabouts can, or even should, disappear. The broader point is that shifting people out of their cars and onto bikes would serve to reduce congestion, not increase it – even if that means taking junction capacity away from motoring. But it has to be done properly, so that cycling is a genuine, attractive alternative.