I’ve just come across a clear example of what I mean when I say that policy-makers and commissioners could be much wiser when it comes to using behavioural insights, and that being systematic about behaviour could lead to much better policy. In a comment in response to a passing mention in a Bicycle Dutch blog on roundabout design, Patrick Lingwood (whom I believe is Walking & Cycling Policy Officer at Bedfordshire CC) gave this very detailed description (below) of how the authority arrived at a specific design.
It’s long, so I’m going to make my response first; I don’t want to lose anyone here, so I’m not asking you to become experts in comparative cycle infrastructure and roundabout design. Before I do, can I just say that we should be grateful to Patrick for posting in such detail; it’s not often we get such a clear explanation of the rationale behind decisions.
Here’s my point: Bedfordshire’s design (effectively endorsed by the DfT) begins with an assumption about meeting demand for motorised traffic at the current level or higher, and of meeting current demand for cycling and walking, only more safely than at present. With this starting point, the resulting design is probably the best obtainable; personally, I’d love it, as I’m very comfortable taking prime position on my bike.
But I’m pretty sure that behaviour-smart policy-making would start with an analysis of current behaviours. A place-shaping local authority would identify the thousands of journeys of less than, say, 5km that pass through this roundabout daily and use a range of insights into the barriers to healthy, sustainable travel by the people who travel by car but are within walking or cycling distance of their destination. With a clear understanding of the behaviours it wants to encourage, the design process would then begin. And insights from behavioural sciences, along with experience elsewhere, would be used to identify how to make the behaviours being encouraged both easy and normal. This would be reflected in the final design, whereas the Bedford plan is unlikely to reframe walking and cycling as anything other than (as at present) low-status. A behaviour-smart approach might seem radical at the moment, but it’s the future, as policy-makers become more exposed to behavioural insights.
Anyway, I’ve had my say – here’s Patrick’s explanation:
“with regards to the Bedford turbo-roundabout, it is easy to misunderstand the impact of a design on the basis of a short article in LTT (Local Transport Today). The overall concept indeed was inspired by the examples in The Netherlands, but the concept has been adapted to the local environment.
First you need to understand the current arrangement in Bedford. It is an English-style roundabout in the middle of a very Victorian town. The roundabout itself is relatively small but has a relatively wide unmarked circulating carriageway where traffic either circulates as single lanes or doubles up depending on flow. Vehicles circulate too fast, entries are too close and it is difficult to predict vehicle paths, so that other vehicles, including cyclists, find it difficult to safely enter the roundabout. There are several circulating vehicle-colliding-with-entry-vehicle collisions as a result.
Most cyclists are also following a different path from most motorised vehicles. So there are conflicts as cyclists move across the different paths of vehicles. And of course there are the typical entry – circulating collisions where vehicles enter the roundabout without noticing the circulating cyclist.
On top of this, there are high pedestrian flows. There are 2500 pedestrian crossing movements of the arms without any assistance apart from the central islands, with several accidents resulting as crossing pedestrians are hit mostly by exiting vehicles.
So with 32 injury accidents, including 8 serious, over 10 years, at a cost to society of nearly £2 million, there was an urgent need to do something. The roundabout lies on an important route to the town centre and station for cyclists with over 500 cyclists a day, but it is also on a key interurban and intra-urban route with 25,000 motorised vehicles a day.
The council’s first choice was single lane compact (Dutch-style) roundabout. This was modelled but was found not to cope with the vehicular capacity, because whereas compact roundabouts can cope with those kinds of flows, the junction flows at this roundabout are not balanced. This is where the turbo-roundabout concept came to our rescue.
Ignoring the type of cycle provision for the moment, the essence of a turbo-roundabout is that it can cope with higher flows than a compact roundabout (up to 35,000 vehicles per day) because of 2 lane entries and 2 lane circulation. Secondly the raised circulating lane dividers prevent straight-lining through the roundabout so reduce vehicular speed entering, circulating and exiting the roundabout, thereby creating a safety benefit. Finally the spiral lane marking through the roundabout reduces the conflict points as vehicles enter, circulate and exit.
Our estimate, based on the radius of curvature of vehicular paths, is that in Bedford this will reduce motorised vehicle speeds from current 25mph to around 10-15mph, approximating much more to cycling speeds. The lower vehicle speeds allow us to put Zebras on every arm which will further change the way motorists use the roundabout, becoming more aware of vulnerable road users, and further reduce entry and exit speeds.
So with motorised vehicles and pedestrians now catered for, that leaves what is the best solution for cyclists. First it should be understood, notwithstanding the Dutch style preponderance of cycle tracks, if vehicle speeds are low enough, it is safer for a cyclist to go round a roundabout in the primary position. Annular cycle tracks create additional conflict points. In primary position on the road, a cyclist is most visible and has least conflict points, especially so in a single lane compact roundabout or turbo-roundabout.
Secondly, you cannot legally create a non-signalised annular cycle track and a pedestrian crossing in the UK context. This is the significance of the TRL work. It is the first stage in seeking a change in Government regulations to allow this. So either pedestrians get priority at a Zebra or cyclists have priority using Give Way markings (not a feasible option in this context).
Thirdly and most importantly, a cycle track is neither the safe nor correct solution for the Bedford roundabout. The four roads that lead to the roundabout have very high flows of pedestrians with adequate footway widths, but certainly not shared path widths. Most cyclists approaching this junction are on-road, using the cycle lanes on the most congested link. Cyclists going through the roundabout in primary position, i.e. taking up the whole lane, will have no more conflict points than in a Dutch-style compact roundabout, and around a third of the conflict points under the existing design. A detailed analysis of the accidents suggests a 75% reduction in serious accidents and 40% reduction in slight accidents for all modes, including cyclists.
So as long as cyclists are happy to take primary position in front of traffic, they will be safer and get through the roundabout faster than in an annular design. The conflict is between perceptual safety and real safety. The big question is whether cyclists will feel safe in primary position in front of slow moving traffic.
This is where personal feelings often cloud professional judgements. An analysis of Bedford data is that there are 2 types of cyclists – “Quick” cyclists happy to share with traffic and “Quiet” cyclists who want to be segregated from traffic as far as possible. The current division of cyclists in Bedford is around 60% Quick cyclists and 40% Quiet cyclists (on the basis of a survey of station cyclists and an analysis of road usage). Currently at this junction, 350 are on-road and 200 off-road (a lot of those are child cyclists).
So for Quiet cyclists we are creating a cycle track which leads to the Zebras. They will be able to go round the roundabout using the Zebras, 2 of which have been widened to maximum of 4m (on the main cycle crossing flows) to create as safe a crossing environment as possible.
In summary, the roundabout should definitely be safer for all users – pedestrians, cyclists and motorised users, than the current layout. Secondly, unlike now, cyclists will have a legal choice, depending on their nature, whether to go through the roundabout on-road or off-road. Hopefully this will create a virtuous circle of happier cyclists, eventually leading to higher cycle usage. We are thankful that the DfT Cyclist Safety Grant has been awarded to allow us to trial this innovative design.”