Sunday, 25 July 2021

Hospital Job

In the last few weeks, I have found myself in hospital. Luckily, it wasn't as an in-patient or a visitor, just incidental to some schemes I am working on and it's got me thinking.

Hospitals are funny things because that are not a place as such, they are often more like a large village or a small town. They have buildings with different functions, they have their own street networks and they have transport interchanges. Many also have to deal with significant levels of tidal motor traffic. Some areas are for people who work there, some areas are for people visiting and some areas have people staying long term. They are also a places of joy and misery, birth and death. 

Hospitals also have tentacles which extend and influence the communities around them, depending on where they are located. Some of course remain in urban areas, but many are on the edge of town where urban sites have been consolidated and the land sold. In some cases, they are as difficult to get to as the next town or village. Some hospitals started as a hamlet and have simply evolved to their small town status. Others have been planned, but changing needs have eroded the original vision and they have ended up being a sprawling mess.

Basildon Hospital in Essex. The main entrance is
over 300 metres from the nearest public road and
that public road is a massive roundabout designed
to move traffic around.

I guess some of these things could apply to higher education campuses, business parks, regional shopping centres and the like, but hospitals will always have that little bit more going on which makes them an interesting case study as a land use. The other dimension is that the largest hospitals are often up there as one of a town's largest employers and so the fortunes of that town and its citizens are inextricably tied to it.

City centre hospitals (in theory) should be simple enough to get to by foot, cycle or public transport and precious land reduces the ability of car parking to be provided. Because of building security, however, access is sometimes only easy from one direction with a main entrance. A key "journey end" of walkability is having easy to access (and legible) building entrances - if they are tucked away or require walking around a city block (depending where one walks from), then they are less attractive to the visitor. The same goes for cycling, although at least someone on a cycle can more quickly get round the block!

Queens Hospital, Romford, East London. An entrance point
is just to the left, 200 metres from the main public cycle
parking. The sign post on the left has a "cyclists dismount"
sign on the same sign as directing people to the cycle parking.

Out of town/ sites on the edge of town are a nightmare. They are often away from significant public transport interchanges and this immediately erodes the ease of walking there. Cycling access will of course depend on the quality of local cycling infrastructure which as we know will be highly variable. More than that, assuming someone makes it to the site perimeter, it's often a long walk to the reception and cycling is rarely provided for.

In terms of planning for walking and cycling for a new or existing site comes down to giving people direct options. Walking can of include getting from any site bus stops to the entrance and cycling becomes walking as soon as cycle is parked. Walking also becomes the mode of choice where people drive to the site and have to get into the building. Giving people direct options will be a combination of the following;
  • Develop a direct walking and cycling network from multiple points on the site boundary. Give people the option to arrive at plenty of points on the perimeter;
  • In this network, make sure there is an orbital route (with walking and cycling in their own spaces if possible). This helps people get around the site to get the right building/ building access point, plus the hospital estate actually creates part of a much wider traffic-free route;
  • Unless there are small blocks, provide multiple access points to the estate buildings. If someone has to walk for 10 minutes within the building that's an unseen barrier;
  • Provide secure cycle parking right by every entrance, both public and staff. Really make it easy to get right to the entrance nearest the department that people need to access. For staff this will mean the provision of lots of showers/ changing points rather than one central one that they have to schlep to
  • Get bus stops as close to the building as possible. Where set some distance away, then provide a wide, direct and legible walking route so people can see the main entrance from the bus stops and the bus stops can be seen from the main entrance. Real time bus information in the entrance area also means people can stay in the warm.
  • Place general car parking on the perimeter of the site - if people are going to be driving, then they will need to walk the last part of their journey, but it will be on the direct walking network provided. Blue badge parking should be placed close to entrances, but access to it should not be prioritised over walking and cycling routes.
  • Passenger transport and emergency vehicle access points should be provided at appropriate locations near the building, but care should be taken to make sure that maneuvering of ambulances and mini-buses should't conflict with walking and cycling routes.
  • Drop off/ pick up points can be close to building entrances, but access loops should not conflict with walking and cycling routes.
  • Develop a system of wayfinding which integrates with the same approach outside of the site. Of course, this relies of the site being plugged into a decent highway network, but getting the hospital right will help make the case for external investment.
Now, there will be all sorts of other soft measures such as travel planning for staff, but getting the infrastructure right will future-proof the changing needs of the site in future and soft measures will be about signposting how people can travel rather than encouraging them.

Westminster Bridge, London. A cycle track passing
Guy's & St. Thomas' Hospital (behind the trees). Cycle parking
is under the main building, but to get there one has to mix
with traffic in the undercroft service area.

Hospitals by their nature will have people visiting who cannot walk and cycle and that is fine, but many people (including many staff) can and we should be giving people real choices. If we got this right, then we'd see pregnant people cycling to antenatal appointments, people walking to get their blood tests, people cycling for checkups and staff being able to choose an active mode to help with their own heath and stress. People who have to drive could do so and they may stand more of a chance of getting a parking space.

Like anything in life, changing the transport footprint of a hospital takes effort and resources. It also requires thinking both within and beyond the site boundary to make sure everything is integrated. It is increasingly rare for people to go through their entire lives without visiting a hospital and so we really should be making this as easy and stress free as possible. For my mind, walking and cycling should be a key part of this. 

Have a look around your local hospital and I bet in most cases, you'll find another car-dominated mess which is reflective of our wider planning environment. You'll find archaic rituals for staff wanting to get car parking permits, cycle parking will be an add-on and walking routes will be confusing across sprawling sites. In many cases, direct walking and cycling routes will be through service yards or will have buildings blocking the obvious way through. As ever, I'd be interested in your views and experiences.

Sunday, 18 July 2021

Speed Differential

We get the people we design for and when it comes to people driving, the design of the road ahead will be a big influence in how fast they will choose to drive, regardless (to some extent) of the posted speed limit.

Let's start at the "fast end" with a quick look at the Design Manual for Roads & Bridges (DMRB). For those who don't know, the DMRB is a design standard for trunk road and motorway schemes for Highways England and devolved national administration projects. Many local authorities use it for trunk road-style schemes, but the standard isn't written for them, so it's merely guidance (which explains the cherry-picking going on in lots of cases).

DMRB is concerned with the safe maximisation of traffic speed and capacity. Trunk roads and motorways are there to carry long distance traffic and so designs which don't accord with those principles will compromise safety and capacity plus speed to some extent. For example, there are forward visibility requirements for curves so that it is safe to drive through them at the National speed limit. Compromises will be around width of the alignment, geometric matters (curves and hills) and other more detailed considerations.

Motorways are design for high speeds and capacities.

If there are compromises to the point where those speeds cannot be safely maintained, then that's often where speed limits come into force, although on a network where people are used to driving at speed, asking them to change that behaviour is challenging and so average speed cameras are becoming more common.

In the absence of too many compromises, motorways and trunk roads are designed for 120km/h speeds (75mph) for dual carriageways and 100km/h (62mph) for single carriageways. There are always people saying that car technology improvements since the original design parameters were developed means that we should be raising the speed limit. That's true to a certain extent, but things such as physics and human behaviour don't change. 

The design speed takes into account that not all vehicles and not all people are in perfect condition and so while a Formula 1 driver on a perfectly surfaced motorway without other traffic will be able to go far faster than 120km/h, the same driver in a fully laden works van on a surface due for renewal is a different matter. There is a balance between risk and safety being employed.

A current example of how the speed limit and the compromises pan out is the A465 Heads of the Valleys scheme in South Wales which has seen the section dualled. There will be a 50mph speed limit in place which is predictably controversial, especially as this is the same as the old one. If you look at a map of the scheme between Brynmawr and Gilwern, you'll see that the horizontal alignment is full of curves, the vertical alignment differs between the two carriageways and there are constraints at slip roads. It's not another front in the war on the motorist, it's the designers having to work within the geologically and geographically challenging Brecon Beacons!

As you move into more urban areas, the motorways may start to fizzle out for the the most part, but there are trunk roads. Many are a legacy of schemes built decades ago. The standards back then will have been a little different, but not overly so and as they wind through the communities cleared out the of the way, you'll often see tighter curves and short slip roads. Maybe speed limits weren't imposed originally, but years of collisions have made them a necessity.

A12 Ilford. This section has frontage activity, crossings
and side streets and so a 40mph speed limit.

If we then look at speed from the other end of the scale, on residential streets, we should be seeing very constrained layouts which physically make it hard to speed. This is a pretty universal concept, but in the UK, it can be found in Manual for Streets

Figure 7.16 (above) shows the relationship between road width and forward visibility with the 85th percentile speed (85% of drivers will "naturally" drive at or below this). It's also something that the Dutch have long since been skilled at in terms of keeping driver speeds low as well as making residential streets access only (Low Traffic Neighbourhoods in the UK zeitgeist). 

A low speed street, Utrecht, The Netherlands.

The biggest challenge for us is those streets which maybe sit between the two extremes, or at the very least are wide and easy to drive at speed, despite the presence of frontages and street activity. It reminds me of this short video - "Conversation With An Engineer" where a "street improvement" isn't actually aimed at the people who live there;

This video has strong parallel to many UK "improvements" where we've made it easier to drive through towns with gyratories, carriageway widening and miles of guardrail because an urban road is stuck with a legacy function for moving long distance motor traffic. These streets become harder to cross, nowhere to cycle and motordom ultimately exerts its dominance. People are then surprised that there is a speed problem, but when you give urban streets a hint of trunk road, that's what you're going to get.

Crucially, as driver speed increases, their ability to perceive what is going on reduces and their field of view decreases as shown in the wonderful diagram above from the Streets Minnesota campaign. On a motorway or trunk road without other things going on, higher speeds are fine, in urban areas they are a killing ground. Above 20mph and people outside of cars rapidly and non-linearly suffer death or serious injury from collisions. Streets engineered for high traffic flow attract speeding and speeding drivers don't see enough of what's going on.

There are lessons in design here. First, is how we deal with transitions from motorways and trunk roads to urban situations (and I'd include villages here) with treatments that reinforce the change in environment. People don't simply change their behaviour after driving in a fast environment, it takes a little time. Second is if we design in layouts and alignments which entice speeding in inappropriate places, it should not be a surprise to see speeding and severe outcomes from collisions. Third is that simply placing a speed limit sign isn't going to solve the issue. While there will be some modification of behaviour, design will always be more powerful in influencing behaviour.

Saturday, 10 July 2021

Got Any Salmon? Sorted.

Should we be building one-way or two-way cycle tracks? Should we be building cycle tracks at all? It's one of those tricky issues which attract lots of opinions, but for which there isn't always a clear answer. But yes, I have Opinions.

My own starting point really comes from two viewpoints which I think are reasonably practical rules of thumb;
  • One-way tracks should be used on streets.
  • Two-way tracks should be used on roads.
OK, there are subtleties between the definitions of roads and streets. In fact, there is also a a prerequisite of how we define the highway network as I think most people could understand a starting point which provides *no* cycle tracks.

The photograph above is an example of the base situation for cycling infrastructure on a street - none. Streets should be motor traffic-free to a point that anyone can use them for cycling in the carriageway. If we can get that right, then we've cracked a significant part of developing a cycle network because many cycle trips will be starting and ending where people live. 

Having people cycling in the carriageway is obviously a cheap solution, but more than that, it does avoid the clutter that cycle tracks can bring to the visual and physical landscape, notwithstanding the fact that cycle tracks and most street clutter is there because of motor traffic. Quiet streets still allow access by motor vehicle for those who need it, but over time, we get all sorts of opportunities to repurpose space for other things.

Francis Road, Waltham Forest. No cycle tracks here,
but low traffic means more space for people.

Getting to that point is obviously a challenge in itself and this is why Low Traffic Neighbourhoods feature so heavily in network planning and design - they are vital. However, we know that some streets, and certainly roads, will be taking too much motor traffic for most people to feel safe mixing with it. So we still need cycle tracks.

The other thing to say is that we might need cycle tracks in places that if the World was sensible, we wouldn't, but until we do tame those places, cycle tracks are important to get people cycling in them. A good example is Kent Street, Birmingham (below). This should be a low traffic street without cycle tracks, but currently, it provides a connection from the city centre to the A38 cycle route.

There's lots of development going on in the city and so eventually these older industrial and commercial streets will become more residential in nature and so access for HGVs for older uses and the redevelopment will cease and the protection should no longer be relevant if the right decisions are taken.

I wish I could remember where I read it, but I am sure I read that around 80% of Dutch streets don't have cycle tracks and if you've ever nosed around the country in person or on Google Streetview, you can see why. In fact in common with the UK, the Dutch have lots of very old city centres within which it would be hard to fit cycle tracks, it's just that the cars have been cleared out making them unneccessary.

The Old City of Utrecht. There's no space for cycle
tracks here, but there's no space for lots of motors,
so it doesn't matter!

OK, at some point we do need cycle tracks, even though I have so far both dismissed their use and called them motoring infrastructure (which they are). One-way or two-way? For most urban applications on connector type roads (which connect local access streets to main roads), I want to see one-way cycle tracks. The main reason for this is around how we treat junctions that are not controlled by traffic signals; notably side streets.

Despite people driving having received training and with the vast majority thinking they are better than average, surely people should be able to cope with people cycling at side roads. Except they can't. This is both a design and a psychological issue whereby drivers entering or existing side roads either aren't expecting someone cycling to be there or they didn't see the person. 

From a driver's point of view, you expect to see
vehicles coming from the right as you reach the junction.

From a driving point of view, emerging from a side road puts you in a position where you will expect drivers coming from your right. If there is an obvious cycle track, then it's easier to expect someone to be cycling there. With two-way cycling, an emergent driver isn't necessarily expecting people cycling from the left. You'll have realised of course that people walking along the footway will come from the left too, but they are not moving at cycling speed which mitigates the issue somewhat.

This always makes me remember a story that fellow designer, Brian Deegan, recounts about his Royal College Street scheme in Camden, London. The (one-way) street used to have a two-way cycle track on it's eastern side and there was a problem with driver vs cyclist collisions at the side streets. Being a one-way street, drivers didn't have to worry about motor traffic from the right at all and so looking right wasn't a priority.

Over the years, the warning information to drivers on the side streets was added to leaving a patchwork of brightly coloured surfacing supported by lots of signage, including flashing amber signals warning drivers of the cycle track. The image below is of Pratt Street in July 2008 looking towards Royal College Street.

Despite the money spent on all of this clutter, the collision problem persisted and eventually, the layout was changed to place one-way cycle tracks on each side of the street using planters and floating car parking. This dealt with the main collision problem (below).

Unfortunately, the planters eventually got wrecked by drivers and have since been replaced with kerbs.

Of course, this approach doesn't design out left and right hook movements by drivers turning in from the main road, but again, cycle traffic will be coming from the "expected" direction. Hills Road, Cambridge (below), has one-way cycle tracks and despite being a main road (A1307), there are plenty of side streets and private accesses which makes one-way cycle tracks an appropriate choice for the local conditions.

The other thing in favour of one-way cycle tracks in urban areas is that for those accessing premises to and from them, they don't have to cross the road to immediately access/ leave the cycle track. However, this also means that regular crossings of the road are needed otherwise people will simply cycle the "wrong" way, affectionately known as "salmoning". 

In the UK, all cycle tracks are two-way in law unless modified by a traffic order and frankly, many highway authorities don't bother making an order because they either don't realise it or they don't know how they will sign it! So "salmoning" is largely a design issue than a legal one in my view.

For people crossing, one-way cycle tracks give more comfort that they are only having to contend with one "traffic" direction which is helpful in tight locations where people cross opportunistically from the cycle track or if they are crossing to access a bus stop (above); there is less going on to have to cope with.

For example, this crossing (above) on Lea Bridge Road in Waltham Forest gives an opportunity for a u-turn by people wanting to easily cross the road from one one-way cycle track to the other on the far side of the road.

Two-way cycle tracks (by design) are better for the very large urban roads or rural situations because opportunistic crossing is going to be much harder and is probably only going to be possible at signal controlled junctions.

The above photograph is Vondellaan in Utrecht which has a section of dual carriageway with a one-way cycle track on the north side and a two-way cycle track on the south side. I don't know the full story, but the layout means that people from the north wishing to head east don't have to cross the road. 

It runs next to the railway and so essentially provides a route for people coming from the north of in the older part of the city where there wasn't space for cycle tracks. To the east, the two-way cycle track enters a large residential area as a direct route away from traffic. The design is a response to the local situation and is more about disentangling the cycling and motoring networks.

Above is a two-way cycle track on Burgemeester de Meesterstraat in Harderwijk. Again, I don't know why a 2-way cycle track was provided, but it is only on one side of the road, so maybe it was a space issue. There is residential development on the eastern and so people have to cross the road to reach it. There is no development on the western side, but there is land ready for building.

The existing residential development seems to have been there some time and the addition of the cycle track is relatively new (2016) when buildings on the western side were demolished, so I think it was probably a result of the space and the phased redevelopment.

In the UK, two-way cycle tracks have been quite popular in recent years. For example the C3 and C6 (below) cycle routes in Central London have large two-way sections which have to some extent operated tidally which is space efficient which has minimised the space taken from general traffic lanes.

They are also easier to thread through signal controlled junctions as can be seen below on C3 on Lower Thames Street at Fish Street Hill where there is a right turn ban on general traffic leaving the main road.

In situations like this, the main road can run on a green signal at the same time as the cycle track which simplifies the operation of the junction. Two-way tracks also require less construction work (in general) than two one-way tracks and where kerbs are paid for by the metre, this can be a small fortune saved.

They are also favourite choices along rivers and seafronts such as Marine Parade, Great Yarmouth (below), because of the general lack of busy side roads which need to be catered for. Of course, access to the attractions on the other side of the street are difficult to get to.

There's also the matter of rapid deployment, an issue which has been in our minds over the last year or so. For a wide street, a two-way cycle track can very easily be deployed, although there still might be works needed at junctions, side streets and kerbside features such as bus stops. Bradford Street in Birmingham (below) was rapidly deployed, but wasn't very good at bus stops (although it is being redesigned).

Where a choice has been taken for urban two-way tracks on one side of the street, the risk at side streets can be mitigated by providing some waiting space for drivers so that they can tackle crossing the cycle track without having to worry about stopping on the main road such as St Georges Road, Lambeth (below) and with some turns being banned.

In rural situations (between settlements), a single two-way cycle track on one side of the road is enough because it's less about capacity and more about utility and connecting villages to towns. In most cases, there will be very few pedestrians and so shared-use paths are appropriate such as on the island of Fanø in Denmark (below).

Of course, these might skirt small settlements where a few people might catch a bus and so some waiting space off the cycle track can be useful as below) near Amsterdam (although wider space with a seat and shelter would be more useful!)

So, is there any official guidance? LTN1/20 - Cycle Infrastructure Design gives some help from Paragraph 6.2.15 onward and it includes a handy table (6.2) summarising the issues and opportunities that two-way cycle tracks present (reproduced below).

So, we need to think about the type of street or road, what's happening in the wider highway network (for general traffic as well and cycling) and there's complexity and cost considerations. Hopefully this discussion will help you to understand and maybe challenge some of the decisions being taken where you are

Saturday, 3 July 2021

The Playing Field Is Not Level

The problem with traffic management is it's predicated on the proposition that one can drive or park where and when one wants unless modified by national law or local traffic order. 

The management of our streets is a fundamentally unlevel playing field which takes significant investment in effort, political capital and public funds to do anything which favours the protection or prioritisation of people walking and cycling.

The need to add the ability for formal control tracked the invention and intensification of the motor car. The first restrictions actually predated cars a bit with the various "locomotive acts" adding restrictions towards the end of the 19th centuary. We were moving from steam-powered remnants of railway offshoots into the age of the internal combustion engine. 

In 1931, speed limits were abolished, but by 1935 speed limits were back with 30mph as the default in built-up areas following a huge increase in death and injury which Sir Leslie Hore-Belisha described as "mass murder".

Car parking is also tracked by legislation. There's a great potted history on the UK Parking website which shows the need for regulation and management always playing catch up with people's behaviour. Many local authorities have taken on parking enforcement powers over the last 20 years, but there are places where the police still enforce (with sporadic quality).

These days, we have a slew of legislation such as the Highways Act 1980, Road Traffic Regulation Act 1984, Road Traffic Act 1988 (and 1991), Roads (Scotland) Act 1984, New Roads and Street Works Act 1991, Traffic Management Act 2004 and so on. The legislation has been developed in response to our changing needs around how roads and streets are managed.

With traffic management, any changes we want to make from the default positions of 30mph speed limits in urban areas, the national speed limit in rural areas and a free for all in terms of car parking requires either national (or devolved administration) changes or local traffic orders. While there has been some tinkering with the national speed limit, Wales pushing ahead with 20mph instead of 30mph for urban areas, pretty much everything is done locally.

When I say locally, I mean it. Street by street, change to the status quo by change to the status quo. At the barest legal minimum there is a requirement to advertise and publicise proposals. Rather bizarrely, freight transport organisations must be consulted with. Although other organisations and groups may be consulted if it is deemed appropriate by the order making authority, the Freight Transport Association and Road Haulage Association get special treatment. Another indictment on how things are skewed if you ask me.

Traffic orders aren't going to change the world on their own. They are part of a process which is required to enable lots of physical changes to become lawful, but the way in which they are framed automatically requires a certain level of administration. From an operational point of view, changing the status quo can be very emotive and elicit lots of objections which by law need to be considered (not necessarily agreed with but considered).

The law is again skewed here because only written objections are required to be considered. This is on the basis that someone might have a compelling and genuine reason to object because the proposal will impact them profoundly, but this is always at risk at getting lost in the noise and heat; in many cases, people with genuine needs won't or can't respond and risk getting missed altogether.

So, how would I change things? It's going to be tough to unpick decades of legislation and design which have got us to this point, but maybe I can offer some ideas, none of which are particularly novel.

Default speed limits
20mph should be the default speed limit for urban areas and 40mph for rural. Any change from that should be on a case by case basis requiring the local authority to provide justification.

Parking in marked bays only
Allowing parking on streets should be by invitation only - in other words, people can park where there are marked bays. If there isn't a marked bay, then you don't get to park there. Loading remains fine in unmarked areas for up to 20 minutes. Loading bans would just require repeater signs. If we really wanted to push it, then parking would be charged for based on the land values.

Footway parking ban
Let's deal with it once and for all. No more parking on the footway. If a local authority wants to take space from a footway, then it should require carriageway widening along with all of the utility costs and public consultation. Oh, and if the remaining footway space is going to be less than the 2 metre minimum width set out in Inclusive Mobility, you're not having it.

Duty to create a network management plan
The Traffic Management Act 2004 sets out the "network management duty" of highway authorities, but it's high level and doesn't really compel detailed thought and analysis of how the network should operate. We also have the Road Traffic Reduction Act 1997 which never really got going and was largely ignored by the ConDem government, although Local Transport Plans and Local Implementation Plans (London) are still around (and the devolved administrations have their own approaches).

I think we need an overhaul of this. Local authorities should have a duty to develop network plans which require every street to be classified in terms of its traffic function with a long term plan to retrofit the network to match the classification. Side streets should lose through traffic functions and main roads should have cycle tracks and crossings by default (some local authorities are already doing this).

Bring back the targets
The ConDem government essentially got rid of casualty reduction targets (although local authorities could still have their own) thus cemented the start of a "lost" decade of dealing with road danger on our roads which hasn't really changed with the current government. Absolute numbers are notoriously volatile and don't properly deal with "risk exposure", but there needs to be targets by which local authorities can be measured.

Whilst we're at it, let's have them for traffic reduction so that the modelers can show the impacts of a different future. Let's have some targets for depaving, the removal of parking spaces and the roll our of decent walking and cycling infrastructure.


This stuff needs leadership. Ideally, the government should be setting the overall direction (it's currently pushing for more traffic, electrically powered or otherwise), but we need regional authorities coordinating their regions and this extends to having step in powers to deal with failing authorities. 

It needs a proper discussion with citizens to explain why we need to change the way we roll out change because the way we do it now will never address the issues we face. It also needs more bravery by local councillors to stand up for change and more help to empower them to be able to challenge their officers who are not always on board.

It does feel like pie in the sky sometimes and so I'd be interested in your views. How can we move more quickly without leaving people behind? How do we counter the folk who really don't want change? How do we support those worried about change, but who might change if the conditions are right?

Friday, 25 June 2021

Fabulous Fendon Road

You wait ages for a post about roundabouts and three come along at once. After looking at the proposals for North Tyneside and the continental roundabout in Islington in recent weeks, have I actually found a Dutch-style roundabout in the UK?

Well, the other week, I took my trusty folding bike to Cambridge to have a look at a scheme I had hoped to visit last year, but lockdown meant I couldn't travel more than locally. 

The scheme is the Fendon Road roundabout which was rebuilt as a UK equivalent of a type of Dutch urban roundabout where walking and cycling is prioritised over traffic. As a reminder, the Dutch guidance looks like this for this type of roundabout (with general and cycle traffic orbiting anti-clockwise);

This is the CROW Design Manual layout. There are quite a few dimensions to think about;
  • R1 (radius to edge of circulatory area) = 12.5m to 20m
  • R2 (radius to outside of central kerbed island) = 6.5m to 15m
  • ra (entry radius) = 12m (with the central kerbed island)
  • rb (exit radius) = 15m (with the central kerbed island)
  • B (circulatory lane width) = 5m to 6m (depending on R1 and R2)
  • b1 (overrun apron) = 1.5m (minimum of 1m)
  • b2 (cycle track width) = 2m to 2.5m
  • b3 (cycle cross approach) = as large as possible
  • L (distance from edge of roundabout to cycle track crossing) = 5m
The various dimensions affecting the carriageway are designed to require the drivers of small to medium-sized motor vehicles to actually slow down and use their steering wheels which means that interactions with people walking and cycling across the arms and other drivers within the junction are controlled. 

If there is collision, then speeds are low and the risk of serious injury is reduced - sustainable safety in action (but it doesn't eliminate safety risks). The overrun apron gives the drivers of larger vehicles a little more space without making it easier for the drivers of smaller vehicles to speed. The absolute key to the design is having one traffic lane in and out on each arm.

The 5m set back of the cycle crossing means there is space for drivers to stop as they leave the roundabout and the crossing is in a location where driver speeds from both sides are low. The landing for the floating zebra crossing gives people walking some space to pause between crossing the cycle track and then the traffic lanes. 

Dimension b3 is worth pointing out because the larger this is, the more time people driving and cycling have to see each other people cyclists cross - it's gives a little more chance for people to react. My thanks to Calum for noticing a nuance which I had missed. Of course, this dimension also makes sure pedestrians get a decent bit of space between the cycle track and carriageway.

You'll notice there isn't a width of the refuges within the crossings specified because these are more about keeping drivers regimented than expecting people walking and cycling to wait - they are given priority after all; but the refuges are rectangular to force lower driver approach speeds. The usual UK approach is to have triangular refuges to make it easier to driver through at speed. It's worth noting that in the UK, that the addition of refuges to zebra and parallel zebra crossings means that they should be treated as two crossings by users.

I'm not going to go into each detail of the Fendon Road scheme, but on the whole, most of the key issues are dealt with in what is actually a pretty challenging site space wise.

The photograph above is the view into the roundabout from the western arm of Queen Edith's Way. On the approach, there is no cycling infrastructure on what is a pretty horrible road to cycle along. To join the layout, one merely moves to the left to join the cycle track. There are no dropped kerbs that would tip a trike user which is great. The four arms of the roundabout are not equally placed around a circle, the junction is skewed so pairs of arms have a small angle between them which makes it really hard to accommodate left turning vehicles.

The general arrangement of the roundabout has a low upstand kerb to the right (as you cycle orbitally clockwise) and a 45° splay kerb to the left (above). The mini-zebra crossings over the cycle track are on low humps with the levels such that there's a gentle slope across the crossing area from footway to carriageway. Some have suggested that drivers should also have to negotiate a humps which I have a little sympathy with, but the levels really work well and the roundabout geometry slows drivers anyway.

The designers have made the zebra crossings for pedestrians nice and wide which helps both with conspicuity and helps smooth the desire lines people take with different routes through the junction (above).

The vehicle entrance and exit points (the 'L' dimension) is 5 metres which meets the requirements for this type of roundabout and the orbital cycle track is properly circular and meets the carriageway nearly at 90°. This means that drivers wishing to turn left off the roundabout have a good view of cycle traffic and people cycling do not have to look behind them (but as a user, you do need to pay attention to what's happening). 

Because the cycle track is circular this does mean that the cycle crossings are not strictly parallel to the zebra crossings and so this doesn't comply with the daft rules on parallel zebra crossings which require a standard 400mm gap. I don't know if Cambridgeshire County Council is applying for a special authorisation for the layout from the Department for Transport (they should for completeness, and DfT should change this rule).

I've reproduced Figure 10.37 from LTN1/20 Cycle Infrastructure Design which does have "properly" parallel zebra crossings, but people just don't flow like that in a compact situation like this. I'd also point out that the figure's dimensions are lost because of the poor quality of the downloadable PDF.

One piece of detail I was a little concerned about was the choice of gully grating. On the one hand, the unit seeks to minimise intrusion into the cycle track and having part of it in the cycle track drains a bit better than an inlet unit which would be within the kerb. The issue is the longitudinal slots which are fairly short, but perhaps just long enough to catch a narrow or small wheel.

The circulatory area of the carriageway is compact to slow drivers down and features a kerbed apron with a stone sett infill. From a maintenance point of view, I do think that this will be a point of future failure because heavy vehicles and setts simply don't mix long term. I think I would have used imprinted asphalt in this situation as it could be formed to give a kerb-like edge and a textured surface to dissuade the drivers of small cars. 

The eastern arm of Queen Edith's Way is similarly poor for cycling beyond the roundabout, but again, there are decent transitions (above). One odd thing about this arm is that there isn't a parallel zebra crossing. There is an existing vehicle access to a house which means there is a cycle track that drivers give way to with a separate zebra crossing a little further out (below).

This is a perfectly legitimate layout, but it's not quite Dutch. But, it it's a practical solution to the problem and remains reasonably consistent with the design principles.

The junction has some really nice planting and as is the UK way, it has sprouted many Belisha beacons (featuring "halo" light up surrounds for maximum conspicuity - above).

The other little thing which made me smile were the bollards with little cycle and turn left traffic signs just to be sure, despite the layout being very legible and obvious to the user. 

The cycle tracks were perhaps a little tight in places, but they are machine-laid and red - something adopted all over Cambridge (and my favourite colour). If I were to be *really* picky, I would love to have seen the footways paved in light grey block paving to soften the the visuals of the scheme and to differentiate from the carriageway, but I can't have it all! 

Here's a short film of me cycling around the roundabout. What you don't see is me concentrating on what drivers are doing, but because the layout is so intuitive, I only need to worry about what's happening immediately near me. It's easy to see drivers leaving the roundabout as I approach the crossing and as I cross I can see what drivers to the left are doing, (reasonable) safe in the knowledge that the geometry is slowing drivers down - you can see the generally good driver behaviour in action and it all just flows.

The designers have worked incredibly hard to get this scheme squeezed in and working for all users - we often hear about "all users", but it's used correctly here. Before I sum up and offer some closing comments, it's worth having a look at this stunning video by Durman Stearn, one of the project's contractors.

You can really see the elegance of the project and how it all fits together from above.

So, is it Dutch? Pretty much and what is more, it shows that behavior can be changed through design. The UK is terrible at designing roundabouts, a subject I keep coming back to. We tend to design them for maximum traffic capacity whereas the Dutch tend to design them for safety and smooth traffic flow (maybe up to 25,000 vehicles a day for this type).

Slowing things down to speed up overall journeys is known across the North Sea as LARGAS which is an acronym (langzamer rijden gaat sneller) translating to mean "drive slower to go faster" (thanks for the translation, Mark Wagenbuur) or in other words, driving more slowly, but more smoothly means you get to your destination in a more reliable time. In the context of this roundabout it also means drivers can see people walking and cycling in good time and by easing off their speed a touch, they barely have to stop too. 

Here's another video from the excellent Ideas with Beers series which looks at the scheme and there's a talk about before this piece the off-street trials which took place in 2013 and which I experienced in October of that year (yes, it took that long between someone testing it and someone building it).

Would I build this type of roundabout in more places? That's a firm "depends". Cambridge was probably the right place for this scheme because of the fact that lots of people cycle in the city and people who drive there should expect people cycling, although the junction doesn't sit within a network of protected cycleways which is a significant disadvantage to a proper shakedown.

Care should always be taken when copying other countries' designs because the rules and design approaches have subtleties. On the one hand, the blogger David Hembrow suggests we should go for designs where cycle traffic gives way and his blog posts on the subject are vital reading for designers and campaigners alike because it is an approach we can easily copy in the UK. On the other hand, many parts of the Netherlands have decided to push on with the version giving cycle traffic priority in all urban situations and the blogger Mark Wagenbuur explores that in his blog post.

Where the cycle priority design has been chosen, this has been because a municipality have designed to give more cycle priority everywhere and to that extent, priority at roundabouts is consistent and something drivers should be able to anticipate. In the UK, we will have to pick the right locations and unless the geometry is controlled as well as the Cambridge example, we will build risky layouts that lull people cycling into a false sense of security.

There is only one team in the UK which has built a Dutch style roundabout and that's the Cambridgeshire team. I hope that in due course we'll get some longer term learning and study information from the scheme and I'd love to be involved in the design of one myself, so long as it is in the right location. I also think we need to build some of the other type because these can be safely rolled out in far more suburban and rural situations.