Five Go Mad In Dorset: Part 1 - EV/AV

Thankfully, we've been able to get away for a break this summer. As had become the family tradition before Covid hit, we went camping, although because of Covid (and a touch of Brexit) it was in the UK - Dorset and East Devon to be precise.

Two days before we were due to load our kit into our aging (2007) Vauxhall Zafira, we suffered an electronics failure which left us stranded for hours just off the A12 in Essex waiting to be recovered. I've been driving since 1997 and this is the third breakdown I have had, which isn't too bad I guess and one of those was a distracted driver wiping me out on a mini-roundabout!

Being picked up at 4am from an isolated bus stop

after hours of waiting wasn't much fun.

For some reason the roads gods weren't on our side that day, despite the car not doing many annual miles and it being kept serviced. Sometimes the cleverer part of the technology simply fails. We were a little stuck, but our local vehicle hire centre sorted us out with a car. As it turned out, we ended up with an "upgrade" on what we had actually booked which meant another interesting bit of transport life experience.

The hire car. With #TheDoodle for scale.

We had ordered a Nissan Qashqai with our variables being cost and boot space - our Zafira can carry our family of five, our large tent, a table, chairs, boxes of food and utensils; and clothes; we have managed nearly three week stints and hundreds of miles across mainland Europe like this in recent years.

As it turned out, we had been given a Vauxhall Grandland X Hybrid 4 (with an automatic gearbox with *8* gears and 4 wheel drive for some reason). My knowledge of makes and models of cars is pretty much stuck in the period before the mid 2000s and to be honest, most cars look similar these days. The first thing to note is this is marketed as a "sports utility vehicle" and compared with the Zafira's carrying capacity, there wasn't very much utility given what we had to ditch in order to fit the tent into the boot!

In terms of "sports", I assume this refers to the insanity of a 146mph top speed and 0-60mph in 6 seconds, the latter because the vehicle is a hybrid with electric drive which adds to the power when one plants one's right foot. Anyway, this isn't a car review as such, but some of the more industry standard features were quite interesting to experience.

The car plugged in for some additional range.

First is the fact it is a plug in hybrid. According to a review I have read, this is more about people using it for daily commutes and short trips using the electric mode which carries one for around 30 miles. This is aimed at people who have somewhere to charge the vehicle at home (and maybe at work). Given that 61% of trips are by car and the average car trip time is 22 minutes (2019), many people using plug in hybrids will barely need to use petrol (in the case of this car, the hybrid range is about 400 miles).

This alone is interesting because so long as people have somewhere to charge (whether plug in hybrid or pure electric), as time goes on, less fuel from the forecourt will be needed and so the whole issue of vehicle emissions duty and fuel duty will lead to a collapse in revenues to the Treasury. This either means road pricing or everyone paying to subsidise driving more than we do today.

The charging experience was also interesting. In Dorset, some council-owned car parks had chargers run by Mer which needed an app to access them with a debit or credit card for the other kind of charging and once we were set up we could use them everywhere. Unfortunately, in some car parks, the chargers were not compatible because like mobile phones, we don't have one type of system. A couple of people on Twitter tried to explain the ins and outs to me, but nominally it's extra faff.

At a service station, this charger had a different plug

system for each parking space.

In Devon, we didn't come across any chargers, but in the motorway services, it was of course a different supplier (Ecotricity) and another app to connect, although apparently this is gradually changing to a tap payment system with the network having been taken over by Gridserve. In the services, there were only four Ecotricity branded charging spots, whereas Tesla were flooding the marking and had installed a dozen (below).

As someone who hadn't needed to work out who does what before, this all does rather feel a bit like the Wild West and already way more complicated than pulling into a petrol station and chugging fossil fuel directly into the tank. At least in the car we had, we carried a charging cable which was stored in a tray in the floor of the boot which is pretty impractical when you are carrying more than a bag of shopping (below). Amusingly, we carried the cable in the passenger foot well on the way home, but the service station charger had a cable attached!

In terms of cost, electrical charging is way cheaper than petrol; even with a very fuel efficient hybrid engine, the public car park charging was less than half the cost per mile than petrol which has to be quite attractive to people in terms of running costs. If you can charge from home, it is of course even cheaper.

Away from the hybrid and charging technology, the car had cruise control, collision avoidance and lane correction technology (which are all pretty standard apparently). In other words, I could set the maximum cruising speed on the motorway and the car would run at that speed. If it detected a vehicle in front (pulling in or slowing down), then the car would also slow down. In fact, the car could bring itself to a complete stop. The lane correction feature basically means that if one drifts too close to a lane line, centre line or edge of carriageway road marking, the car would gently take control and steer back into the centre of the lane.

The cruise control and collision avoidance technology was interesting. Where there were few junctions, letting the car decide these things meant that fuel efficiency was improved as the speed was constantly adjusted for the traffic conditions. At least with this car, you could see what was happening in the left hand circular display with the needle moving between charging (generating electricity through braking or maintaining speed down a hill) and an "eco" range of engine revs (below).

Personally, I thought the car was leaving braking too late, not because it wasn't going to stop in time, but that braking was later than I was taught - I usually brake for me and the person behind who isn't paying attention.

The lane correction technology was a bit disconcerting. When I overtake, I don't always indicate when pulling back in, especially if I am some distance ahead of the vehicle I have overtaken. I also tend to move over gently over some distance and this meant the car did sometimes try to move me to the right when I was drifting back to the left when changing lanes. Perhaps I should have used the indicators more which interrupted the feature! I had to turn it off on some roads because it just became annoying.

These sensors are (I think) at Level 2 of 5 of vehicle autonomy, where the vehicle can deal with multiple functions, but where the driver remains in charge. For someone who learned to drive in a car without power steering and generally owning cars several years behind the current state of the art, I found the experience both easy and disconcerting. At least personally, I am not sure that I will ever be happy with a car taking over the driving task for me. That's not because the technology is untrustworthy per se, but because for many years to come there still will be plenty of humans making decisions in what is a very chaotic and variable-rich environment. In fact, the variable of people outside of vehicles isn't something I want to see removed!

Driving in town (and our campsites) at low speeds, the electric mode often kicked in and it was notable that people outside of the car simply didn't hear us, whereas at high speed (say 40mph plus) tyre noise was obvious. Two things that I had experienced as someone outside a vehicle, but interesting to experience from within.

Are modern cars becoming bloated at the

expense of space efficiency and versatility?

Finally, we have to talk about size. My first car was a Mark 4 Ford Escort which was 4.02 metres long, 1.64 metres wide and 1.4 metres high. The Zafira B is 4.5 metres long, 1.8 metres wide and 1.8 metres high. The Grandland was 4.5 metres long by 1.85 metres wide and 1.6 metres high. So, the more modern cars are obviously larger, but the slightly fatter SUV didn't feel more roomy than than the Zafira which is way more versatile with the ability to fold out to 7 seats (albeit with a tiny boot) or carry loads of stuff. On weight, the Escort was 900kg, Zafira 1,445kg and the Grandland a whopping 1,860kg - twice the weight of the Escort! 

I have had a love-hate relationship with cars over the years, although the hate side of things is probably more around the act of driving where there are lots of other people also driving. Having grown up in suburbia, owning a car was (and I guess still is) seen as aspirational and certainly this is something that car manufacturers have latched onto (amongst other things). These days, they have become a mere tool to me and this year's interesting trip (aside from being fortunate enough to get away) has reinforced my views on practicality and how on earth are we going to physically charge all of these vehicles. 

Maybe I'm a just being a bit of a Luddite, but casting my mind back, at least my old Escort was cheap and easy to maintain, the Grandland has so much technology onboard, it would be a nightmare to own if something went wrong. Maybe that's the point - many modern cars are so expensive, people have to lease them in some way and so the gadgets are all part of the marketing as manufacturers jostle for customers.

Update 7/9/2021

Well, the Zafira fault was terminal. A local mechanic came and plugged his computer in to find out more and it wasn't good news. A fault in the electronic automatic gearbox was the problem and it's one of those things you can end up chasing and investing lots of cash into.

We've reflected and decided that scrapping it was the best way forward and more than that, we've decided to try being car-free for now given how rarely we were using the car which cost the thick end of £1000 a year just to sit there gathering dust. So with the few hundred pounds we got for scrap, we'll set money aside each month for travel and we'll hopefully get out on some train trips in the coming months.

I've owned a car for the last 25 years, but I'm looking forward to not having the hassle of owning a car for a while at least.

Bye bye!

Cycle Tracks In Tight Spaces

One of the issues we sometimes come up against is where we have a road with traffic volumes requiring cycle tracks to enable people to cycle, but where there isn't enough space - what are the options?

Of course, there is always enough space if we are willing to be radical, but for lots of reasons, a road may still be needed to move motor traffic and making wider network changes may be way beyond a project scope or funding. It would be better to be working to detailed plans, but we have to be pragmatic. 

Every place is different and so I can only generalise, but there are some basic dimensions for us to consider. For walking, the minimum footway width given in Inclusive Mobility is 2 metres for most situations, although 1.5 metres is considered an acceptable minimum (1 metre could be used over short sections, but that's all). More space is needed where pedestrian flows are higher, such as outside shops.

For cycle tracks, LTN 1/20 (Table 5.2) has 2 metres as the minimum for with-flow (1-way) cycle tracks for fewer than 200 users an hour at peak, with 1.5 metres being the absolute minimum at constraints. Obviously as flows increase, the space needed increases. For 2-way cycle tracks, 3 metres is the minimum with 2 metres at constraints for fewer than 300 users an hour at peak. 

In the case of walking and cycling, we also need to think about effective (usable) width. People take up physical space and so walking by a vertical highway boundary will have people moving out a bit as they cannot walk right at the rear - there is no guidance, but you'll easily lose 200 or 300 mm. 

Cycling loses up to 500mm where there's a vertical element over 600mm high (LTN 1/20 Table 5.3). There's also the case of having a buffer between people cycling and traffic. LTN 1/20 suggests 0.5 metres (no buffer as the absolute minimum) at 30mph (Table 6.1) and 1 metre (0.5 metre absolute minimum) at 40mph. I'm also assuming that a forgiving kerb is used between the footway and the cycle track to absolutely make best use of the space. Having no buffer also allows stepped tracks to be used which again maximises space and allows overtaking.

We're probably looking at something like the layout above. At this point, the footway and cycle track are both 1.8 metres wide.

For driving, Manual for Streets, gives some suggestions (Figure 7.1). Probably something around 5.5 metres is OK for 2-way general traffic, although on busy HGV and bus routes, 6 metres is probably the operational minimum and perhaps 6.5 metres on bends. Certainly in my experience, different bus operators will have different views and even 6.5 metres gets push-back from some operators.

So, what does the minimum look like? Well, if you squeeze things down, you can fit everything into 11.5 metres, but you'll end up with pretty stingy footways and cycle tracks. Active modes are clearly the most space efficient at 6 metres of the width with driving modes taking 5.5 metres. Of course, if we had 6 metres for general traffic, that's 12 metres.

An operational minimum looks a bit better for walking and cycling which each get 2 metres on each side of a street where we have with-flow cycle tracks (8 metres for active modes) and general traffic gets 6 metres - a total of 14 metres.

This starts to show how much space we need for moving motor vehicles. If we wanted to add a car parking bay, then we'd need another 2 metres. maybe 2.5 metres for a loading bay. This immediately throws up a point that on-street car parking is a luxury we cannot afford in terms of space. What I mean by that is if we are retaining a road as a movement corridor (so we need to protect people cycling from general traffic), then we cannot afford the space for parking. Loading can easily be accommodated by having off-peak loading from the carriageway with or without marked bays - drivers will just have to go around loading vehicles.

There is one more iteration of space efficiency and that's going for 2-way cycle tracks. A 2-way cycle track at 3 metres width isn't bad and would give more space for overtaking. They can be easier to thread through signal-controlled junctions, but they are not easily accessible from the side of the street without a cycle track.

We can go tighter where there are constraints, although I'd bet a small sum of money that it would be the walking and cycling infrastructure that gets squeezed by designers because once we squeeze the space for general traffic, we'll lose two-way running. In fact, this sort of squeezing could actually help create more space for active modes. Let's take our stingy 11.5m corridor and make general traffic one-way.

The one-way traffic lane is 3.5 metres now because we need a bit of space within which to manoeuvre between the kerbs. In this situation, loading is not going to be possible as the road would be blocked, but buses could stop as it would only be for a few seconds. We can grab a little bit of buffer space between traffic and the cycle track, although when used by pedestrians as a refuge space, it is still very tight. Alternatively, we could run with-flow cycle tracks in the same width.

The problem with converting a road to one-way will be where there is a bus route. The usual UK approach is to have bus stops in each direction as it's much more legible for users. In theory, in-bound and out-bound services could be on different streets, but it could mean people walking longer distances to/ from stops. It does depend on how the streets are laid out because some people might be walking a longish distance to/ from a pair of stops and splitting in-bound and out-bound services might actually mean one of the pair of stops is much closer to use and we shouldn't dismiss the idea.

As ever, we are getting into network planning issues because there may not be a road network which supports splitting in-bound and out-bound bus services. Where we have this, then the answer to protecting people cycling is perhaps more of a hybrid solution. If we developed a circulation plan, we could have general traffic running into and out of a town or city centre on different roads, while still running 2-way bus services on both. If we only have bus traffic running in one-direction, we could arrange the cross-section to have people cycling sharing with buses.

This is a 12 metre solution, although mixing with buses in one-direction is a compromise and if the bus direction serves multiple routes, it could quickly get to a point where it feels both really uncomfortable to cycle along and bus passengers get held up too much.

The natural progression from these various solution is to change the street to one where most private motor traffic is removed, but that is maybe a future decision, especially where we are still trying to move freight. Bus gates or sections of bus/ cycle streets can be a solution, but again, these could end up being unsatisfactory for cycling and bus passengers. There is also a consideration on where exactly the space needs to be divided up because within a town centre or city centre, we really should be removing all but essential motor traffic - again, not something a single scheme can usually deliver.

The other issue with what I have been showing is they have a lack of space available for landscaping and planting, so we end up with wall to wall hard surface and as cycling is often being retrofitted, there will be situations where the only space available are existing verges with mature trees which immediately creates a situation where we're ripping out trees for cyclists rather than having the correct discussion about how we take away space for (private) motors.

One cross section to think about is a pretty common arrangement of a 7.3 metre wide carriageway with 1.8 metre wide footways to give 10.9 metres to play with.

Again, having general traffic running one-way opens up space to add cycle tracks and at 1.9 metres wide, it's a compromise, but not the end of the world. 

Even if we started with a 6.5 metre wide carriageway, there is just about an option which can be squeezed in if we use mandatory cycle lanes. We could take the general traffic lane down to 3.1 metres and then have a pair of cycle lanes 1.7 metres wide. Coupled with a 20mph speed limit I think this is getting us to the limits of what we can do, remembering that the traffic lane is still going to be reasonably busy.

With these narrow sections, bus stops are always going to be a challenge because there isn't space to float the passenger waiting areas and we are probably left with boarder style arrangements (below) which I realise are not optimal for everyone and it goes back to network decisions and bus frequency.

Pedestrian crossings are probably a little easier as zebra and signalised crossings can include cycle tracks and cycle lanes in the arrangements (below), although there can be issues with cyclists either not obeying the crossing rules or at least behaving in ways that some pedestrians are unhappy with - that's a wider discussion around how we often treat people cycling as little vehicles, rather than remembering that they are more nimble than they would be driving which opens up different considerations.

Alternatively, we can create shared spaces at crossings which maintain continuity for cycling, but which can create conflict and have signals which present a collision risk (below). Conversely, this type of arrangement might be a little easier to use with a non-standard cycle if the road needs to be crossed so access a cycle track going in the other direction or premises.

Junctions have similar considerations around space. Side roads and private accesses need careful though in tight situations as there isn't space for continuous treatments that could use entrance kerbs or similar if we are going for a stepped track rather than with a buffer. If we have a 2 metre cycle track, we could gently narrow it to 1.5 metres to incorporate entrance kerbs, but detailing becomes a bit more complicated. 

The pragmatic solution is probably to either go for a lower general kerb face and then ramp down to accesses over two kerbs with a low upstand or perhaps use splayed kerbs (below) and require people accessing to have to drive even more slowly. Side streets would need to be flush and so maybe using gentle raised tables for general traffic could be a solution or dropped cycle traffic to carriageway level for a very short distance.

30 splay kerbs used at a private access between the

carriageway and cycle track (vertical elsewhere)

and between the cycle track and the footway.

Signalised junctions are probably a little easier in tight situations and the general road space is more generous. Again, though, decisions are required on the space motor traffic actually needs as we often add lanes for capacity on the approaches. Sticking to one traffic lane gives more space to play with in terms of giving people protection and if the road we are looking at is more about traffic flow in and out of a town or city centre, then banning turns can help, especially if we think about the routing of general traffic at a network level.

It's an interesting challenge to see what we can squeeze into a space, but we really need to be able to think bigger in many cases because the thing that often constrains us is having to maintain two-way operation for motor traffic. Once we can see beyond that, we have all the space we need to enable cycling in many cases. Easy for me to write of course, but the solutions are rarely technical, but often political.

Remarkable Railton LTN

With warm, but not too hot weather forecast, I decided to head off early for another long pootle to see what's changing around London. I like to have an aim and so this time, I headed South Of The River to have a look at another Low Traffic Neighbourhood - Railton, in the London Borough of Lambeth.

The LTN is to the southeast of Brixton town centre and encompasses streets in a broad corridor between Brixton and Herne Hill stations. As with many changes to how streets are used in reaction to the Covid emergency, Railton was implemented on an experimental basis using temporary materials. However, in common with many other schemes, there was actually lots engagement predating the roll out which rather contradicts the usual vocal minority claim that the scheme is undemocratic.

As with other schemes, a local campaign has popped up to stop the road "closures" and remarkably, this includes a few people living within the filtered area (above). 

The scheme has its roots in the Brixton Liveable Neighbourhood project which looked at both the town centre and the areas around. You can still have a look at the Commonplace site for the scheme background and in and around Railton Road, there are plenty comments about how busy with traffic and unsafe the area felt and so it was one of a group of neighbourhoods identified for treatment.

In February 2020, Lambeth started to take proposals forward, just as Covid was entering the news cycle. By June, the council had pushed on with bringing forward a scheme using emergency and experimental powers because public transport capacity was slashed. It's a slightly different arrangement to many of the LTNs I have covered because Railton Road is a bus route which needed to be maintained. This means that the filters used were mainly bus gates, but there's some other traffic management such as the no entry, except cycles on Trelawn Road at the junction with A204 Effra Road (below).

There are also changes to Atlantic Road near Brixton Station whereby a short section south of Coldharbour Lane is only accessible to buses and loading permit holders (below), but there is general access beyond this little buses only section road from elsewhere.

As you can see on the official plan of the scheme below, there are broadly four traffic cells created by the scheme, with the largest being to the southwest of Railton Road itself.

Atlantic Road gives way to Railton Road with a bus gate separating two traffic cells (below). As usual, there is nothing stopping people driving to where they need to get, it's just they may need to arrive from a different direction from what they are used to.

The treatments are simple timber planters with no motor vehicles expect buses signs and bus gate road markings. The filters are enforced by cameras and because it is a bus route, it's probably the only realistic option. As a result, a few drivers will take a chance and this means the area around the filters don't "feel" as safe as they do with a bollard-protected design. 

Further south and just off Railton Road, there is another filter at Shakespeare Road, just east of the junction with Mayall Road (below). This creates around 25 metres of motor-free space and another traffic cell beyond. Although, again, it's camera enforced the layout does rather shout no access to motors.

Personally, I think this filter should have had central lockable or overrunable bollard for emergency access because it's not a bus route. In the fullness of time, this link could be redesigned and I think it would be nice with a short section of 2-way cycle track and landscaped space with rain gardens (below) which could still have emergency access - a mini-version of Old Bethnal Green Road.

Potential longer term treatment for the Shakespeare Road filter.

Further south still and there's a second bus gate on Railton Road which uses two sets of planters to create a very short section of bus only road flanking some open space. Again, this has the potential for future development (below).

I have one very tiny criticism with this filter and that is there is one house and small block of flats within the filtered area. This means that motor vehicles (strictly speaking) cannot stop outside two addresses. I think this has been done so the filter is easily seen from each direction (there is a double bend). It means one needs to walk 20 metres from the filter to the front doors concerned. It's not significant, but it's the sort of thing the noisy minority like to point at and shout "gotcha" - it's really not an issue, but in the interests of objectivity, I am bound to point it out.

Beyond the second filter, Railton Road continues awhile and ends outside Herne Hill Station (below) in a semi-pedestrianised streetscape meaning there is pretty easy access for residents to this and Brixton Station made possible by the LTN.

One thing I did notice was lots of the filters and other temporary street changes had been vandalised. You may have noticed it the photographs so far, but anti-democratic people have tried to paint out the various traffic signs to presumably disrupt the experiment. Well, Lambeth has responded by simply adding replacement sign faces over the damage and there have been recent arrests linked to damage to other LTNs in the borough.

Just to round off the development of the Railton LTN, by the end of July 2020, the scheme was in place and being enforced. In December 2020, early data showed that the scheme had dramatically reduced motor traffic in the area (although there was a slight increase on the Coldhabour Lane). The scheme has also enabled lots more cycling.

As I looked around the LTN, there was some other little features that are worth pointing out. Opposite the Brixton Advice Centre on Shakespeare Road, some cycle parking has been added (above), whilst outside Hamilton Supermarket, a parklet with seating has been installed, complete with a chequerboard/ chessboard (below).

The other lovely little addition is the guerrilla garden I found in one of the side streets (below).

As well as the planters, this little piece of tactical urbanism included seating for small children, such is confidence of local people to be in the street watching the world going by (below).

I was cycling around at about 10am (Saturday) and like many of my trips, I can only give a snapshot of what I see. However, people were up and about with a steady stream of people walking and cycling, the occasional bus and indeed, the odd transgressor of the filters. What was very noticeable was the almost total absence of motor traffic and this made the traffic calming, zebra crossings and centre line road markings look very incongruous in the streetscene (below).

If you think about it, we have in many cases simply allowed driving to expand everywhere to the point where the trappings of managing driver speed and flow spread everywhere. Railton Road looks like a main road because of the engineering, and to that extent, the addition of a handful of cheap filters with some CCTV cameras have actually solved the problems the traffic engineering which cost many times more failed to deal with.

As ever, it brings me back to the point that we can cheaply deploy LTNs to manage the operation of entire places. Instead of investing to try to accommodate through traffic away from main roads, the bulk of our budgets can be used on the actual main roads in terms of walking and cycling protection as well as high quality public realm.

I'll leave you this week with a little cycle through the Railton LTN. In the meantime, you might want to follow the @RailtonLTN Twitter feed to find out more about this wonderful scheme.

Rain Gardens

One of the impacts of climate change for the UK is that storms are going to get more severe with greater intensities of rainfall. Unless we start climate-adapting our streets now, we had better start getting used to flash flooding.

I should at this point check our privilege because there are places in the world who have long suffered catastrophic flooding and consumption by rich countries has and will only make things worse; by comparison, the UK has been getting off lightly.

I need to separate out a couple of the flooding mechanisms. At the macro-level, there will be issues with how a water catchment operates. By catchment, I mean the area that captures rainfall (or melting snow) which ends up in watercourses. In towns and cities, this will be the rivers that flow through them. The macro issues are those around the ability of land upstream of a place to hold water, because if it doesn't then surface water is going to move pretty quickly through the system.

Flooding where a stream turns into a river and

bursts its banks because of surface water is piped into

the stream further up the catchment.

At the micro-level, we're interested in what happens locally (and which is my point of interest this week). We need to be tackling lots of issues, but a town or a city doesn't necessarily have control or influence about what happens upstream, but it does within its own area. Local influence can deal with some of what is coming towards an area in terms of surface water management and reducing what is sent on to other places downstream.

So, we're interested in three things and they are capturing rainfall near where it falls, holding onto it for as long as possible and doing this in as many places as we can. The first two points are about source control; that is dealing with the problem or hazard where it occurs. If we can capture rain where it falls ad hold onto it for as long as possible, the storm event will have passed and the land or drainage system will have more capacity to deal with it. 

A typical suburban street. Wall to wall asphalt and

front gardens paved over for car parking. A system which

fires rainfall straight into the sewerage system.

The third point is about building resilience on the basis that it is better to have many small treatments dealing with rainfall rather than a few large ones. If a small treatment gets blocked or overwhelmed, there are many others to take up the slack. If a large treatment gets blocked or overwhelmed then there isn't anything to step in. This is where "rain gardens" step in, one of my favourite street elements and which are part of a much larger family of treatments known as Sustainable Drainage Systems (SuDS).

A rain garden in Enfield on Cycleway 20.

I'm using the term a little loosely because there are subtleties in their design and operation, but I'm most concerned with the ability to hold water and release it slowly, so performing a "detention" role. Depending on the application rain gardens can also treat surface water run-off, or at least have it entering the drainage system a little cleaner. This would be performing a "bio-retention" function whereby water is filtered and the organisms within the root structure of plants in the rain garden break down hydrocarbons and other pollutants.

A rain garden being used at the spout of a roof downpipe

getting right at the source. Basildon Hospital, Essex.

The components of a rain garden are fairly simple. The layout needs to allow water to enter the feature and there must be a volume of space which can fill up. There needs to be an outlet for the water when all of the space has been taken up otherwise the feature will simply overflow back into the road or paved area. Planting needs to be able to stand a variety of temperatures and degrees of saturation (including being wet for periods of time). There also needs to be suitable planting media to support the plants. It seems to come as a surprise to some people that chipped bark simply floats away! 

A small rain garden installed as part of the

Greener Grangetown project. Cardiff.

The rain garden doesn't necessarily have to be impermeable. Some subsoil types allow water to percolate directly into them such as ballast. This type of rain garden is an infiltration basin and depending on the situation it might be an appropriate approach, although if the subsoil becomes waterlogged you still need storage volume. Of course, clay soils are pretty impermeable and so water will sit on top of them. 

In some schemes, large retention cells are sometimes used for additional water storage and some systems add substantial tree pits. The approach can scaled to whatever is needed.

The image above shows a cross section of what a simple rain garden would look like retrofitted in the street. The area holding water is set out within a kerb line and on the carriageway side, there would be a series of slots allowing water in. The level of the planting media would be lower than the carriageway to create a clear volume of storage, but of course, the media getting saturated is also storage. An existing road gully becomes the overflow when water in the rain garden fills up to carriageway level.

New Bailey Street, Salford.

It's fairly simple technology and in terms of maintenance, the gully grating is easy to get to and the slots in the kerbs can easily be swept clean - that's another key feature of resilience - easy maintenance created by designs you can get at to clear blockages. It's a pretty simple thing we could retrofit and with a bit of planning, rain gardens could be rolled out during major maintenance works.

London Cycleway 4: The Moment Cycling Infrastructure Gets Boring

The title of this post seems like a criticism, but you couldn't be further from the truth. The fact that London's Cycleway 4 is boring is an astonishing thing and needs celebrating.

Back in 2016, I wrote the following statement;

"Luckily for us, we now have stuff we can go and point at and to be honest, me writing blog posts on it will no longer be necessary as the infrastructure becomes boring and ordinary!"

This is the 456th post of a blog, not far off from its 9th anniversary and at least on UK cycling infrastructure, I can say that in that time since I started writing we have gained many examples of well-designed and implemented schemes. Reporting on them is now almost mundane and that's a wonderful thing.

Cycleway 4 in London will eventually run from Tooley Street (just west of Tower Bridge) to Creek Road in Greenwich, providing a main cycle route for lots of people in the southeast edge of Inner London giving direct access to the centre. It also starts to connect to some of the quieter parts of the Cycleway network (former Quietways) and so is a significant part of the jigsaw for Inner and Central London. It does also highlight the stark lack of cross river possibilities in this area given how hostile Tower Bridge and (more so) the Rotherhithe Tunnel are to cycling.

The section from Tooley Street to Lower Road (by the Rotherhithe Tunnel) is my interest this week. The section was opened in the Autumn of last year and utterly transforms a really busy road traffic corridor.

The route runs along the A200 which is not really a primary road (the parallel A2 does that job), but still a busy corridor for people driving across this part of London. Having a direct connection to the aging Rotherhithe Tunnel means that for the meantime, there's still going to be lots of demand. The photograph above is on Lower Road with the roundabout at the access to the tunnel to the right.

It's a direct route for cycling because the development which flanks the River Thames is pretty piecemeal and although the Thames Path is available, it's somewhere to pootle along rather than making useful transport cycling progress. The A200 is flanked by lots of residential development on both sides and so a route through the middle of that give a large base of people who can access it.

From the tunnel roundabout, there is also a handy link into Brunel Road which creates access to a large neighbourhood to the north of Rotherhithe (above).

The scheme itself is largely a 2-way cycle track on one side of the road. It's generally 3.5 metres wide and as there are plenty of bus movements, the stops are all floating with zebra crossings to access them (above).

There are plenty of signalised crossings along the route, with many of them being toucans to help access streets on the opposite side of the cycle track. One of the failings of 2-way cycle tracks is that if live on opposite side of the street to the track, then accessing it is a pain (below). There's also the same staggered arrangement between crossing the cycle track and main road which unfortunately degrades accessibility.

The 2-way cycle track on one side of large roads is something London and other UK cities have gone with because it makes threading them through traffic signals easier, it's more space efficient and where lots of commuting is expected, they can operate tidally.

Being nice and wide does allow some side by side social cycling while giving space to overtake which is of course a positive (above) - I just wish Transport for London ran the centre line all the way along the cycle track to make it very clear that it's 2-way.

At the junction of the A200 Jamaica Road/ West Lane/ Southwark Park Road, the cycle track changes sides of the road - south to the east and north to the west. I don't know the reason why (it might be for bus movements), but from a cycling point of view, one can at least can access the side streets which is useful. The swap over also puts the cycle track on the opposite side of the road for the Bermondsey Underground Station which makes station access more difficult, especially as there's no toucan crossing to it.

The junction with Bevington Street (above) is a good demonstration of why 2-way cycle tracks are used. There are banned traffic movements at the junction which means cycle traffic runs with main road traffic so there's no lost time giving a separate stage to cycles. There is network level though going on as drivers can still access areas both sides, it's just they will be doing so slightly differently than before.

There are some side streets crossing the cycle track without signals such as George Row (above). The crossing points are bent out from the main road so that turning drivers can stop to let cycle traffic pass or wait before entering the main road. The layout of this is annoying similar to those built by TfL in the last several years because to the driver, it looks like a conventional junction where they have priority. I would like to see "entrance" kerbs and continuous treatments used in situations like this to give better priority to cycle traffic and priority to walking.

One nice junction feature at the junction with Abbey Street (above). Abbey Street isn't great for cycling, but accessing it from C4 is fully protected both cycling in and out. The pedestrian crossings on the main road are staggered which is again unfortunate, but cycle traffic gets to cross in one stage. The pedestrian crossings are floated from the north side which means cycle traffic can be accommodated within the arrangements.

The even more useful junction arrangement is at Tanner Street. C4 continues west into Tooley Street. Eastbound general traffic has to turn onto Tanner Street (as Tooley Street has a bus gate) which is part of a much more complex arrangement for general traffic in the area. Cycle traffic, however, it protected in all directions (above) and is safety threaded along Tanner Street which becomes Cycleway 14 (previously Quietway 14) which is another very useful route as it links to C6 and C7. In other words, we are starting to unravel the cycling and motoring networks and one needs a completely different mental map for each.

One oddity of Tanner Street is a floating bus stop where pedestrians have to cross twice as the stop is also the footway (above). Although it is well laid out, it does represent another compromise for people walking, although space has also been taken from general traffic as it used to be 2-way here.

Cycleway 4 has the same good and bad bits about it as the other high-quality Cycleways in Central London. There are kerbs with upstands which can grab wheels, pedestrians get more crossings, but some are staggered and only half the road frontagers are well served by the cycle track. But, a traffic-sewer has been transformed. People now have another real option for their journeys as this part of London has been opened up to cycling. The scheme is a well executed and quality job with a really useful connection to C14.

Cycleway 4 is an example of what we now expect to see. There is consistency with C3 and C6 and to that extent, it feels familiar to use. In fact, it is that familiarity which makes the infrastructure boring. Not having to concentrate on cycling now means the senses are elsewhere and that is the triumph. I'll leave you with a video of the route in all of its mundane and wonderful detail.