I have been meaning to write a post about a little scheme I have been working on (a team effort). It is nothing compared to what we are seeing in places like Central London or Leicester, but it is home grown and it makes me happy.The scheme is linked to development of several hundred homes and the where and the why is not important. What is important is that as part of the planning consent requirements, the development had to have a secondary fire access as the wider site is not permeable for motor traffic; this access was also to be provided for walking and cycling. The development has opened up new walking routes which make the wider area more permeable and cycling benefits too, although there is a shared-use path through the site which could have been much better (planning consent was granted in 2006, so modern opportunities were missed). Yes, this is a tiny scheme, but (almost) perfectly formed.
Fortunately, there was the opportunity to influence the fire access and rather than the original basic shared tarmac path, we convinced the developer and their designer to go with something a little different and unique (at least in my neck of the woods). Now, as you might realise, I am coming up to my third blogging anniversary (that will be a future post) and so I have seen one or two bits of infrastructure in that time. With this scheme I have been able to throw some ideas into the pot from things I have seen on my travels. Two things have stuck in my mind and they are a walking and cycling link in Bermondsey, London and a section of cycle track along the A48 in Port Talbot, South Wales.
|Bermondsey. A nice machine-laid track, in red asphalt|
and with a separate and kerbed footway. Completely
intuitive to users and nice safe space.
|A48, cycle track on the left, stepped down from the|
footway and the first time I had seen a 45 degree
splayed kerb used in the UK.
OK, I have been influenced by an awful lot more than just two schemes, but the basics are there and it was just a case of putting them together. OK, time to show you what we built;
Taken a while back, this shows the site corridor cleared and a capping layer laid (essentially a road foundation made from crushed rock or concrete waste). The guys on site are laying various kerbs with those either side being British Standard 45 degree splay kerbs, 255mm deep by 125mm wide. We could have actually use kerbs 150mm deep to get the same effect and this was a bit of a learning point, although they would have had a thicker capping layer below. The important point is that the capping extends beyond the kerb lines and so the kerbs are properly supported. All too often, paths are built too thin and the kerbs supported (on the usual concrete bed) directly on the soil. After a while, a crack appear along the path as things move because of the lack of support.
Further up the site, a view of the capping layer with kerbs freshly laid. The capping layer essentially helps transfer the traffic loading from the heavy duty and expensive surfacing down to the original ground which in this case is fairly soft clay. This scheme is no different to a mini road scheme in terms of design and construction. A far cry from a thinly constructed and badly surfaced shared-use arrangement.
Fast forward a few months and all of the kerbs are in and the sub base layer is in. The sub base is a higher quality than the capping (and a bit more expensive - you see theme here!) For this scheme, we used a hydraulically bound mixture (HBM) for the capping and sub base. There is a bit of science involved and the thicknesses are based on the strength of the underlying ground - yes, a mini road! HBM uses cement and some recycled soils (produced on site in this case) and acts flexibly and provides a replacement for some asphalt thickness. A good product if properly controlled and installed.
This photo shows a junction being formed with a road within an existing estate that this link connects to. The estate is very quiet and through traffic is excluded, but walking and cycling is permeable beyond the traffic filters. The junction has 2 metre radius kerbs and dropped kerbs with the usual tactile paviours. It has been suggested that this could have been a continuous footway. This is true, but there is a footway on the left and a full height kerb was appropriate opposite it to assist visually impaired people. Notice proper transition kerbs from the 45 degree splay kerbs to the dropped kerbs.
A view down the site with everything ready for surfacing. Actually, apart from forming the junction, most of this was built for months and the use of HBM meant the sub base could be left exposed to weather without needing to cover it up because of the cement content - crushed rock or concrete would have been affected by the weather.
Fast forward a little more and the job is done. This is the view on the existing street showing the little cycle junction. We had to install bollards because car drivers cannot be trusted, but they are set back 4 metres so that people on all kinds of cycle can complete their turn and the straight before they pass through.
A view along the track. The cycle logo is one of two (one at the other end) and this is the only signage to indicate that the road is for cycles (wayfinding coming in the future). The arrangement of the separate and raised footway means there is no need at all for any signage or tactile paving (apart for the junction). Nothing is needed to tell drivers to keep out, the bollards say that, along with the logos which say why! The cycle track is 3.1 metres wide (suitable for a fire path) and the bollard is 100mm wide (and removal by the fire brigade). This gives 1.5 metres of tarmac each side of the bollard. The bollards are at 1.8 metre centres
The bollards here are well back from the pedestrian route along the main street and so out of the way. We are aiming to paint some white banding for a bit more conspicuity.
The footway is 2 metres wide and the cycle track 3.1 metres wide, excluding kerb widths. The road markings are standard with 4 metre lines and 2 metre gaps approaching each end (which act as a warning) and then 2 metre lines and 4 metre gaps in the central section for guidance. Totally UK standard.
Splay kerbs with a 75mm upstand and no vertical upstand to maximise safety. All UK standard materials available off the shelf. A shallower angle would be better for potential overrun and a lower kerb face would be less likely to catch pedals, although users will be in the centre of the lanes and this won't be swarming with people - it's just a link.
Extreme close up! Some very nice surfacing skills!
Bog standard AC10 surfacing in red for the track at 40mm thickness. There is a thicker layer of asphalt underneath for structural purposes and both are machine-laid.
Black AC10 for the footway. In hindsight, a light grey block paved footway would have looked nicer I think, but this still gives a very high level of service to pedestrians.
The other end of the cycle track connects to an area which moves from usual carriageway and footway construction to a level surface shared space which is the access to a few homes. Here, the kerb-separated footway continues on to a spine road through the wider development.
A waffle grid gully which should be standard if cycles go anywhere near it. Actually, we have found out since that we could have got a 45 degree splay kerb inlet gully - one for the standard construction details being worked on!
Closer view of the bollard. Not sure about the handles, but they are there to help with lifting out the bollard. We didn't go for a fold-down bollard as some fool always leaves it down which is a hazard.
Approaching the cycle junction at night. Might need double yellow lines to stop the stupid parking.
The whole link and night - there is a lighting column about half-way along. A good view of the second cycle logo.
Both ends of the scheme pass the trailer test easily.
Photos are one thing, but I have also made a couple of videos of the link. The first is simply a ride along the cycle track. The second spares no personal safety as I bounce my bike up and down the splay kerbs a couple of times and then try a nudge at the end. It was on the bike in the photo above. While I don't recommend it (and there is no need to go close to the kerbs with this path), they are kind of forgiving!
My colleagues and I have had fun with this scheme to be sure, but there has been wider benefits beyond people being able to use the little, 65 metre long link. Two things spring to mind.
First, we have learnt from it in terms of using the splay kerbs correctly (and yearning for a more forgiving UK standard kerb), how to do the drainage better next time (into the kerb line), playing with the red surfacing and all of the other layers which built this mini-road for cycles. We have also shown how a track of an appropriate width can be accessible for all and also, that we don't need to plaster the street in tactile paving and signs to explain how to use it, the route is completely intuitive. There is a debate in the office with the maintenance guys who are nervous about reactive repairs to the red surfacing (potholes mainly) and inevitably, they will blog black tarmac in. If the footway had been light grey, a black track would still have been fine. A black track and black footway would have done the job, but it wouldn't have looked as nice (in my view). The debate will continue, but we have built this scheme pretty bullet-proof.
The things arising from this scheme are being incorporated into some standard construction details and the scheme is influencing our thinking on other projects. To be honest, this design is very similar to what is being built in many parts of London (although we have done the kerb upstands right!)
Second, we have something tangible we can show other people when we are talking about potential new schemes and designs. Already, I have sent photos to people to explain how we want to see future links of this nature built; of course, we can also take people out on cycles to show them what a proper job looks like. Many designers are still stuck with proposing 3 metre wide hand-laid tarmac paths. This kind of design shows what is required in terms of space and specification if we are really treating cycling as a mode of transport.
But, I don't want to get ahead of myself, lots of people are building huge schemes which are doing so much for cycling. This is one scheme in a big city and it doesn't make a network, but we have to start somewhere and I don't think this is a bad scheme for moving the debate on locally. I truly look forward to the time where this type of thing has no interest to anyone, as it is standard, normal and mundane. Of course, I like to celebrate the mundane!