Thursday 19 November 2015

Learning Pathway

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!



30 comments:

  1. Alarming puddle in photo 7.
    Looks like a drain near the lamp-post when finished - was that added as an afterthought ?
    I would have thought drains would have to be done first !
    Nice work - good post - thanks.

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    1. Do you mean the one in the middle of the track? That one is a manhole which is the head of the surface water drainage pipe run to make it easy to clean out.

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    2. No, I meant this puddle
      http://1.bp.blogspot.com/-eSTmBMMto-U/Vk4fL5annTI/AAAAAAAADxc/izEoHfrAMBU/s1600/5.JPG
      but looking at the full resolution version, I can see that the drain is standing proud of the water surface which would explain why it wasn't draining. Once the surface is built up, I'm sure it's fine now.
      Good work !

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  2. How is the key for the bollard controlled? Is it a standard key for all padlocks controlling bollards on fire access roads? Who has access to this key? Just the fire brigade?

    Interesting post thank you.

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    1. Yes, standard fire brigade key. In action, the track is very unlikely to be used at the start of the emergency; more likely that it would be opened up well into an incident if the brigade need to get kit in to assist and the main site road is blocked.

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  3. Coming from a dutch persepective, I would probably say something like "so you build a standard cycle path, what's the big deal?". Which, from what I've read on this and various other blogs around the web, is a reaction I wouldn't be able to give to most of UK cycle infrastructure. Wonderful proof of concept, great job!

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    Replies
    1. Thanks for the reply. Yes, that is the point - I would love to be in a position when I don't need to blog about UK cycling infrastructure!

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  4. Very nice. Could you give us some costings for that spec?

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    1. It will be in the region of £150 - £180 per square metre; it was built by the developer and there will have been good prices because it is part of a massive development.

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  5. could the bollard be installed with the handles parallel to the direction of the path rather than orthogonal?

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    1. Unfortunately not, our usual spec is the 80mm medium duty version - this is the heavy duty version. I think when we take it over (as it is not yet adopted), we'll cut them off.

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  6. Mundane is good; more schemes like this are what are needed to build that 'dense grid'. Agree that rough costings would be useful; £x per metre of straight run and £y per junction. Appreciate that costs won't be linear and may be sensitive but some idea whether it is £10 or £10000 pm would be nice. Assume better foundations should reduce ongoing maintenance, don't know whether anyone will be monitoring to confirm. As the construction details are important and unusual for the UK did the contractors need extra monitoring to keep to spec? Finally, why the month-long gaps between phases of construction?

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    1. Costs are always tricky as sites vary, but for this type of work we have to move away from thinly constructed paths which move around and fail and eventually need reconstructed and build as we would roads. Where only cycle traffic is present, we will only need to maintain the surface with the odd resurfacing every couple of decades at worst - build once!

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  7. Quick query, you state "A waffle grid gully which should be standard if cycles go anywhere near it." My interpretation is that this type of gully would be the correct choice on every road which isn't a motorway then? Should this just be what all gullies look like or are there circumstances where it's inappropriate?

    Or are there still Highways Engineers who say "Oh, no one cycles round here so we don't have to design to make that possible"...

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    1. Interesting point. It is a good idea to cycle away from the channel in any case because of debris (even on this cycle road) and so the "depends" comes to mind. They do take a bit more maintenance as the grid is more easily clogged up, but as a standard detail for new build and for a replacement policy, it seems a good idea.

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  8. Question; Should/could the 1003 and 1009 give-way and edge of carriageway markings have been the half size variants?

    Andy R.

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    1. To be honest, it didn't occur to me until you had pointed it out. Perhaps I have associated half sized markings with weedy little cycle track schemes rather than a cycle road! ;)

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  9. Did you use a red dye for the tarmac on the bike path? Does the equipment for laying down the red tarmac have to be cleaned out before using it for black tarmac or other colours?

    In Edinburgh you get cycle lanes with red chips in black tarmac, and white chips for car lanes. Its not as visible as red tarmac but its easy to change chips when resurfacing. https://goo.gl/maps/PkLXe2bW3R42

    I wonder if its as easy to switch colours if using red tarmac?

    Iain

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    1. The chips in your example will be with hot rolled asphalt and are applied once the surfacing is laid, but still hot. I am a fan of HRS, but my recent experience from a cycling point of view is that surfacing such as the one in my example is a lot smoother (as the chips put in after are bumpy).

      In my example (asphaltic concrete with a 10mm stone size to be precise) the red is in the bitumen binder (and the stone can be red as well) which is mixed at the plant. the batching plant and the surfacing machine do need to be cleaned when changing to black otherwise we can get some crazy streaks!

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    2. How much more expensive is the red bitumen than black bitumen? In pounds sterling/square metre.

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    3. I wonder how to make a good argument for using red Asphaltic Concrete instead of red Hot Rolled Stones given the extra effort needed on cleaning the batching plant and surfacing machine?

      Red HRS is not that obvious in poor lighting conditions, so there is the visibility argument.

      Thanks for the reply! Iain

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    4. Very roughly, based on a 35mm thin surface-course system;

      £11 sq.m for black in small areas (less then 500 sq.m)

      £6 per sq.m in black for areas over 2500 sq.m

      The additional costs on top for red (as an extra-over) is about £11 extra a sq.m for less than 500 sq.m and about £8 extra per sq.m for over 2500 sq.m. (ish)


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  10. Do you know if it is legal or possible to create an uncontrolled junction, no signals, no signs, no markings, in a 20 mph zone, on a raised junction up to footway height?

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    1. Yes - nothing in law stops that on a 50mph road (but one wouldn't do it!). It is about context and location - you are essentially describing shared space (which needs to be carefully used in my view).

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    2. I said 20 mph one. Though thinking about it, having it in a 40 mph zone is also used in the Dutch country side. The idea is not shared space, there would still be separate sidewalks, still different surfaces, and extremely low volumes. Less than 2000 vpd.

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    3. With 20mph, things are even easier to leave out in terms of road markings and signs and in the UK are not required.

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  11. I suggest that if you do something like this again with the bollards, look into plastic bollards that look fairly solid but will bend easily, but not deform, in response to a cyclist hitting it. I also suggest using trees instead of bollards that are used that do not control access to the cycle track. This makes it more pleasant and less cluttered.

    The Dutch have new striping measures to hopefully reduce the injuries and deaths associated with cyclists hitting bollards. As a bonus, you get to see how the plastic bollards work: https://youtu.be/KVF9jUUe2go

    I also suggest striping bollards, and for that matter, just about every pole on or near a roadway or cycleway that is within the zone that should be kept clear of obstacles. Traffic light poles for example would be striped like how the poles for belisha beacons are striped. For those poles, black and white is used in the Netherlands, for bollards on the cycleways, it's usually red and white striped. This should make bollards a smaller problem.

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    1. I've used trees to good effect and we do have flexible bollards we could use. The problem we have is allowing the bollards to be removable for fire brigade access. There are no UK suppliers which do a flexible bollard which also has a standard UK fire brigade lock, but I am contacting a few suppliers to see if I can get them to develop such a thing!

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    2. The flexible kind can be so flexible that a whole firetruck can go over them. And if the department really needed to and people were going to die otherwise, they'd just run over a flexible bollard, insurance can hopefully write off another bollard like that if the bollard is too damaged.

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  12. The Dutch do drainage on roads and cycle paths like this: https://i.ytimg.com/vi/z75fqfp37KI/mqdefault.jpg. And in more modern installations, I challenge you to even find the drains: https://www.youtube.com/watch?v=dMOmMje0WU8.

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