An interesting little quirk of UK cycle track design popped up this week and I thought it might be interesting to look a bit closer.
The subject is shared-use paths being given priority over motor traffic which was being discussed on Twitter earlier in the week in terms of making them as good as possible against the backdrop of a local authority refusing to look at separate walking and cycling space. Thanks to @24bitwarrior for the question and to @walking_boston for the link to an older piece of guidance from Sustrans.
Coincidentally, Adam Tranter tweeted a photo of exactly the thing we were talking about later in the week;
The location is here and if you have a look around the area, the treatment is unique, although it's at one end of a network of shared paths. It reminded me of a similar layout in Crowthorne which you can see here - there are others in the UK and it would be quite nice to compile a list, so feel free to tweet me locations.
The locations take a similar approach where you might have the shared-path (which strictly legally speaking is a cycle track which is shared with people walking) running next to or set back a bit from the carriageway and where it meets a side road, it is "bent out" from the main road as it crosses the side road. Bending out means that drivers can get off the main road before having to stop for cycle traffic.
As you can see from the diagram above, drivers would turn off the main road into an area at least 5 metres deep to give way a second time to cycle traffic. Apart from the design being used in New Town style estates, we know these are historic because the crossing is on a hump commensurate with the regulations at the time. Current regulations don't require a hump, but in the context we're talking about, I think humps remain useful to reinforce priority to cycle traffic and provide a level surface. We also often see red asphalt which lost favour in the UK (so did building cycle tracks of course).
Here's another clue. The photograph above is from "Cycle Friendly Infrastructure", a design guide from CIHT dating back to 1996. This actually has a separate footway, but the concept has been around for years and a study was undertaken by TRL in 2000 looking at this type of layout (with various configurations).
The TRL conclusions essentially fell back on the government's hierarchy of provision which is to make conditions suitable for cycling. 20 years on we know this doesn't work and if you need a cycle track, then surely the carriageway isn't suitable for cycling - this design has been used on distributor type roads which are awful for cycling.
TRL more sensibly concluded that the traffic volumes in the side road should be low, perhaps under 100 vehicles per hour (which I am assuming is the two-way flow as it isn't clear). They also suggest that good visibility is required for people cycling to see and be seen (with commentary on main road flows) and that space is needed for the bend out layout.
The other issue is the layout of the junction looks like a traditional driver-oriented layout which invites motor traffic priority - the give way markings used in this way are going to be unfamiliar to many drivers.
I would also comment that the main road layout and volume will be an issue. A right turn pocket should be provided so that a right turning driver can pause before making the turn. This means they can see the side road layout and the need to give way to cycle traffic. Without a right turn pocket, people will have to find a gap in oncoming traffic and see the side road layout in one go.
A better approach altogether would be to have the side road as one-way out onto the main road which removes some of the conflict. With an estate, traffic signals can be used to manage conflict where 2-way traffic is required. The layout doesn't really seem to have considered people walking. We should be providing tactile paving which means on a shared-use path, people have to cycle over them which can be uncomfortable and slippery.
I'm not entirely sure about the priority issue in terms of pedestrians either because strictly speaking, the give way road markings are about vehicle operators giving way to other vehicle operators, so people on foot might be in a grey area. We could in theory make the side road crossing a zebra, but for cycle traffic, we'd need to fudge in a parallel crossing.
Going back to the original question. I think it is going to be difficult to build shared-use paths with decent priority that people cycling can be confident with in terms of drivers giving way with these older layouts. I have less of an issue with shared-use paths in rural places where people walking are going to be a rarity, but in urban areas, they are poor for walking and cycling.
My thinking is we need to make the side road look like a side street, so we'll use our new entrance blocks at either end of the junction approach for a change in level with the carriageway width taken down to 4.8 metres to keep things nice and slow. The shared-use path should be a contrasting colour to the road (I like red) and perhaps flank it with some cobbles or setts to help with visual priority.
The area either side of the cycle track will be a contrasting material to the carriageway and shared-use path - perhaps grey block paviours would work. We can also introduce tactile paving, 800mm deep either side of the area which drivers traverse because visually impaired people need help - set them back a bit from the area being over-run by drivers to keep it looking less like a road.
The image above puts these items together, but clearly, a council which wants to put in shared paths won't want to spend money on junctions. They'll leave it like a traditional junction and people cycling will have to give way.