You might have read the title and thought: that doesn’t sound very interesting or consequential! And perhaps you’re right, but I wanted to write a blog about an interesting design feature I’ve noticed on recent Greater Manchester walking and cycling junctions. Note, this only applies to those which use bi-directional cycle paths and crossings: many of the simpler “CYCLOPS” designs only have single-direction cycle paths and so don’t have this feature. I am talking about a peculiar central island at the start and end of each cycle crossing. Here is a photo of an existing one at Deansgate Interchange, Saddle Junction, and a plan of new ones being built at Princess Road Roundabout
First 4 seconds: “See, why are we wasting money & space on bike-lanes nobody’s using?”
Rest of the video: “…oh…well, it must be flat there.”
More people moving in less space with less public cost, emissions, health care costs etc. HT @CyclingWorksLDN pic.twitter.com/hEksGLYERd
— Brent Toderian (@BrentToderian) October 23, 2020
The main issue I have with it, is that it narrows the cycleway. As you can see in the plan above, for a ~4m wide footprint, we only get 1.65m for each direction of cycles. This is barely wide enough for two abreast if riding very close together, but most people will go through this pinch point in single file. Since cycle stages are often quite short on large roundabouts like this (except when “hold the left” phasing is used), this means that the cycle capacity is often quite low.
In the summer, there was an A56 popup cycleway support ride, and a few of us went across Deansgate Interchange. Due to the low capacity of the crossing, and short green times, it took us 4 signal cycles, and several minutes, to get all 30 people across the junction.
The Dutch have known for a while, that not only is a large effective width at crossings vital for high capacity, but also a “chip cone” shape of crossings can improve capacity. As BicycleDutch’s brilliant article and video explains, the optimal shape for a cycle crossing is as below: