Sunday, 31 January 2016
Safe road crossings.
I wrote a few days ago about how a cycleway can safely be crossed by a minor side street when the cycleway is parallel to a main roadway with yield sign control. I have yet to finish off my traffic light series with simultaneous green and what to do if you can't fit a fully separate turning/cycleway signal system, but I can write now about what happens if a cycleway needs to cross a main road without traffic lights when it's not parallel to a roadway. I was inspired to write this by the post from Aviewfromthecyclepath talking about cycle priority crossings. I'm not writing about priority crossings as the sole topic, but it will be one of the primary topics.
Visibility is one of the key factors that makes a crossing safe. Especially if cyclists have priority. It makes it so that you can understand who will be where at what time. At least a lot easier. David found a chart, link here: http://4.bp.blogspot.com/-Lf8_NGn4rbM/VW7jJTsKmrI/AAAAAAAAYj8/AQNz2QfrP04/s1600/Screenshot%2Bfrom%2B2015-06-03%2B12%253A56%253A35.png, that describes the sightlines required in relation to how how fast the road is and how wide it is if cyclists are assigned the right of way. You can see that a huge amount of space is required to make a priority crossing safe for 50 km/h speeds (85th percentile, not necessarily posted limit) than for 30 km/h crossings, and so on.
Speeds at the crossing is the next big task. There must be low enough speeds to make them safe. I would say that the maximum a safe crossing can be with priority for cyclists without a traffic light is at 50 km/h. Possibly at 60 for rural access roads, but I have doubts about that. Because this is measured speed, not posted, there must be things to make drivers want to be at the speed limit in question. A bend in the road helps a lot here. For the most part this bend would be very difficult to build, but I found a location in Edmonton where such a crossing could be retrofitted. More on that later.
Drivers must be able to know with confidence where cyclists are going. If there is an intersection between cycleways near the intersection, then it makes it hard for drivers to know whether cyclists are going to continue onto the road crossing or are going to turn beforehand. This means that cycleway intersections should be located well back from the road crossing, or if you can't do anything else, offset the roadway crossing and the cycleway intersection, creating a pair of T intersections separated by a number of metres.
Drivers must also know who has the right of way in an instant. Look at this image: https://firstname.lastname@example.org,-113.5148711,3a,90y,160.71h,78.85t/data=!3m7!1e1!3m5!1s_Q5gGHZj1ARF3W7O3XQ0kA!2e0!6s%2F%2Fgeo0.ggpht.com%2Fcbk%3Fpanoid%3D_Q5gGHZj1ARF3W7O3XQ0kA%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D91.306839%26pitch%3D0!7i13312!8i6656?hl=en. You have no idea who is supposed to go first by design. There aren't markings, no signs, and nothing to slow cars down other than a 10 metre wide corner radius, which isn't that small which can increase to a 15 metre wide effective radius if you move a little bit away from the curbs. With that only maybe 60% of the motor traffic will yield to pedestrians and cyclists, even if they are aware that such a path exists. The crossing isn't at a right angle either, even though it is perfectly possible to put about 5-6 metres of space between path and roadway edge. Elephants feet, yield signs and yield triangles plus the continuation of the red asphalt of the cycle path and when crossing access roads, a continuous level sidewalk too, otherwise zebra markings, all on a hump help to make it very clear that cyclists should go first, and a drop down to roadway level, facing a yield sign and having the sharks teeth point towards you and narrower dashed lines flanking the crossing rather than elephants feet plus a break in the surface of the cycle path, using the surfacing of the roadway makes it clear that cars should go first in that instance. This is visual priority, when you know for certain who should go first (coined by Schrödinger's cat from the Alternative DfT).
Breaking up the crossing(s) into simple easy to follow steps is useful too. A median refuge, even if cyclists have the right of way, and especially if they don't, can be really helpful. Having the ability to turn off a main cycle path before you cross a road, for example when you are cycling parallel to a main roadway and need to go onto a minor route and to do so you would cross the road, being able to turn off the cycle path and use a secondary path for a short distance before you cross the road helps a lot.
The roadway should be as small as possible, especially if cyclists have the right of way, so limit speeding, to limit the number of things that a driver might doing instead of looking around for cyclists, like finding a parking space or overtaking, and to make it a smaller crossing with less risk and fewer things for the cyclists to look out for, like an overtaking car.
Too much reliance on things like amber flashers shows that there is likely a problem with the crossing itself. They can be helpful in some cases, but should not be the main go to alternative for other physical measures. They also should be activated by loops or microwave detectors or something like that from a distance so that you don't have to stop on a bicycle to push a button. The over-reliance problem is a problem because it entirely depends on a driver being conscious, alert, at the best mental capability and is willing and going to react and not distracted. With a good physical design, if a car is for example not going to follow the curves on a roundabout, then they are just going to crash into the curbs on the central island or splitter island or into the curbs on either side of the lane. If it were a traffic light or stop then, then you might crash into another car or cyclist or pedestrian. Same with these priority crossings, a bend helps a lot in that if you don't slow down, you are going to hit the curb not the cyclist.
If cyclists do not have the right of way, then they should face a yield sign to the greatest possible extent, not a stop sign. There are a few locations I can think of which do need stop signs, but not nearly to the extent they are used now. If you didn't have to fully stop, then you are more likely to want to obey the yield sign. The curves should also be tighter for cyclists if there is a curve and a bend for the cyclists is a good idea. This is how roundabouts work in Assen. There must be gaps in the flow of traffic. The speed must also be regulated, and you must be able to decide whether in each lane that motor traffic has that there is enough of a gap. This is why multi lane unsignalized crossings can be very difficult, and especially when there is no suitable median refuge.
It is at 109 St and the powerline right of way path in Steinhauer. The same path in other locations also could have a safe crossing in this way too, but I am focusing on this example. There is about 140 metres between the first driveway north of the path and 29A Ave (that intersection with 29A ave needs a roundabout). This leaves plenty of space for a bend in the road, a sharper one that is, to create A right angles between the path and road, and B to make drivers slow down. I don't know whether the design speed should be 50 or 30, the slightlines are good for both speeds, given that 109 is a collector road, I think 50 is good, but it needs some refinement. Either way, the bend(s) in the road help make drivers aware that something is going on and gives them an indication that they need to control their speed and pay attention.
A good warning sign for cyclists (and pedestrians) crossing is also useful, and there should be a raised table to help with the speeds, the road should be fairly narrow, about 5.4 metres (parking isn't needed here, there aren't really any destinations that don't have their own parking lots or homes), trimming the trees as seasonal maintenance, and good visual priority. Given that there isn't too much volume and the speeds are low enough, 50 km/h, this should work well.
This goes for other situations too, some will have cyclists having the right of way, some will have motorist priority, both are used with safety and efficiency in the Netherlands. We should copy what works, regardless of where it came from.