Tuesday, 26 January 2016

Minor side streets

A lot of people, especially vehicular cyclists and city planners, tend to say that sidepaths are dangerous at minor side streets, more specifically sign controlled intersections where the roadway that is given the right of way has a bicycling path on one side or the other side or both and there is a roadway that is facing a yield or stop sign and intersects with the path.

Well, it all depends on the design. A badly designed cycle track is dangerous, but a well designed one can be the thing that encourages thousands of people to ride on it every day for all the trips they need to make.

Let's start with where these side street crossings (and how bike lanes fit in) are used and how they work.

They are generally used at the intersections between an access road and a distributor road, though sometimes distributor roads and another distributor road intersecting will have them in lieu of a roundabout or traffic light, and sometimes at the intersection of a through road and access road, though that should be rare, and often at a driveway/business access and distributor roads.

Gas stations tend to have the cycle path bypassing it in such a way that the cross section would look like the through road/distributor road in the centre, the bicycle path and sidewalk on the outskirts and the gas station in the middle. There is an access from the cycle path to the gas station though because their might be employees who could commute by bike. This design can also be used for other types of related businesses. It avoids conflicts well.

Minor side streets that are too frequent should have a fietsstraat on either side of the main roadway, limited to 30 or 60 km/h for urban and rural areas respectively. This avoids conflicts at high speed. Mark Wagenbuur made a blog post about how this works: https://bicycledutch.wordpress.com/2012/05/21/dutch-service-streets-and-cycling/.

A further way to reduce this right hook problem (and left hook) is to downgrade the road. This is not always possible, but it can be done in many places. Even if you can't downgrade a through road into an access road, you can often make it a distributor road, at a lower speed and with lower volumes and generally with more space to allow bend outs and lowered corner radii. But getting roads with destinations on it downgraded to an access road helps a lot.

And the best way to deal with the right hook and left hook problem is to remove the problem altogether. Close off the road access if you can (to cars). Especially in the older parts of Edmonton, on the grid system there are far too many minor side streets intersecting with main roads. A few hundred extra metres for a car is practically nothing, just a few seconds. Even a kilometre is not a long distance in a car. A minute or so perhaps.

So what happens at remaining minor side street intersections?

If the road is an access road that serves as the main access to the neighourhood, then a roundabout can be an attractive option if the volume from the access road is high enough to compete with the main road traffic. Design as a fairly normal roundabout, except that usually if the volume is low enough, then the cycle path will merge back into regular traffic. It would be like how a freeway ramp merges with the main flow of traffic, except on a scale more like 15 metres rather than 150 metres of length.

The other option is to have a right of way intersection. The side street faces a yield (and very occasionally a stop sign) sign and a row of sharks' teeth to indicate who has the right of way over whom. The colour of the cycle path is red, to highlight the conflict, with dyed asphalt or concrete, and there will be elephants feet markings (large square markings flanking the crossing). But the physical design is even more important. There needs to be pretty low corner radii to assure low turning speeds. A truck apron can help with this, making the curve smaller for passenger vehicles and vans and larger for larger vehicles. Of course the really big vehicles should be prohibited where possible. No semis off the through roads, and only vehicles less than 3.5 metric tonnes into the 30 km/h zone. A raised table also helps out too. The elevation incline will vary depending on the intent of the access, lower and gentler for busier side roads, like a distributor road being the side street, more like a rolled curb that you find on a driveway access for the 30 km/h roads and for driveways, both business accesses and home access. For pedestrians, on business accesses, driveways and 30 km/h access roads, the sidewalk should continue as normal. Otherwise it is designed like a zebra crossing over the side road.

But probably the most important part of this is that wherever possible, there is the space for a car/van to turn and face the cycle path at as close to a right angle as possible and to the greatest possible extent, be out of the way of other traffic. This is about 5-6 metres or so, and some can be wider. The more space, the better. The tight corner radii slow the speeds and make it very obvious who is doing what when, the distance creates the visibility and the ability for drivers to deal with as few things as possible at a time. There will be some exceptions, but for the most part, there is enough space to put at least about 1.5 metres between cycle path and roadway, which is still better, and does create the space for a car to turn slightly, making it obvious to the cyclists at least if you are doing something.

Also important is creating space in the middle of the road as much as possible to break up the crossing into as few steps as possible. And it also creates the space for cyclists and pedestrians to break up crossings in this way as well, with pedestrians having a zebra crossing, sometimes with amber flashers, and cyclists having a priority crossing sometimes if the sightlines are good if the route is a major route for cyclists, otherwise there will be a yield sign facing them. If the volume is right, that shouldn't be a problem.

The volume and will determine the specifics, but there are a few things I know. I got a copy of the Alta Protected intersection model, which if you remove the traffic lights and put in some signs, given the right volume and speed, will work well without lights, and it says that 80% of motor vehicles will yield to cyclists and pedestrians when turning right at 10 miles per hour, which is ~15 km/h. And this is the relatively wide corner of a protected intersection and a 3 metre turning radius and just paint and signs to ask drivers to yield. Given the walking pace you need to go over the gateway style of access road/driveway style of crossing with a raised table, tighter curves and a continuous sidewalk, pretty much every car driver and van will yield. And even if they don't the speed is slow enough that a pedestrian and cyclist can stop in time, and if someone gets hit, they are likely to remain uninjured at walking pace and a much smaller chance of injury and almost no deaths if any at all at 15 km/h.

The right and left hook "problem" really isn't a problem given good design. With a good design, it makes it clear who should go first and what behavior is naturally suggested and enforced at a location like this: https://www.google.ca/maps/@53.4247239,-113.5145274,3a,49.5y,240.75h,77.59t/data=!3m7!1e1!3m5!1scIaDbevDL7GGH5HcwniVXQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3DcIaDbevDL7GGH5HcwniVXQ%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D338.30493%26pitch%3D0!7i13312!8i6656?hl=en verses this: https://www.google.ca/maps/@51.7087494,5.3294625,3a,90y,206.96h,80.18t/data=!3m7!1e1!3m5!1sMWg6q6tTVyrU2A73jl4ozg!2e0!6s%2F%2Fgeo0.ggpht.com%2Fcbk%3Fpanoid%3DMWg6q6tTVyrU2A73jl4ozg%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D315.44757%26pitch%3D0!7i13312!8i6656?hl=en and especially this: https://www.google.ca/maps/@52.3748622,4.8720517,3a,50y,214.48h,75.7t/data=!3m7!1e1!3m5!1s8cBuQjF6dMM-tisYJny_Zg!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3D8cBuQjF6dMM-tisYJny_Zg%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D303.87161%26pitch%3D0!7i13312!8i6656?hl=en.

Bike lanes update

For the bike lane part of the equation, they can be used with success, but it depends on low speeds and low volumes, no more than 50 km/h and not more than a few thousand vpd. The side road should be using the continuous sidewalk design as much as possible, and there should be a continuous cycle lane, as in, elephants feet markings, red asphalt, and the yield sign faces the side road. If possible, it should transition into a cycle track before the intersection. On the side road, it should be low volume as well, and preferably having things like a median refuge for cyclists and motor vehicles, so that you can do as few things at a time as much as possible. They can work, but under very limited circumstances and they should be uncommon. 

No comments:

Post a Comment

Thanks for commenting