Sunday, 14 February 2016

Median refuges

Edmonton has a very noticeable lack of pedestrian crossing median refuges, and as far as I know, none for cyclists. On the opposite side of the spectrum, the UK is well known throughout pedestrian and walkability and usually cycling advocates for how many pedestrian refuges it has at traffic light controlled intersections, usually with separate crossing, each controlled by separate lights for each direction. If you want to know how that works, look at this video: Usually they are staggered, this is one of the "nice" exceptions. And often they come with guardrails, something which even Texans don't have.

There are several advantages to pedestrian (and also bicycle) refuges between the two streams of traffic when you can add one in. First, it reduces the corner radii for motor vehicles, they tend to go slower. Secondly, strategic placement of these can make drivers in dedicated turning lanes make that turn. here is an example:,6.5220347,3a,75y,349.29h,62.91t/data=!3m6!1e1!3m4!1s6Os8S6f2YpF2upZ_9-ywwg!2e0!7i13312!8i6656?hl=en. Thus, self enforcing rules. It makes the road look narrower and sometimes be narrower, making speeds lower. And of course, it creates safe places for cyclists and pedestrians to be in, most of the time. And finally, they can help break up crossings or movements into easier to preform steps. At a zebra crossing, you can check for traffic in one direction at a time if you have a central median. Same with other intersections without traffic lights but having space between the directions of traffic.

Let's go over each one to demonstrate what use they are.

Reducing corner radii with a central median means influencing the left turn for the most part, though in the case of larger vehicles that tend to swing to the left for right turns, this can also apply to the right turns for them. It also means that you are less likely to have the ability to hit cyclists/pedestrians because there is a curb protecting them for greater distances. You also are more likely to be set back from the intersection if you have that median, meaning that a vehicle will turn 90 degrees or very close to it when they at at the crossing. This also applies for the left turn.

The second is not often thought of, but if there isn't a way to make you make a turn if you are in a dedicated turning lane, then you can never be sure about whether they will make the turn or not. It relies on trust. And this uncertainty reduces the capacity of the intersection because you will be using fewer free opportunities you might otherwise be using. And when people are given incentives to do things, they will more often than not, do those things. And if roads look narrower, research considering average speed before and after shows that narrower lanes, or at least when it looks like there are narrower lanes, drivers tend to slow down more.

The safe place to be in depends on design. With a wide enough median, it can be quite OK. For a narrower one, it's better than nothing but can't be a suitable place if you have to wait for other traffic to go first, like at a traffic light. A minimum should be 2.4 metres, the length of one bakfiets, for a bicycle, and 1.8 metres minimum for a pedestrian, someone pushing a stroller, and 3 metres or more preferable minimum, maybe 4-6 metres standard. And there also needs to be the curbs on either side that protect you when waiting. Guardrails are not needed, in fact they are detrimental. You can see videos of cyclists in London being forced between a guardrail and a truck, a combination which is never good. The width plus the curbs and preferably some plants like a tree that has a clear truck for a few metres above the ground, some flowers, low hedges, and similar will make it feel pleasant to use the median. Not that you want to stay there for long. Just that concrete and metal is not as inviting.

Here is an example of how such a refuge could be used. Say the walk light at a traffic light just turned to a flashing don't walk, and you ignore it and cross anyway. You might only have time to reach the middle of the road. If you had crossed on the walk light you would be assured the ability to cross in one go. Note that cyclists are always fast enough to cross an entire arm in a single stage, and sometimes 2 arms depending on the layout. It could also be used to let pedestrians have more time to cross. For example when a protected left turn is happening, you can let pedestrians have a bit more time to cross the half of the road that still has yet to be crossed.

And the easier to preform steps in fewer easier stages is probably the most important. Britain overdoes this with pedestrian refuges at traffic lights by having separate lights on different cycles not coordinated with each other, often with a stagger. It really slows pedestrians down. At a zebra crossing, you can look in one direction at a time, as I said before, and you can make sure that traffic is not coming in only 1 direction at a time, or at least they are stopping for you one direction at a time. And when the traffic lights go to flashing amber mode at night or whenever else there is low enough volumes of motor traffic for this to work or the lights fail altogether for whatever reason, the intersection can still be made safe by having these median refuges to ensure they would work even without the lights to the greatest possible extent. You can check for other traffic behaving correctly, or not behaving correctly, who is approaching, from where, and you can do this in fewer easier to follow steps.

It is a major reason why so many Dutch intersections are safe, roundabouts especially (assuming they aren't the annular kind). And even among the kind where there are simple crossings with one road having the right of way over another that is busy enough to have a median refuge, they can be made dramatically safer with this.

Now would be a good time to adopt it? Don't you agree?

No comments:

Post a Comment

Thanks for commenting