Saturday, 13 February 2016

Traffic light improvements

I've gone over traffic light improvements before, but it was a fairly short description. And there are some other things I want to add to these lights. Let's look at them now.

The Dutch traffic signals are considerably easier to see. This is due to their large backplate, large signals and a retroreflective stripe around the edge. In Edmonton, this would be having a 30 cm wide bulb, for each light, red green and amber, a large backplate and a yellow retroreflective stripe around the edge. This approach is actually used currently, but is uncommon. If you want an example, go drive down 170 St northbound at night at 95 Ave, or go on Gateway Boulevard at night at Whitemud Drive.

Their signals are also simpler to understand. By having a single signal for each lane, and by using a different shaped signal for turns and a completely different system for buses and LRT/trams, and having them on the nearside; this is cheaper most of the time or is the same price as our signals are, if you have an intersection with 3 lanes, a left and right turning lane and a single thru lane, there will be a single signal head for each lane.

Having the signals on the nearside does a couple functions. First, it means that drivers won't be speeding off if they notice the side road traffic lights are turning red, second, everyone will be stopping at or behind the stopping line in the correct location. IE, not in the pedestrian crossing, bicycle crossing and or the rest of the intersection, not blocking traffic. With the lights we have now, or in the UK, notably where there are advance stop lines or bike boxes as well call them in North America, intruding into these zones of the intersection is very easy and doesn't deliver an automatic consequence for doing so, that being not being able to know when the light is green and everyone honking at you from behind.

The extra backplate and the reflective stripe makes them very visible at night. I have personal experience with this from British Columbia.

This also goes for bicycle traffic lights. They are on the nearside, but they have an extra feature. Eye level lights 10 cm across. The UK recently approved those, the Dutch have had them for many years, and they just emerge naturally as a consequence of near side signals. Another thing these do well is allowing for a countdown timer to green to show. Do this in the standard light that is 30 cm across too, that lets people approaching on bike to slow down if they see the wait will only be a few seconds, to conserve energy, but knowing how long it's going to be and having reasonable waiting times makes you want to abide by the red light. And this is exactly what the Dutch have found. They take many forms, I suggest a single Arabic numeral countdown in seconds in the amber signal head, during the times that the amber light is not showing obviously.

And these measures of course can only be used where there are in fact traffic lights. And many lights can be removed successfully. Signalized pedestrian crossings switched to zebra crossings with some traffic calming like a raised table and central median refuge, a set of traffic lights changed to roundabout control, and some even just going to sign control, or complete pedestrianization or downgrade to 30 km/h zone (complete with removal of most of the traffic). So few traffic lights will in the end actually need to be like this. Some will though, but on a massively lower scale.

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