# The Physics of the 69-Degree Intersection That Kills Cyclists in the UK

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Generally after I see an superior evaluation on the web, I simply need to make it extra awesomer. Actually, this must be everybody’s purpose on the web—both make stuff or make it extra superior.

On this case, it is a put up from Singletrack (and likewise lined by Boing Boing) taking a look at a selected crossroad in the UK that results in numerous accidents between bicycles and vehicles. One in 2011, one in 2012, and one other in 2016—all ensuing from the seeming failure of the driving force to yield to the bike owner.

In brief, the issue comes about due to the angle of the intersection (it isn’t perpendicular) and the angle of the blind spot within the automotive from its entrance pillar.

Here is what I need to do. I need to make an animation in python that reveals the movement of each the automotive and the placement of the blind spot (they name it a pillar shadow) on the opposite highway. As soon as I mannequin the movement of the blind spot, I may discover its velocity. Even higher, after construct a mannequin it will likely be tremendous trivial (which is manner simpler than trivial) to vary the placement of the blind spot or the angle of the intersection.

Earlier than getting began, I want some particulars. In accordance with the Singletack put up, the 2 roads cross at 69°. Their put up additionally reveals a picture of automotive with its pillar shadow. Utilizing Tracker Video Evaluation I can simply measure the angle between the entrance of the automotive and each the main and trailing fringe of the shadow (19.four° to 27.1°). Simply to be clear, here’s a primary diagram of that shadow. Word that that is within the UK, so the drivers are on the flawed facet of the automotive.