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How this simple intersection creates dangerous blind spots

posted by Jason Kottke   Jan 09, 2018

I’m a (very) amateur traffic enthusiast (see here and here for recent posts) who is fascinated by how different kinds of intersections are better than others for safety, traffic flow rates, etc. There’s a fairly normal-looking four-way intersection near Southampton that’s been the site of the deaths of two cyclists, and it turns out that geometry likely played a factor. The road is oriented such that a cyclist and a motorist approaching the intersection on the crossing roads could possibly not see each other until they collided.

Intersection Geometry

Ipley Cross is constructed in such a way that not only is it possible for a careless driver to drive straight into a cyclist without seeing them until a fraction of a second before impact, but under the exact same circumstances it is also possible for that cyclist not to see the car that hits them until the same moment.

If anyone were to take a highway engineer to a wide open space and ask them to design a junction which would readily enable two road users to collide with neither of them ever seeing each other, I doubt any would be able to manage it.

Yet this is precisely what exists.

When I watch other people drive, I’m amazed at how many of them don’t take the time to look around the pillar in the front of the car…it’s such a massive blind spot. I don’t know if it’s all the driving in NYC — the right pillar perfectly obscures pedestrians stepping off the curb on a right turn — but I always check that blind spot. And a related tip for pedestrians: if you can’t see a driver’s eyes, they might not be able to see you.