Why this British crossroads was so dangerous

Tom Scott3 HN recommenders · 2020–2025
3.9M views · explainer · evergreen · Uploaded 2020-04-27

Tom Scott explains why Ipley Cross in England's New Forest was one of Britain's most dangerous junctions. The angled crossroads lets a car's A-pillar hide approaching traffic and cyclists because there is no relative motion in the driver's view.

Used as the go-to visual demonstration of A-pillar blind spots and badly designed junctions.

Watch on YouTube

10 comments from Hacker News

@sitharus2020 · in “Collision Course: a type of road junction that is dangerous for cyclists (2018)”

The Tom Scott video has a good animation on this: [VIDEO] Because of the layout of the junction the cars are actually approaching from behind the cyclists.

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@whymauri2021 · in “In 2019 40% of San Francisco traffic fatalities are from left turns”

For a particularly dramatic example of this, Tom Scott made a video about an intersection in the UK that's poorly designed for visibility: [VIDEO]

@matsemann2021 · in “In 2019 40% of San Francisco traffic fatalities are from left turns”

Sounds to me like cars shouldn't be allowed to drive where pedestrians travel, if they can't really avoid driving people over. Edit: This Tom Scott video shows how a cyclist can be perfectly occluded by the A-pillar while both are moving [VIDEO]

@kibwen2021 · in “In 2019 40% of San Francisco traffic fatalities are from left turns”

> The angles we were converging at meant that he basically disappeared into the background because there was no relative motion. This effect is demonstrated in this video about a particularly dangerous crossing in the UK: [VIDEO]

@zinekeller2022 · in “Tesla to recall vehicles that may disobey stop signs”

The Wired reporting is based on Bez's article on Singletrack (as stated): [LINK] Tom Scott made a good complementary video about this: [VIDEO] It's already fixed just last month: [LINK] and [LINK]

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@antiterra2022 · in “Blindspots on SUVs, vans, and pickups are bad for pedestrian health”

The blind spots in the article are from the A pillar, which isn’t addressed by rear view mirrors. The momentum would tend toward this being solved by sensors/computer vision, but maybe chip shortages have curtailed that. Tom Scott presented an interesting example of A pillar blind spots causing problems: [VIDEO]

@DoughnutHole2022 · in “Effects of large vehicles on pedestrian and pedal-cyclist injury severity”

Tom Scott has a good video for anyone looking for a visual of this phenomenon: [VIDEO] He shows off a rural (and thankfully now fixed) crossroads in the UK with seemingly great visibility and an unusually high rate of cyclist fatalities - the roads are at such an angle that any reckless driving speed can align with a reasonable cycling speed such that the driver's door pillar can block visibility of a cyclist with right of way right up to the point of impact - and it's compounded by the fact that the car is necessarily approaching from behind the cyclist, so a passing cyclist will be unaware of the danger possibly until they get hit. Of course if drivers in the area actually followed the stop signs no one would get hit - but if you watch the video in a five minute period genuinely only about half of the cars passing through actually come to a complete stop at the stop sign. You need more than signage and quietly hoping that people to do the right thing.

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@notatoad2024 · in “California debuts 'turbo roundabout' to fix intersection near Bay Area”

this article seems to have some actual pictures: [LINK] the previous configuration as shown on the satellite image looks a lot like the intersection Tom Scott made a video about, where the intersecting road is angled to keep cross-traffic hidden behind a car's a-pillar. [VIDEO]

@bombcar2024 · in “Higher vehicle hoods significantly increase pedestrian deaths, study finds”

See [VIDEO] for an example. One of the advantages of raking the front windshield for aerodynamics is changing the geometry for the A pillar to be more sideways instead of vertical, allowing a bit more hope of seeing something.

@pfdietz2025 · in “Making an intersection unsafe for pedestrians to save seconds for drivers”

Example of an insideously unsafe intersection that was changed to make it safer (for bike riders): [VIDEO] How it was fixed: [LINK]