[Benji_San]

Seems really cheap tho. I wonder what the Medical cost + opportunity costs for avoiding e.g. 50% of crashes in the junction would be over e.g. 10 years. Probably a lot more than 100k for fixing the junction.

[Gibbon1]

I think California DOT tracks collisions and has at least some sort of algorithm to decide when to make changes.

Scary looking link to guidelines.

https://fhwaapps.fhwa.dot.gov/hsipp/Attachments/aa343eab-2cb...

That said I looked at the intersection on google maps. Here it would have have had a stop sign at least or fixed decades ago.