One of the worst storms I've ever experienced was in 1999 on the Ohio Turnpike westbound when I encountered a squall line. Was expecting the bad weather, because I'd heard talk about it on the Turnpike operations frequency for about thirty miles beforehand, and also got an alert on the local NWS frequency about it.
Once the squall struck, visibility suddenly decreased - not zero-zero, but not the best either. Within about twenty seconds, as I noticed the water bubbling on the top of the pavement, a little voice told me to pull over immediately. Pulled up under an overpass at MM 52 and waited for the squall to pass. Once the rain tapered off to a light, but steady, flow, I resumed driving.
Now, the reason I will ALWAYS remember the mile marker I pulled over at is because, as I passed MM 51, I encountered a serious four car crash that had just happened, most likely as the result of people encountering the squall and suddenly braking. To this day, I am still convinced that, had I not pulled over, I would have been the fifth car involved in that crash.