Outside my university there was a fairly fast "A" road (two lanes, high speed limit, actually much narrower than a typical American street). Rather than stop traffic, there was a bridge that crossed the road. To use the bridge you needed to climb a set of stairs. Of course, people didn't use the bridge because it was inconvenient and tiring to have to take a longer route (including stairs) rather than just walk 8-10 meters across the road.

There were severe injuries or deaths every single year when students would cross the road late at night and a car would be speeding at 60+ mph. They eventually installed a puffin-style crossing, which was much better.

The solution, especially in built up areas, is to keep cars from causing problems for pedestrians rather than trying to stop pedestrians from causing problems for cars. Perhaps the cars should be relegated to a tunnel so people don't have to be near them instead.