They're installing electronic alert systems at train crossings to replace noisy train horns. Why couldn't a similar idea work for crosswalks?
How practical is that, especially for unmarked crosswalks?
With everything getting connected to the internet it would be very practical for signalized crosswalks. Vehicle to everything communication is nothing short of a revolution
How practical is that for unmarked crosswalks?
It's missing the point anyway, because |kernals12| is mistaken about what jaywalking actually means.
Generally (going by the UVC)...
1. Pedestrians are allowed to cross the street anywhere they please–crosswalk or not–with very few exceptions. Notably, crossing the street outside of a crosswalk is prohibited within one block of a signalized intersection or at a point where there exists a pedestrian bridge or tunnel. That's it. Everywhere else is perfectly legal.
2. Where there is a crosswalk–marked or unmarked–pedestrians may cross the street whether there is traffic coming or not, as long as they don't suddenly jump right out in front of traffic is "so close as to constitute an immediate hazard".
3. Where there is no crosswalk, pedestrians are required to yield to all cross traffic.
Putting this all together, then: There is an infinite number of places where pedestrians are legally permitted to cross the street, but at which they are required to first yield to cross traffic. I therefore don't think it's a good idea to make it more difficult for people to tell if cars are coming.