[myself248]

Related, shouldn't it be possible to get data from rail signalling radios, and infer when a train is blocking a level crossing, and mark a temporary closure on that road so traffic is routed around it?

In the US at least, trains sometimes block crossings for upwards of 10 minutes, and it can be very worthwhile to drive around. Doubly so if you could know en-route and seamlessly reroute, rather than having to approach the crossing to discover the closure.

[bobthepanda]

Nearly all level crossings are required to, at the very least, trigger a signal with audible sounds and possibly gates, so you just need that same switch to update some online status.

[SoftTalker]

Many crossings in th US actually do not have any warning lights or gates, the only warning of an approaching train is the horn from the locomotive. Low-traffic (either in terms of cars or trains) crossings are often unsignaled.