This is a double lane crossroads. The train comes from above and decides it might be the best idea to make a looping in the crossroads before continuing downwards. This however insteadly deadlocks the train. Note that the train would have enough options to go a different way, but it stubbornly keeps waiting for itself instead of just picking another path.
This behavior is very unfortunate and happens sometimes. When other trains pass, sometimes the train will reroute to another path and will get unstuck. This shows that it seems to be indeed possible even with the current algorithm to simply pick another path.
Possible fix: Try to reroute when a train encounters it is waiting for itself.
