I've now finished the railway crossing over the crossover; for a long period of time this was a chasm of railway tracks that would swallow entire cars whole! However all good things must come to an end and so I have patched up the holes. Always fun trying to squeeze bits of road between moving turnout blades!
The crossing is just an elaborate collection of carefully trimmed pieces of balsa, painted and weathered with powders to match the rest of the road.
I've also taken the chance to install some cross-bucks. Thanks to the wonders of the internet, these days even the Federal Highway Administration have the exact dimensions of railway crossing signs online. Saved me having to visit a real railway I guess.