It's just using OpenStreetMap tags for routing, so if a bridge is impassible by foot/bike according to OSM, then it won't be able to route there. See the Verrazano-Narrows Bridge in New York as an example.
Ah okay, so it doesn't take into account automobile travel? While the bridge is certainly walkable with a heavy asterisk, the route between towns is highly inadvisable on foot (though doable on bicyclists, there's another discussion), with the rural highway sometimes not having a shoulder.
p_ing|11 months ago