Narrow bridges or bridges with weight limits.

We use Copilot RV app on our iphone. You input your rig height and weight and it will route you around any problem areas. You can set it to route quickest (usually interstate) or shortest, which will take you on other roads. It will also give you a warning if you override the routing. We use interstate highways, US highways and state roads. Most of those are used by truckers so we haven't had any problems using that criteria. We follow any posted truck route signs. We do not take our RV on county roads unless necessary. We don't drive it in major cities. We park our RV outside the city and drive our toad sightseeing. Don't know of any GPS that warns of narrow bridges. We just watch for signs and slow down. Also other considerations: tunnels with propane restrictions, RV restrictions on New York Parkways.