We here at GiraffeG4 Systems get a lot of questions about whether the GiraffeG4 can measure from a distance or do you have to be under the bridge, trestle or tree. When we started designing the GiraffeG4 we asked our engineers if preventing a "bridge strike" from a block away was possible. They explained to us it would be inaccurate and prohibitivley expensive. Plus, it wouldn't let you know if the exit side of the bridge or trestle is the "Low Clearance"side. That's why a " measure from a distance away doesn't exist.