This is the bridge over the Gasconade River. That barrier is all of two feet high and you can ride to a similar barrier on the other side. When I got there I noticed pedestrians on the bridge (there's a swimming hole nearby) and there are no notices telling peds/riders to stay off. If the state really wanted that they would have put chain link fence up etc., but it is very much closed to motor vehicles.
i checked this out because several times I've come across road closures where a pedestrian or cyclist could easily get through. At worst I would have had a six mile round trip to satisfy my curiosity.