I agree with J.P.
The truck does not appear to be moving and is likely parked there for recreational purposes. The bridge is not however blocked by any means and can be driven over if one chooses to.
I'm inclined to say abandoned, too. In the aerial shot, it appears the approaches have been removed. YMMV
I would say by state terms the bridge is abandoned, and it is use at your own risk type thing. The red trucks looks like the owner is probably fishing and used the bridge as a safe parking spot, since the truck doesn't move as the street view moves.
Here is an aerial shot courtesy of Bing Maps: http://tinyurl.com/Duck-River-269
Sure enough, if you go to Google maps and use street view, there is a red pick-up truck crossing this bridge.
I drive across this bridge several times a year. It is open to vehicular traffic -- it is not marked for pedestrians only or blocked to vehicles.