In the case of the Thomson Road Bridge, it does not cross the main channel of the Saint Louis River. Rather, it crosses the Forbay Canal. This canal carries water from the Thomson Reservoir two miles to the east, where it then flows through pipes for another mile. The water eventually runs through giant power generating turbines before returning back to the Saint Louis River at River Mile 24.
The bridge is a very typical prestressed concrete girder bridge. It is short enough that mid-span piers are not required. As a result, the girders are supported on each end by the bridge abutments. The bridge features a reinforced concrete deck, and the modern style slanted solid guardrails. One feature of note is that the bridge has metal guardrails attached to the north end. On the south end, the bridge connects to curb and gutter. The east side of the bridge has a metal guardrail, while the west side does not. Rather it has a sidewalk with a handicap ramp leading down to the roadway. There is no guardrail to prevent someone from walking past the sidewalk and into the canal other than a small blue and white marker sign.
The photo above is looking northwest towards the east face of the Thomson Road Bridge.
