The highway bridge at Marseilles is relative new having been completed in December of 1997. The previous bridge, a steel truss bridge, was removed in 1998. The bridge has modern features like solid guardrails, a wide sidewalk, and street lights. At the same time, the bridge is very narrow and does not have any shoulders. This would seem to make the bridge dangerous for wide loads and farm equipment. I am surprised that a modern bridge would be built that narrow.

The river has two channels at this location. The main channel of the Illinois River is on the north. There is a dam just upstream, so the water is relatively shallow but rough. Since this is not navigable, the bridge has piers in the water. The navigation traffic follows a canal that has been cut from the native rock and runs along the south side of the river. Since large tow boats use the canal, the bridge spans the entire canal width, and a hump in the bridge provides the vertical clearance needed by tow boats and river boats.

The bridge is a steel plate girder bridge. The steel beams were built up from plate steel in a fabrication yard and trucked to the site. Plate girders allow for long main spans, such as the span across the 225 foot wide canal.

This is perhaps one of the most interesting spots on the Illinois River. In this small area, there is this large bridge, a canal, a boat lock, a river dam, the milling district, two water power canals, several smaller bridges, several smaller water control gates, and the historic power plant. Even more remarkable, most of it is easy to photograph.