Princeton’s covered bridge was damaged: What other low clearances exist in the Illinois Valley?

The Historic Red Covered Bridge, north of Princeton, is one of the most iconic landmarks in the Illinois Valley. The bridge spans 149 feet over Big Bureau Creek. The clearance of the bridge was 11 feet, 10 inches before it was struck by a semi truck on Nov. 16, causing extensive damage to the structure.

In the wake of the incident, it led to the question of what other structures have low clearances across La Salle, Bureau and Putnam counties, and what other structures are at risk for this kind of crash?

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An aerial view of the Captain Swift bridge on Monday, Nov. 27, 2023, near Princeton. The bridge has a 16 foot, 3 inch vertical clearance. The bridge was built in 2006 and is made entirely of wood. It's the only two-lane covered bridge in Illinois. (Scott Anderson)

The Red Covered Bridge’s sister, the Captain Swift Bridge, has a vertical clearance of 16 feet, 3 inches. It is located on 1600 North Avenue, just west of Princeton. It was built in 2006.

The train viaduct in Mendota located near the intersection of Fourth and Sixth avenues is likely the smallest clearance overpass in the Illinois Valley, at just 9 feet tall. A number of box trucks and other high-profile vehicles have hit the viaduct numerous times because of its short height.

The Ottawa Rail Bridge that spans across the Illinois River is second to Mendota’s viaduct with a measurement of 9 feet, 6 inches. Motorists can drive underneath it on the south end at Allen Park.

In Illinois, the maximum legal, vertical height dimensions for a semi truck is 13 feet, 6 inches with a width of 8 feet, 6 inches, according to the Illinois Department of Transportation.

A majority of bridges and overpasses will have the clearance height posted on the bridge or list it on a warning sign before it. When companies exceed those measurements, they must obtain a Special Hauling Vehicle Permit from the Office of the Illinois Secretary of State. Truck drivers are required to follow special truck routes and obey weight limits posed on roadways.

“The public can find vertical clearance dimensions on most structures in the Illinois Valley listed on the Illinois Department of Transportation’s Getting Around Illinois website,” said Junior Senat, district operations engineer with IDOT Region 2 in Ottawa. “Once there, click on Commercial Maps, Designated Truck Routes or Obstructions and Restrictions Maps. Turn on the layer for vertical clearance.”

It’s interesting to know most of the low vertical clearance structures in the Illinois Valley are train bridges and are not located on major truck routes.

Preserving overhead infrastructure relies on careful planning and knowing what clearances motorists can encounter in their travels, according to IDOT. An attached gallery of photos shows a visual of those low-clearance bridges and overpasses around the Illinois Valley that motorists drive under every day. Look up and read the height.