Old Chain of Rocks Bridge Inspection

Trailnet, Inc.


The 16 span, mile-long Old Chain of Rocks Bridge currently serves to carry a multi-use trail over the Mississippi River in North St. Louis.  The bridge was constructed in 1929 and closed to vehicular traffic in 1970 before re-opening as a trail bridge in the 1990s.  The bridge is on the National Register of Historic Places due to its affiliation with historic Rte. 66.

Horner & Shifrin completed an in-depth safety inspection of the bridge using hanging scaffold and manlifts to provide arm’s length access.  H&S was able to reach areas of the bridge that had not been inspected in decades. Inspection notes were collected in our Cloud Hosted GIS system which allowed real-time sharing of notes and photos in a web- and map-based system and detailed reporting of problems.

Our solutions to aid the project application:

  • Reduce total project cost by improving the data collection. Utilizing iPad devices engineers were able to document and photograph deficiencies directly in the field greatly reducing the amount of field time by 50% and the number of errors and omissions of data previously encountered on projects using traditional collection methods.
  • Reduce total project cost by improving the reporting process. Utilizing our cloud GIS Engineers saved over 60% in post inspection report preparation hours. Since the data and photos were combined in the GIS reports, deficiencies were much easier to combine and report.
  • Improve safety by reducing the amount of equipment carried by inspection crews. Previous projects required crews to carry and coordinate the use of notepads, cameras, pens, etc. while suspended to document deficiencies. Our solution reduced this to a single device by using the iPad for all aspects of the collection process.


Project Scope



Site Size

1 mile


St Louis, Missouri

Year Completed


Innovation. Agility.
Reliability. Horner & Shifrin.