The Bill Emerson Memorial Bridge is a cable-stayed structure which connects Missouri Routes 34 and 74 with Illinois Route 146 across the Mississippi River, BNSF Railroad, and Aquamsi Street. M&M performed the 2014 NBIS and FCM inspections of the structure, as well as an in-depth inspection of the structure’s complex features. The Complex Features inspection included 12 days of technical rope access to achieve an arm’s reach inspection of approximately 25% of the stay cables, at least one complete face of each tower above deck level, and all upper and lower anchorage locations.
M&M also evaluated the main spans’ deck (sounding, mapping, and chloride testing), modular deck joints, End Bent 1, and a shock transmission unit. Ultrasonic testing of the tie-down pins and opening the injection port caps at all lower anchorages was also performed.
M&M inspectors used directional rappelling techniques to lower themselves along the length of the selected stay cables and standard rappelling techniques to inspect the exterior faces of the towers. Technical rope access allowed M&M engineers to reach areas standard access equipment cannot reach with minimal impact to the traveling public. Inspection of the structure’s elements which were accessible without rope access, was performed with the use of an underbridge inspection unit, standard climbing, or walking the deck.
Following the inspection, M&M prepared plans, specifications and estimates for repairs to the cable guide deviators and tower pour backs, as recommended in our report. Cable guide deviators were either missing or had slid down the cables. M&M provided procedures to reinstall or install new deviators with the addition of retainer devices to keep them securely in place. M&M also provided concrete repair details for the post tensioning anchorage pour back locations on the tower faces.
|Total Project Length||3,956 feet|
|Main Span||1,150 feet|
|Total Number of Stay Cables||128|
|Lanes on Structure||4|