Micropiles at Merchants Bridge, St. Louis-PPT Presentation

PPT Presentation

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The Merchants Bridge, located north of downtown St. Louis, opened in 1890 and carries an average of 32 trains per day for six major railroads and five short lines. Its aging truss spans and narrow configuration restrict it to one train at a time and limit the weight and types of railcars it can carry, creating shipping inefficiencies and raising concerns about its remaining service life.<br /><br />The overall retrofit project includes replacing the three truss spans, expanding and encasing the approach spans, and expanding and encasing the piers. Micropiles were installed to support the pier work. The site’s bedrock consists of Upper Mississippian limestone, primarily Saint Genevieve and Saint Louis formations, with reported rock quality and strength varying across the site.<br /><br />A total of 56 micropiles were installed in four phases at the four bridge piers, including work from a west-bank causeway and river platforms built over sheeting. Each pile was designed for 700 kips in compression and 200 kips in tension. Verification testing was required to demonstrate the specified tension capacity.<br /><br />Installation required careful planning around changing river levels, access, and equipment needs. Crews used platforms, boats, barges, a manlift, and crane support to reach and perform the work safely. The micropiles form part of the foundation improvements needed to strengthen and modernize this critical rail crossing.

Keywords

Merchants Bridge

St. Louis

rail bridge retrofit

micropiles

pier foundation

truss spans

bridge rehabilitation

load capacity

limestone bedrock

rail infrastructure