Private railroad companies will rebuild a 128-year-old railroad bridge that spans the Mississippi River north of downtown St. Louis despite failing to secure federal funding that would help pay for the project.

The Terminal Railroad Association of St. Louis announced Tuesday that it will work with Bank of America Merrill Lynch in St. Louis to finance the $172-million project. The project had sought a federal grant that could have covered as much as a third of its cost. Chicago-based Walsh Construction will begin work on the four-year project this fall, according to association representatives.

Without renovation, the bridge would be usable for, at most, another 10 years, according to regional railroad experts.

“It simply wasn’t anything that we could continue to delay,” said Asim Raza, chief legal officer and director of corporate affairs for the association.

The bridge is a crucial part of St. Louis’ freight system, according to Mary Lamie, executive director of the St. Louis Regional Freightway. Lamie said that a strong rail system supports the barge, trucking and air-freight industries here because many products transfer from one mode of transportation to another.

“If one of those modes are significantly impacted and impaired, it impacts the cost for all of the modes of transportation.”

Why the bridge matters regionally

Credit Brian Heffernan Merchants Bridge, one of two rail bridges used for freight in the St. Louis region, is located north of downtown St. Louis.

Merchants Bridge is one of two rail bridges used for freight in the St. Louis region. Both are operated by the Terminal Railroad Association, which is owned by five freight railroad companies. The St. Louis Regional Freightway designated the Merchants Bridge renovation as the region’s number-one infrastructure priority in November.

The U.S. Department of Transportation’s Bureau of Transportation Statistics has projected that the amount of freight moved by rail will grow by 24 percent between 2015 and 2045. And the cumulative amount of freight shipped by all modes of transportation will increase by 40 percent during that same period, according to bureau predictions.

Updating the Merchants Bridge will poise St. Louis to profit from that growth, rather than trail behind, Raza said.

If the bridge weren’t updated, some railroad companies would reroute around St. Louis. Those reroutes could take some trains more than 100 miles outside the area, according to Raza.

“That type of activity, the economics of it, jobs, would all go to different parts of the country,” Raza said. “So by doing this, what we’re doing is we’re allowing St. Louis to remain a major part of the national infrastructure.”

Renovation plans

The rebuild would replace the bridge’s three main spans; improve its functionality during earthquakes; allow two trains to cross at once; and smooth the Illinois-side approach to the bridge.

Those changes will improve the region’s existing ability to move freight, Raza said. “It’s going to reduce idle times, costs and expenses associated with moving freight through this part of the region.”

Currently, only one train can cross the bridge at a time. Though the bridge is rated for speeds of up to 20 mph, trains may have to idle while another vehicle crosses, then proceed at a slower speed.

Lamie noted that the renovated bridge will also benefit the public because Amtrak passenger trains use the river crossing. The bridge connects to six major freight railroads and five shorter carrier railroads, according to the owners.

Follow Kae on Twitter: @kmaepetrin