A $12.4 million project that will leave the Waco Suspension Bridge closed into 2022 will start with construction of temporary supports in the Brazos River below.
The ability to make the span without mid-river support made the crossing innovative and something of a novelty when it was built 150 years ago, but the supports will be key to the process of replacing the bridge’s steel cables and decking and making improvements to its anchors, among other work. Some parking and areas around the bridge already have been blocked off, and a prerecorded ceremony broadcast Thursday morning will mark the official start of contractor Gibson and Associates’ work, expected to last between 18 and 24 months.
“This intervention should see us through the next 150 years,” Waco Senior Parks Planner Tom Balk said.
Patrick Sparks of Sparks Engineering, who performed a comprehensive analysis of the bridge in 2016, will oversee the project. He said the structure is one of the earliest surviving suspension bridges.
“Most river crossings at the time were not bridges,” Sparks said. “There were bridges over smaller streams, but at the time a lot of the large streams did not have very many. The beauty of the suspension bridge is that it spans the whole river. There didn’t have to be a mid-river pier.”
The $12.4 million cost of the renovation contract landed at more than double initial projections of $5.5 million, but the cost of the bridge’s original construction, $135,000 on the low end of estimates, wound up at more than triple the $40,000 cost projected when planning started, according to the Texas State Historical Association. It opened as a toll bridge operated by the Waco Bridge Co. on Jan. 6, 1870, and was sold to McLennan County 19 years later for $75,000. The county then sold the bridge to the city of Waco for $1 with the stipulation the city would be responsible for upkeep, according to the historical association.
Sparks said the bridge shaped local and state commerce, becoming important to cattle drives and anyone who wanted to transport goods across the Brazos River. On top of that, a suspension bridge was uncommon and considered an innovation and novelty in much of the country.
“There were very few, if any, west of the Mississippi River,” Sparks said. “When it was built, it was definitely the most important suspension bridge west of the Mississippi.”
The firm that supplied the original steel cables went on to build the Brooklyn Bridge, which opened 13 years later. Those cables were last replaced in 1914 as part of a major overhaul and have stretched imperceptibly, weakening in the century since.
The cable houses on each side of the Suspension Bridge that house the anchors for its steel cables will receive some touch-ups. On the East Waco side of the bridge the anchor houses, once tollhouses, are longer than their counterparts on the opposite bank for reasons Balk said remain unclear.
“These buildings exist because they mirror the footprint of the counterweight that is really underneath, 15 feet down,” Balk said.
Outside the anchor houses, crews will excavate 15 feet of dirt, drill through the foundation down to bedrock, and refill it with concrete.
“It’s kind of an interesting surgical process to insert some new within the old,” Balk said.
Balk said there are no good records showing the bridge’s original construction documents, but the State Historical Society of Missouri had construction documents from the 1914 overhaul, which was conducted by a Missouri company.
But before work on the anchors and replacement of the cables can start, the deck will have to be supported from below.
“The temporary supports mid-river are going to be a major engineering work of themselves,” Balk said.
He said pedestrians can expect to see a dirt ramp built underneath the bridge, where barges loaded with equipment and materials will build three supporting structures before the cables come down. Once that part is complete, workers will start working on the bridge’s span, treating the metal below the deck and replacing the wooden deck.
Steel beams, called cords, run under the deck and have the potential to trap water. Balk said workers at some point in the past cut holes into the steel beams to prevent that from happening, causing some corrosion over time. He said the renovation will address the corrosion, which had not progressed to the point of requiring the cords to be replaced.
“It’s still manageable, but it’s definitely something that caused us to pause and reflect that this project could have easily been way more expensive if those required replacement,” Balk said. “So we’re thankful, and we understand the charge is to make sure those see us through to the next century.”
The area surrounding the bridge and the walkway below it will also be closed to the public, but pedestrians will still be able to pass by the area.
University Parks Drive and Martin Luther King Jr. Park on the east end of the bridge will close for for brief periods as construction progresses, and part of Indian Spring Park on the west end will close for the duration. The river will remain open.
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