Flying through the sky: Building the Beaver River Bridge replacement

It’s normal work for the Pennsylvania Turnpike to replace a bridge, work in a river, build a new road, widen a highway, relocate a stream, tunnel under the turnpike or revamp an interchange.

Replacing the Beaver River Bridge, 12 miles east of the Ohio border at the Route 18 interchange in Beaver County, is all that and more wrapped into one project.

The five-year, $294 million project is part of the turnpike’s ongoing plans to widen the toll road from two lanes in each direction to three lanes from Ohio to New Jersey. Now nearly 2½ years into the project, six of the eight piers for the new bridge stand nearly 200 feet from the ground in the the Beaver River valley.

But it took quite a bit of work to get there.

“When we first started, this was a mudhole,” said Josh Farley, senior turnpike engineer serving as project manager, said as he stood on the temporary bank during a tour last week. “This was a major early challenge.

“Our first couple of years was roadway work. Access to the river was a major, major challenge. [The contractor] had to do a very big project just to get to the main project.”

Preparation for the project actually dates back more than 12 years with the turnpike doing early-action projects to replace two railroad bridges and create more room for the new highway.

The current project covers 2 miles, from mile posts 12 to 14, but for years the biggest challenge for designers was how to replace the bridge across the Beaver River without closing the turnpike during construction.

They settled on the option to build the new bridge next to the existing one, eliminating the extensive toll plaza because the agency has switched to all-electronic tolling and moving the whole roadway about 150 feet north to meet the new bridge. The distance from the middle of the existing bridge to the middle of the eastbound section of the new one will be 150 feet.

Additionally, designers have raised the new configuration by about 25 feet to make for a smoother ride and a better connection at Route 18.

Choosing that design created other situations to deal with.

For example, crews had to bore a 100-inch tunnel under one section of the turnpike to divert a stream in the construction area.

And they have to deal with building in and around the river.

“Building on the river is a little challenging,” Farley understated.

Working on the river

Access to the Beaver River in that area was, in Farley’s words, “pretty close to impossible” because it is shallow, has no banks and the hillsides down to the river were covered with brush, trees and dirt. How much dirt: about 2 million cubic yards, each the size of a small refrigerator.

Contractor S&B USA Construction would have to clear the banks and build a windy new access road to get to the construction site.

At the edge of the river, crews had to create temporary flat work areas that could accommodate eight to 10 huge cranes at a time. The cranes would be moved to the site by barge and offloaded to the staging area.

That limited access to the site also affected the type of construction for the bridge. For many projects, the turnpike uses long steel or precast concrete beams between bridge supports, but the frequent curves in the access road and the shallow river made it impossible to deliver those beams to the site because they would have been so long and heavy.

Instead, the design calls for eight piers to be built in the river and the hillsides beside it, four on the eastbound side and four westbound. From there, crews will follow a painstaking process that involves working on the tops of the piers for months building segments 15 feet at a time to close the gaps between the piers.

Farley said that style of construction – called balanced cantilever construction – isn’t something the agency uses every day.

“It’s a little out of our wheelhouse, but we have access to the experts to make it work,” he said. The turnpike built its first bridge using this kind of segmental construction in 2007 at the Susquehanna Bridge between Dauphin and York counties.

Piers and construction tables

So far, crews have installed six of the eight piers for the side-by-side bridges, and the foundations for the other two are ready and waiting. Again, this was a challenging chore.

The process starts with building the foundation, in this case 66 feet in diameter. Each foundation has 11 caissons drilled 130 feet into the bedrock below the surface, then the tubes are filled with grout.

For the piers in the river, crews first have to build a cofferdam, a water-tight structure to create a dry workplace to drill the caissons.

That strong foundation is the key to the rest of the structure’s stability, causing Farley to wax philosophically, “You have to be one with the earth before you can fly through the sky.” Asked if that was an old engineering axiom or something from a mentor, he smiled and said, “It just kind of came to me.”

With the foundation set, huge forms for the pier are built on top and filled with concrete a section at a time until they reach the desired height, then the wings are added on the sides to support the bridge structure, and a work platform is built on top. From the bottom of the subterranean caissons to the top of the platform is about 375 feet.

With the piers in place, a crew of 20 to 40 workers can install 90-by-30-foot construction tables on the top and down the sides about 30 feet, creating two work levels. To pour the table, crews use wetter-than-normal concrete so it flows into all the crevices on the table and add chemicals to help it cure quicker.

From these tables, they can build out north and south in 15-foot segments, which they do at the same time to keep an equal amount of weight on each side to maintain the balance of the pier.

At the end of each segment, a steel strand is used to link to the next one and tightened to create tension. After a finished segment sets for two days or more, crews use a hydraulic jack to move the form out another 15 feet for the next segment.

The distance from one pier to the next is 385 feet, and the goal is for the segments to meet within 5 feet of each other in the middle. This is a critical element, and surveyors are “constantly” reviewing the segments to make sure they are level with each other and won’t be mismatched when they get to the middle, Farley said.

When all of the segments are between the piers on one side of the project, there will be a special pouring of concrete to seal the connections between them. For the complete bridge, crews will install 88 of those sections on the east side, 88 on the west.

Farley said this type of construction does have one major advantage: There are no expansion joints on the bridge to allow for swelling and contracting in changing weather conditions. Those joints are elements that naturally wear out over the years and require costly regular maintenance.

With the segmental construction, the bridge may sway slightly in changing weather conditions but not enough that motorists will notice it.

Farley and Chuck Grabner, project manager for S&B USA, said working on platforms 200 feet in the air comes with its own problems. For example, although the Beaver River valley is less than a half-mile wide in most areas, the weather can be different from one side of the river to the other.

And it’s not a pleasant place to work during winter weather.

“Over the past few months, we’ve had some frigid days up there where they had to go to the middle for some protection from the elements,” Farley said.

Workers get to the top climbing scaffolding built on one side or riding special lifts. Cranes with booms 180 feet long – some of the longest in the industry – lift supplies to waiting workers.

Getting concrete to the platforms is another matter.

The concrete supplier uses high-pressure pumps – 300 bar pressure in industry terms – to push the concrete into hoses attached to the side of the piers and force it to the top. On top, crews use another compressor to push it out onto the segments.

For the entire project, the turnpike expects to use 50,000 cubic yards of concrete, enough to fill more than 16 Olympic-size swimming pools.

At the current pace, the contractor should finish the westbound side of the project by the end of the construction season, the eastbound side by the end of 2026. The full project, which includes rebuilding a portion of Route 18 (Big Beaver Boulevard) to accommodate a free-flowing interchange like other interstate highways, should be fully functional in mid-2027 and completed by the end of that year.

Farley said this is one of the longest-lasting projects that he has worked on, and it takes a special effort for the agency and contractors to meet challenges together.

“The turnpike tells us this is our project — not your project, not your project, not my project,” he said. “We pretty intentionally set it up that way because we know it’s a long project. It’s hugely important for this to be successful for all of us to have that attitude.”