BUTLER TWP — It will be at least another month before work begins on four bridges in Butler County that will be replaced as part of the state’s rapid bridge replacement project.

Representatives with the state Department of Transportation and the Plenary Walsh Keystone Partners group had a public meeting Tuesday night at the Days Inn on Route 8 to discuss the projects.

“We expect to start the projects in June,” said Chuck Zugell, project manager for Walsh-Granite Construction, the joint venture contractor responsible for the construction work on the bridges.

PennDOT this year finalized its $899 million Rapid Bridge Replacement Project contract that will replace 558 bridges across the state in the next three years, including 11 in the county.

“We are obligated to hold a meeting 30 days prior to any work being done,” said Dan Galvin, a spokesman for Plenary Walsh.

That company will handle the design and construction work for all 558 bridges and will maintain them for 25 years.

Work on Saxonburg Boulevard over Bull Creek in Clinton Township and on Cruikshank Road over a tributary of Glade Run in Middlesex Township is slated to begin first in Butler County.

Construction on the Freeport Road bridge near Caldwell Drive over a tributary of Thorn Creek in Jefferson Township and the Zelienople bridge carrying Route 68 over Glade Run in Zelienople will begin later this summer.

Saxonburg Boulevard will be detoured along a nearly 11-mile route, while the Cruikshank Road detour will be about 5 miles.

“We’re required to stick to state roads for detours,” Galvin said. “But there will probably be smaller roads that locals are familiar with.”

Both the Caldwell Drive and Zelienople bridges will use phase construction, meaning one lane of the structures will remain open to traffic.

The projects will be completed quicker and at a lower cost than typical PennDOT work.

Galvin said grouping the bridge work together allows for the contractor to use economies of scale in each phase of design and construction, reducing the price of the projects.

The average project cost per bridge is $1.6 million, Galvin said. Under PennDOT’s standard process, the cost to build and to maintain a bridge would average more than $2 million.

Galvin said an example of the effective nature of the project starts in the design phase.

“There are five basic designs for all the bridges,” Galvin said. “That helps speed things up on the construction end.”

Plenary Walsh has yet to begin work on any of the 58 state bridges expected to be replaced this year.

It will replace 250 bridges in the state in 2016 and 2017.

Galvin said the expectation is to complete the work by the end of 2017.

“That’s a full 8 months sooner than what PennDOT required in the contract,” he said.

In the future, three bridges in the county will be replaced in 2016, while four bridges will be done in 2017.

Each bridge will have a 100-year life span.