Flyers warning residents about the coming Commercial Street Bridge replacement — and the shutdown of Parkway East — have landed in nearby mailboxes, setting the stage for the disruption ahead.

“PLAN AHEAD! 25-DAY CLOSURE,” the flyer begins in all-caps.

Parkway East, also known as Interstate 376, will close between the Squirrel Hill Tunnel and Edgewood/Swissvale Exit 77 from July 10 to Aug. 3. PennDOT is spending $95 million to replace the Commercial Street Bridge, part of the highway just outside the Squirrel Hill Tunnel. The 846-foot-long and 85-foot-tall bridge is 75 years old and in poor condition.

A notation on the flyer, however, notes that the closure dates are tentative.

“These dates are subject to change, as unforeseen issues may arise during the project,” the notice says.

Factors that could impact the timeline include weather, equipment and personnel availability, said Yasmeen Manyisha, safety press officer at PennDOT. The contractor has an incentive to meet the deadlines — and a disincentive if the project goes beyond the target date, though.

“While we are fully expecting to meet our timelines for this project, it’s important to remember that every project requires a bit of flexibility,” Manyisha told TribLive. “These dates could shift slightly due to factors beyond our control.”

The flyer, mailed by PennDOT, includes a large map of the affected area. It shows the road closure in red, alongside detours in purple, pink and blue. There is also a recommended bike route to avoid the area on the map as well.

The other side of the flyer starts with a warning: “PLAN YOUR ROUTE NOW!”

PennDOT said travelers should “expect heavy delays,” advising people to work from home or use alternate routes. Travelers should also carpool with friends or use Pittsburgh Regional Transit and Westmoreland Transit services to “reduce closure traffic.”

“Detour routes will experience significant congestion,” the flyer says.

The most current information can be found at pa.gov/CommercialStBridge.

The project will close the section of Parkway East at 9 p.m. on July 10.

In the 25-day project, workers will set up a perimeter 800 feet in each direction around the Commercial Street Bridge to demolish it with explosives and hydraulic hammers. In the closing days, they will slide the new bridge into place using a greased rail system and dozens of jacks.

Workers performed multiple test runs of the sliding maneuver last Thursday and Friday, moving the new bridge one foot during each test. The bridge will slide around 100 feet in total next month.

Staff writer Adam Babetski contributed.