PennDOT’s $95 million Commercial Street Bridge replacement project is now underway — sort of.

Commercial Street closed Thursday at 6 a.m. between Whipple Street and Summerset Drive until 4 p.m. as workers perform a trial run of the sliding maneuver they’ll use next month to move the new bridge into place.

The Parkway East itself will close on July 10 for the main phase of the project, which will take 25 days.

Local leaders gathered under the massive bridge for the start of the project.

PennDOT Secretary Mike Carroll said the decision to shut down the bridge was “not one we took lightly,” but it was preferable to a prolonged series of temporary shutdowns.

“For me, it was not a close call,” he said. “Twenty-five days of inconvenience (versus) four years… I’ll take the 25 days.”

Pittsburgh Regional Transit CEO Katharine Kelleman had a simple message for commuters during the closure: “Don’t drive.”

“It’s going to be a mess — I don’t think I can overstate that,” she said.

Kelleman encouraged commuters to instead utilize the transit agency’s buses, which will remain on normal service during construction and may even expand operations as needed.

PennDOT District 11 Executive Jason Zang said PennDOT will set up a 24/7 livestream of the bridge during construction so Pittsburghers can check in on its progress.

However, he warned interested observers not to trespass onto the site to get a better view, and noted that local police will patrol the surrounding woods.