CORRECTION: During the weekend traffic will be detoured around the bridge project site for that portion of roadway that will be affected. For example, when working on the eastbound span of the bridge, eastbound traffic will be detoured around the work site, not on westbound lanes. This information was incorrect in an earlier version of the story.

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Four weekends, totaling nine-and-a-half days, or two-hundred and twenty-eight hours.

That's the window for the Pennsylvania Department of Transportation and contractor JD Eckman to demolish the Route 581 highway bridge over 10th Street in Lemoyne and build a replacement, all while traffic continues to move unabated through the I-83 York Split and Route 581.

It is an impossibly tight schedule. And were it not for almost a year's worth of prep work, it would be impossible to carry off. A traditional demo-build, by comparison, would take a year-and-a-half of phased construction, lane closures and nightmarish traffic backlogs.

The bridge rebuild is the capstone to the $23 million rebuild of the Interstate 83 York Split, a project that started in 2012 and should be done by the end of this year.

To pull it off, PennDOT and Eckman have pre-built the bridge, the two spans (east- and west-bound) taking shape over the last year in the construction yard off of Lowther Street. In the construction yard the spans are complete: They had to be built and bolted together to make sure they would fit in the space of the current bridge.

Starting next weekend, the spans will be unbolted and split longitudinally into three or four sections - each weighing between 120 and 130 tons - and trucked from the construction yard onto Lowther, then onto 10th Street. From there they will be lifted into place by a giant 650-ton crane - which in and of itself is a construction project, being built on site akin to a giant Erector set. The pieces of the crane, a special order from Austria, began arriving Thursday afternoon, having cleared customs in Baltimore earlier in the day.

During each weekend, starting at 9 p.m. Friday, traffic from the span being constructed will be detoured around the construction area. However, traffic in the other direction will continue to flow normally over the bridge.

The yellow crane is unloading pieces of a bigger crane Thursday. PennDOT announces dramatic project time savings for the new Rt. 581 bridge that will span 10th Street in Lemoyne, replacing the 60-year-old bridge currently in place, May 28, 2015. Dan Gleiter | dgleiter@pennlive.com

Meanwhile, work crews will demolish the current span to make room for the new span. Once the old bridge span is gone, the new span will be lifted into place, then bolted back together and paved with concrete.

An entire span is expected to be demolished, moved, lifted, bolted, and paved each weekend, meaning that traffic should be flowing normally across the new span by 6 a.m. Monday morning.

It is an incredible orchestration of men, material, and traffic - one of the largest builds of its type in the region, if not the state.

Each day some 86,000 vehicles cross over 10th Street on Route 581. To close the bridge entirely would be to suffer backups and congestion on the scale of the I-81 tanker fire two years ago.

But the 60-year-old bridge over 10th Street "has reached the point to where it must be replaced," said Leslie Richards, PennDOT secretary. Richards called the plan "an innovative way to move construction ahead and be the least impactful on the traffic around us."

An interactive look at the project



Over the next several weekends PennDOT will perform major construction at the York Split on I-83. The project primarily entails replacing the Route 581 bridge over 10th Street in Lower Allen Township.

To help visualize the project, we put together the following interactive that shows how PennDOT will perform the work. This depicts the reconstruction of the eastbound span of the Route 581 bridge over 10th Street, which is expected to be completed in one weekend.

Note

Beltway improvements

If the bridge is the capstone of the York Split rebuild, it is only a step in the longterm plan to rebuild much of the Harrisburg beltway. Last year PennDOT completed the $6 million resurfacing of I-283 in Dauphin County, and this year it awarded a $5.5 million bridge preservation contract for the I-83 bridges between the Eisenhower Interchange and the south bridge.

Next year will start the reconstruction of the overhead bridges on I-83 at Union Deposit, Route 22 and Elmerton Avenue, with an eventual $112 million East Shore I-83 widening project scheduled for 2018.

PennDOT District Executive Mike Keiser said the work was "a long overdue investment needed here in central Pa."

Work on the 10th Street bridge is expected to start June 5.