The I-95/Cottman Avenue Interchange Improvement project is located in northeast Philadelphia.

"We did almost $75 million worth of other projects just leading up to this one," said John Eagan, project manager for Alfred Benesch. "Any time you are dealing with a project of that magnitude, the process becomes cumbersome."

Eagan said it took almost a decade to get to this final stage of the multi-phase project. Engineers on the team dealt with everything from handling red-bellied turtle habitats to designing seven massive bridge replacements on I-95.

Benesch provided highway/interchange design, structural design, and is currently supplying construction consultation services for the second phase of this project.

Improvements are geared to rehabilitate and widen the aging interstate; upgrade ramps; replace multiple deficient bridges; improve local streets; and provide traffic relief to the 170,000 daily users of I-95.

Benesch also designed the $34 million phase one interchange improvements, which included improvements to adjacent streets and intersections in the Tacony neighborhood of Philadelphia.

"There are a lot of agencies that had significant involvement," said Eagan. "Hopefully, construction will go as smoothly as design."

Construction is scheduled to begin in August and finish in late summer 2017.

The company has also did engineering work on large projects in the Lehigh Valley, including the Route 33 extension in Northampton County and the Route 222 bypass in Lehigh County, said Eagan.

The Pennsylvania Department of Transportation said the award is the largest construction contract in agency history.

PennDOT awarded the low-bid $212,325,000 contract to Walsh Construction Co. II, LLC of Canonsburg. The contract is financed with 90 percent federal and 10 percent state funds, said PennDOT.