Over the years, several other highways were proposed, only to be cast aside as too expensive, too challenging, or too disruptive to neighborhoods.
Some proposals were pursued for decades, but died in the face of opposition by civic groups.
"Any project you do is going to have some issue that impacts somebody negatively," said Barry Seymour, executive director of the Delaware Valley Regional Planning Commission. "Whether it's a 'not in my backyard attitude' that we don't want any type of construction or whether there's concern about meaning more traffic or whether it's a risk of impacting an environmentally-sensitive area or an historic site, these are complicated projects."
"In some ways it's a miracle anything happens, they're so complicated," he said.
The Manayunk Expressway was considered to mirror the Schuylkill Expressway on the east side of the river. That would have doubled capacity by allowing four lanes for each direction of travel.
The Crosstown Expressway would have cut through Philadelphia at South Street, connecting I-76 to I-95, just like the Vine Street Expressway. The interstate would have served as the southern border of Center City. But it ran into serious opposition from neighborhood groups worried about the need to relocate hundreds or even thousands of residents already living there. Various mayoral administrations tweaked the plan, even considering changing from a sunken highway to a capped highway, and adjusting the location off of South Street itself, but the plan never broke ground.
The Ten Mile Loop was the nickname for a highway that would have directly connected the Schuylkill Expressway in Montgomery County to I-95 at the northernmost end of Philadelphia. It would have stemmed off the Conshohocken Curve.
The Double Decker.
Due to the geography of the busiest stretch of I-76 -- penned in by the river on one side and a rock cliff on the other -- the most ambitious plan proposed building a second highway on top of the current one. While one might imagine numerous reasons this could be challenging to accomplish, the problem inevitably is money.
"You've got a rail line and the rock ridge on one side, so you can't move the rail line," said Seymour. "You've got the river on the other side, you can't move the river. So, you could do some really expensive projects like double decking, and people have proposed that and looked at it in some ways; that means raising dozens of bridges so that becomes enormously expensive."
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