When the United States was going through the highway boom in the 50s and 60s, there were a lot of planned routes through every major city. Most came to fruition, but many were not constructed due to community opposition or lack of funding. Interstate 78 in NYC is one of those unbuilt routes. It currently ends in New Jersey at the Holland Tunnel entrance, but there were plans for it to go through the tunnel, through Manhattan via the Lower Manhattan Expressway (unbuilt), over the Williamsburg Bridge to Brooklyn, via the Bushwich Expressway (Unbuilt) to Kennedy Airport, then north to the Bronx. The map above shows part of the route.
I actually think about, how NYC would be different if all the routes that were planned were actually built. It would have been a very different place. These additional routes would have eased congestion on the road network, but destroy many communities. Furthermore, if you build new roads it creates an induced demand where more people than before would drive. So these new roads would have eventually become congested anyway.
Canal Street is the arterial street in Manhattan that drivers take to drive between the Holland Tunnel and the Williamsburg & Manhattan Bridges. These drivers exited highways in New Jersey and Brooklyn and have no choice, but drive on local streets.
But is it better to have congestion on the highways and not on local streets? I think so. This is how it is now in NYC. I-78 would have traveled in lower Manhattan connecting the Williamsburg Bridge to the Holland Tunnel. That is a major corridor for drivers to travel between Long Island and New Jersey, but there is no highway link between them. Currently, vehicles crowd the street, sometimes taking over an hour to travel one mile. I cannot imagine that being good for air quality.
The original plans for the I-78 Lower Manhattan Expressway called for an elevated highway for the majority of its route which would require a lot of condemning of homes. That is one of the major reasons to why it was not constructed. It would have been an eyesore like some of NYC’s current elevated highways.
So today NYC is plagued with crippling congestion in its downtown area. I think the only feasible solution that people would support is a underground expressway connecting the bridge and the tunnel. I can see that happening one day because we are delaying a problem that continues to get worse. It would be extraordinarily difficult, but I find it cool to just picture such an achievement and driving through it.
The unbuilt Lower Manhattan Expressway
(http://www.nycroads.com/roads/bushwick/)
Well a buried expressway would be similar to Boston’s Big Dig. (http://en.wikipedia.org/wiki/Big_dig) so it is feasible. The problem would be that New York’s underground is much more crowded than any other city in the states. You have buried pipes, wires, trains, viaducts and some things that are so old they aren’t even on any plans. I would assume the costs and logistics would be huge (think about something significantly wider than the subway you just talked about (http://sites.lafayette.edu/bahrinmotion/2012/09/17/second-avenue-subway-in-nyc/)). Of course it may still be the best option, but on current trends something like that won’t happen for decades, if we’re lucky.
Another example of an unbuilt interstate in Manhattan is Interstate 495. It is actually more of a gap. While the eastern terminus of I-495 is in Riverhead, Long Island, NY, the western terminus is in New Jersey where it hooks up to New Jersey Turnpike and the highway itself appears to end up continuing further west as Route 3. So in reality, the western terminus is actually the Holland Tunnel, and then to get to the New Jersey section of I-495, motorists would have to deal with stoplights on 34th Street and then I-495 appears again as Lincoln Tunnel and then into New Jersey. There were plans for an expressway back in the 1970’s to kill the gap but it was cancelled. I-495 on Lincoln Tunnel and New Jersey is no longer considered “Interstate 495”, it is now a New Jersey state highway 495.
Part of the planned I-78 that would have went north to the Bronx would connect to today’s I-295 (Clearview Expressway) across the Throgs Neck Bridge.