Long Island Additional Evacuation Capacity/Amtrak Trans Sound Rail/I-180/I-80 Southern Westchester Link

 The northern U.S. region MUST have an additional bypass, from I-80 & the existing northern terminus of the New Jersey Turnpike through southern Westchester County to I-95, together with a bridge-causeway linking New Rochelle to Long Island, together with a new cross sound rail link, as it is impractical to add a raillink to the Throggs Neck.

 

This bypass starts immediately east of the existing eastern terminus of I-80, along the Northern Railroad corridor, briefly elevated to avoid the marshlands potential flooding and to cross over Route 4, before descending into a cut and cover tunnel. 

 

Further north, this cut and cover tunnel veers northeasterly. easterly, towards a golf course, to emerge from its portal at the Palisades Parkway, to transition to a new span across the Hudson River, to Yonkers, landing at the short block or so long "Bridge Street" continuing east along Ludlow Street, heading towards the Saw Mill River valley and Parkway.

Technical advice is here solicited for the best way to cross the high mountain ridge.  As I doubt that anyone wants a Maryland I-68 style deep mountain cut, we need to explore tunneling techniques, likely with a pair of large tunnel bores, sufficiently wide to render at least a full set of right-hand shoulders.

 

Said tunnels would emerge just west of the Saw Mill Parkway, with an artistically styled span crossing over, continuing east into a cut and cover tunnel segment displacing and replacing the Lincoln High School, and so continuing to a second artfully designed viaduct to pass over I-87 and along through the southern parking area of the Casino-Raceway Park, and subsequently over the Bronx River Parkway, to enter a cut and cover tunnel segment in Mt. Vernon along 2nd Street, to a set of connections with the I-684 North Central Road Upstate Gateway Expressway Tunnel system, with I-80 continuing east over the Hurchinson River Parkway upon a new artfully styled arched span, and enter another cut and cover tunnel segment, along the Metro North to New Rochelle (with no access to downtown Pelham).

 

I-80 Tunnel would emerge along the western side of the I-95 corridor, with generous use of tunnel box enclosure for muffling traffic noise and giving back surface space.

 

Immediately north, northeast, the I-180 spur (cut and cover) would veer towards Long Island Sound via a thankfully located bit of industrial waterfront, along with an all new railroad spur.

 

Both the expressway and the railway would here enter into a new box tunnel causeway, with the roadbed just below the waterline, but with the tunnel box standing up as a new pier- shaped land-way, and continuing into the Long Island Sound, with a drawspan, or turn-style span for the railroad, and an overhead span for the expressway.

 

This causeway would land in Long Island at the northeastern corner of the Port Washington peninsula, and continue as enclosed tunnel box, either directly off the existing northeast shoreline, if not a new swath paralleling just inland, so swinging to avoid displacing the dwellings along the coast, before entering a golf course.

This project would continue south to the corridor of the previously planned Roslyn Freeport Expressway which was in-explicitly cancelled in 1953. 

I-180 would employ generous use of tunnel box enclosure and have its interchange with the Long Island Expressway, with a spur continuing south at least to Mineola.

 

The railroad component is particulalry needed as the grade of the Throggs Neck is impractical for a railway, and because this New Rochelle to Port Washington causeway is far more financially and engineering practical that a railroad tunnel crossing under the Sound.

Yonkers, N.Y. Hudson River Bridge/Northern Metro Regional Bypass

 

The George Washington Bridge NEEDS alternative routes- the NYC Metro Area must have additional trans Hudson River crossings.  Northwards to the Tappan Zee Bridge, Yonkers is the best, for connecting with the existing east-west Cross County Parkway- a freeway reconstructed during the 1960s, 1970s and early 1980s that excludes trucks.

Yonkers, NY authorities appear to suggest the preferred site, marked by the naming of "Bridge Street" at the east west axis of Ludlow Streets, where it would land, with its approach eastwards into a hill by Route 9, where the highway would continue within tunnel, with connections to and from the north to the Cross County Parkway.

 

Extend that Yonkers, Ludlow Street axis to New Jersey, where it would land.  It would have connections with the Palisades Parkway.  And it must have a minimum of 6 lane mainline continuing west, as simply linking to the Palisades Parkway is problematic given the lack of a continuous traffic light free link to I-95.  Years ago, 1940s-1950s, the Yonkers, N.Y. - Alpine, New Jersey bridge was proposed to have an all new freeway continuing west, which was not built.  Instead, have a tunnel that arcs southward to follow the Northern RR, to connect with I-95/I-80.  

The I-80/I-95 to bridge link would be via tunnel, cut and cover along the Northern Line., and then curved towards facing Yonkers, with portal by the Palisades Parkway.  Curved portion would be bored to avoid surface disruption, emerging just past Montammy Golf Club, at the Palisades Parkway, to the bridge to Yonkers, N.Y., along Ludlow Street.  A minimum 6 travel lane facility could be either a single tunnel with two levels, or a pair of single or two level tunnels.  Existing 57 foot diameter TBMs require a pair of tunnels, each with a single 3 lane roadway, with only about 6 feet of shoulder space, or a double level 2 lane roadway with the 6 foot shoulder space.  Larger tunnels, 62, 67, 72 feet diameter would be preferable, particularly for line of sight within tunnels that are curved.

 

In Yonkers, this moled land approach tunnel might be a short segment, that emerges to cross atop the Saw Mill River Parkway, elevated over the valley, before entering a second tunnel further east as the topography rises, that extends further east to cross I-87, the Raceway Park parking lot, and the Bronx River into the City of Mt. Vernon, transitioning to cut and cover tunnel along 2nd Street.

 

Or instead it could be continuous with the west Yonkers segment descending to pass beneath Saw Mill River.

 

In Mt. Vernon, this cut and cover tunnel follows 2nd Street before turning south along the old N.Y., Westchester & Boston RR corridor, and continuing in the Bronx alongside that same RR's currently extant Dyre Avenue IRT line, to connect to and from the south with I-95 via an augmented 222nd Street exit, extending to the Throggs Neck Bridge Expressway, and providing a valuable new traffic corridor for handling potential emergency situation evacuation traffic.