Friday, May 6, 2016

Proposal: A Sheridan Expressway Deck - Westchester Avenue to 174th Street Vicinity:

Sheridan Expressway Deck - Westchester Avenue to 174th Street:

To construct a new boulevard on a deck atop the existing surface segment of the Sheridan Expressway, in the area between Westchester Avenue and 174th Street, taking advantage of the topography of the hill to the west, as an alternative to the plan to convert that existing freeway segment to a boulevard that would still be fed directly by freeways at both ends.

Existing planning fails to look to the long term of greater population densities and development in the South Bronx, and other factors that all point to increased use of the Sheridan Expressway over the future decades.

It fails to adequately consider massive new development in the Port Morris area, including that envisioned by the Re-Think NYC proposal to extend LaGuardia Airport into Port Morris, Hunts Point.  It likewise completely fails to consider the significant amount of new development achievable with a future project to demolish the Sheridan Expressway's southern elevated segment, and that which it connects directly, the hideously ugly elevated Bruckner Expressway, placing it with a line of new buildings flanked and atop a new underground replacement, with the parallel RR likewise decked over.

It likewise fails to adequately consider massive new development with the development envisioned for the Mott Haven area, along the parallel route to the Sheridan of the Deegan Expressway.  In particular, it ignores the ramifications of the recent decision to not widen the Deegan corridor for merge lanes instead providing such by re-striping the out lanes as merge lanes, thus reducing the number of through lanes from 3 to 2.  So narrowing the Deegan, while refusing to consider any long term design modifications for it, is only likelier to shift some of the truck traffic to the Sheridan.

It wastes the sunk costs of the existing Sheridan Expressway roadbed that was recently torn out and completely replaced with a high quality concrete roadbed to accommodate decades of future heavy truck traffic, as it would again rip out the roadbed in order to build a new boulevard upon a narrowed right of way, so narrowed to increase the real estate development square footage to the east.  Apparently, no costs comparisons were considered of the lost value of the to be demolished roadbed, versus the added cost of a deck over of the adjacent railroad along the west side of the Bronx River northward from Westchester Avenue to provide the extra development space.

It furthermore likewise squanders the additional opportunity to increase the square footage for new development by having the new buildings partially cantilevered over the space of the service roads.

It does all of this with the idea of accommodating new neighborhoods envisioned alongside in new large apartment-condominium buildings along a Sheridan boulevard that would remain directly fed by expressways at both ends, and thus have far higher levels of vehicular traffic, and such conflicts with pedestrians, than a boulevard upon a deck atop the existing Sheridan retained as a continuous expressway.  Retaining the existing expressway beneath this deck between Westchester Avenue and 174th Street would keep the bulk of vehicular traffic off of the new boulevard thus rendering it a far far more neighborhood-pedestrian friendly street- a point completely overlooked in all of the mania about 'freeway removal'.

It wastes the opportunity to reduce the costs of doing so, by planning this new development together with retaining the expressway beneath the deck, potentially reducing its costs by designing such buildings to serve as the outer walls and supports of the expressway deck, with the buildings so designed to have their '1st' floors facing the top of the deck, with the existing ground level as service entry points, such as for truck delivery.  Doing this now would certainly be far easier and less expensive than in the future either disrupting traffic to dig a cut and cover tunnel, or constructed a deck and having to modify the buildings to raise their street level entryways one floor up (while not retaining the utility of having the service road as an underground delivery points).

It perpetuates a wasteful trend of reducing express transportation corridors for the sake of development, as with the nearby truncation of the Dyre Avenue IRT line (former N.Y. Westchester & Boston RR) at Lebanon Street, severing it altogether from its southern continuation to Westchester Avenue and Hunts Point.

Demolishing the existing surface segment of the Sheridan to construct a narrower boulevard that remains directly fed by freeways at both ends is neither necessary or desirable for the laudable goals of creating new neighborhoods along the Bronx River that would be far far better served by retaining this expressway segment beneath a new deck featuring a new boulevard that would serves as a far more neighborhood-friendly surface street, while providing a significantly superior express highway network for the region that acknowledges the significant new infill urban development for the City.

Sunday, May 1, 2016

1955 Mid Town Manhattan Expressway Elevated & Tunnel Options

from the "Joint Study of Arterial Facilities - New York - New Jersey Metropolitan Area" - January 1955, by The Port of New York Authority and the Triborough Bridge and Tunnel Authority TBTA: Robert Moses Chairman; George V. McLaughlin; William J. Tracy; George E. Spargo - General Manager and Secretary:

PNYA: Commissioners: New York: Howards S. Cullman, Chairman; F. Moran; Bayard F. Pope; S. Sloan Colt; Charles S. Hamilton, Jr.; Chas H. Sells; New Jeresy: Donald V. Lowe, Vice Chairman; Horace K. Corbin; John F. Sly; Jess Harrison Davis; David Van Alstyne, Jr.; Dow H. Drukker, Jr.

This 1955 book featured two options for constructing an east-west Mid Town Manhattan Expressway- Elevated and Tunnel.

Owing to its preference for elevated roadways over those in tunnels, this 1955 report addresses the elevated option first.


The 1955 study's option of an elevated version of the Mid-Town Manhattan Expressway, in a nutshell

3 lanes per direction upon a 100 foot (1/2 block wide) new swath right of way across Manhattan along 30th Street's southern side, except for the 2 and 1/2 blocks between just west of 10th Avenue and nearly midway between 8th and 7th Avenue where it so ran along 30th Streets northern side.

Interchanges situated at the west and east, plus three between:

- at the west with the Lincoln Tunnel and West Side Highway, plus a westbound off ramp and eastbound on ramp at 12th Avenue.

- at the east with the Queens Mid Town Tunnel and the East River Drive, plus a westbound on ramp and eastbound off ramp at 2nd avenue, with the latter ramp also to 1st Avenue.

- 2 additional interchanges respectively between 5th Avenue and Broadway, and 6th and 7th Avenues- each with left hand access ramps within the media space for better space utilization, with the option of being designed to support a line of new buildings, with elevator access via the median area.

Elevated Version of Mid Town Manhattan Expressway 
with Left hand ramps in Median

Would include the option of support provisions for ultimately constructing a line of new buildings atop the elevated expressway.  These buildings would be served by elevators located within the median space, connecting below to the street level and perhaps beneath to the underground level set aside for automobile parking.

As a product of Robert Moses, who favored elevated structures over tunnels, the 1955 study predictably favored such for its suggestion for the Mid-Town Manhattan Expressway

An elevated expressway, from its connection with the West Side Highway, would start as a depressed highway in the center of a widened 30th Street to 10th Avenue. At this point, it would swing to the north side of 30th Street to make connections between 10th and 9th Avenues with the Lincoln Tunnel Third Tube approaches now under construction. After underpassing 9th Avenue, the six-lane expressway would rise to overpass 8th Avenue and continue across Manhattan as an elevated structure. Between 8th and 7th Avenues the roadway would recross 30th Street and occupy a one-hundred-foot right-of-way immediately south of 30th Street. After overpassing 2nd Avenue, the expressway would swing north to follow the 30th Street alignment as a four-lane elevated expressway to connections with the East River (FDR) Drive.

At 1st and 2nd Avenues, ramps would be constructed to provide access to and from the Queens-Midtown Tunnel via 1st and 2nd Avenues and the existing tunnel approach roadways. Access to the expressway would be provided in each direction in the section between 5th and 7th Avenues. 

If the expressway were constructed, it is estimated that it would be used to its estimated capacity of 24,000,000 vehicles a year. 

Air-Rights Development

The Joint Study indicated the feasibility of designing the elevated expressway to permit the construction of new buildings over the elevated portion of the expressway two three-lane roadways could be separated and elevators to serve the overhead development could occupy the space.  The access ramps to and from the midtown avenues could also be provided between the roadways.

In addition to the air-rights development, commercial space could be provided at street level and parking areas for 1,300 vehicles could be provided in basement areas under the expressway.  The revenues to be derived from such developments could be expected to protect the City from tax loses due to construction of the expressway.  It is doubtful that they would also contribute to the expressway cost.

Estimated Cost

It is estimated that the cost of the elevated expressway alone would be $77,000,000, of which $33,500,000 represents real estate.  If the expressway were designed to permit the overhead development, the cost would be increased by $14,000. 


Revenues from possible development over or within the toll-free expressway property would be of a minimum nature.  It would therefore be necessary to finance the expressway out of Federal, State and local funds.

Would include a basement level - unspecified if it were to be continuous along the entire length of the elevated segment - for automobile parking, with no apparent consideration of using such for additional through lanes, or simply for a cut and cover tunnel without the elevated roadways- suggesting a bias against tunnels.   Though this proposal was confined to its 100 foot wide new swath along 30th Street, adding that to that street's 60 foot wide building line to building line conceivably meant to a total possible right of way width of 160 feet.  Thus, a significantly wider expressway would have been feasible as a cut and cover tunnel within this 160 foot right of way.



Elevated for most of its length, its wester-most segment was to be below ground level in an open trench, with the expressway under-passing 11th, 10th and 9th Avenues, before rising up in the area to the south of the Beaux Arts James Farley Post Office Buildings, to cross over 8th Avenue, thus giving eastbound travellers a view of Pennsylvania Station (and the later constructed Madison Square Garden), and over-passing each of the successive north-south Avenues.

Its 100 foot width represented one half of the space between 30th and 29th Streets.  This would accommodate 3 travel lanes, each 12 feet in width in each direction, adding up to 72 feet, with no shoulders, plus a center median where the access ramps would be located, thus accessing the expressway to and from its leftmost lane in each directions- a design chosen as more space compact, as well as useful for locating elevators for new buildings to be erected above.  Its 100 foot width and center median located access ramps all represented efforts to reduce the right of way requirements (width), and the idea of erecting new buildings atop represented an effort to reduce the facility's long term property tax burden via replacing the buildings removed for clearing its path.


The 1955 study's option of a tunneled version of the Mid-Town Manhattan Expressway, in a nutshell:

2 cut and cover tunnels, each with 2 lanes- westbound tunnel beneath eastbound running 30th Street; eastbound tunnel beneath westbound running 29th Street.

Interchanges situated at the west and east, with the added option of one more centrally located:

- at the west with the Lincoln Tunnel and West Side Highway, plus a westbound off ramp to 9th Avenue.

- at the east with the Queens Mid town Tunnel and the East River Drive, plus a westbound on ramp and eastbound off ramp at 2nd Avenue.

- more centrally with a set of ramps between 5th and Madison Avenues

The Tunnel option possessed the supreme advantage of requiring at most a fraction of the building displacement of the elevated option, as the tunnels would be located beneath the existing right of way of 29th and 30th Streets, with displacement, and thus displacement-replacement confined to the various access points.

Yet the 1955 report did not favor it, due to the greater stated projected construction costs and for providing only 2 rather than 3 lanes in each direction.

The Joint Study disclosed that while physically feasible, a vehicular tunnel across Manhattan Island in the same midtown area would be prohibitive in cost.

It would be necessary to build two separate tubes under adjacent crosstown streets. A two-lane eastbound tube could pass under 29th Street; a two-lane tube westbound under 30th Street. Ventilation buildings would be located in the block between 29th and 30th Streets fronting on the west side of 8th Avenue and the east side of Lexington Avenue. The least costly type of construction for such a tunnel would be the steel-bent and concrete subway-type, installed by cut-and-cover method.

The tunnel providing only two lanes in each direction would, of course, have only two-thirds the capacity of a six-lane expressway. Provision of more than two lanes in each tube is not feasible due to limitations imposed by building foundations on either side of 29th and 30th Streets and extremely high costs. Limited street access in Midtown could be provided in the vicinity of 5th Avenue at a cost that would depend on the degree to which the interchange was developed.

The tunnel providing only two lanes in each direction would of course have only two-thirds the capacity of a six-lane expressway.  Provision of more than two lanes in each tube is not feasible due to limitations imposed by building foundations on either side of 29th and 30th Streets and extremely high additional costs.

Estimated Cost

The estimated cost of a crosstown tunnel with no surface connections at Fifth Avenue would be approximately $119,000,000 including real estate.  The estimated cost with a single-lane entrance and a two lane exit, to and from the west only, at Fifth Avenue, would be approximately $134,000,000.  The estimated cost with single-lane entrances and two-lane exist in each direction at Fifth Avenue would be approximately $145,000,000.

The 1955 report is not entirely clear with its cite of "Provision of more than two lanes in each tube is not feasible due to limitations imposed by building foundations on either side of 29th and 30th Streets and extremely high costs".

A tube with 2 foot wide outer walls, with 2 lanes at 12 feet apiece and no shoulders would be 28 feet wide.

Adding a 3rd through lane would bring the width to 40 feet.

Yet the east-west streets are 30 feet wide from curb to curb, and a total of 60 feet wide from building line to building line.

30 feet is just enough for 2 continuous travel lanes, without continuous shoulders, though it would still be feasible to construct emergency pull over areas within the tunnels as they passed beneath the north-south avenues.

60 feet is enough for tunnels with 3 continuous travel lanes, plus a shoulder.

Alas, the report fails to distinguish between matters of building foundation stability, which could be compromised by an adjacent excavation removing the soil that helps frame the load-bearing foundations, a problem with smaller-older buildings; or if such foundations physically intruded into the space beneath the sidewalks, or rather, such foundations had adjoining vaults -- that extend beneath the sidewalks.

The buildings along 29th and 30th Streets appear to be a mix of different building types- a topic the 1955 report does not go into in any detail.

More information would be needed about the strengths of the foundations and the soil conditions, as well as any under-sidewalk vaults and the willingness to take a portion of such for the underground right of way, to better ascertain the feasibility of a somewhat wider tunnel.   As it is relatively doubtful that a building would actually have its load-bearing foundation beneath the sidewalk, the two likeliest issues would be soil stability for older buildings with weaker foundations, and those with underground vaults beneath sidewalk space.

As adding a third lane to a 28 foot wide tunnel structure would bring it to 40 feet in width, thus extending out 5 feet past the curb lines on each side, while leaving 10 feet on either side between its outer walls and the above ground building lines, the 1955 report arguably could have gone into some greater detail, especially considering the failure to discuss condemning a mere 5 foot underground easement along the outermost sidewalk space, and the feasibility of any necessary stabilization of nearby building foundations, while nonetheless favoring condemning a 100 foot wide swath of entire buildings for the elevated option!

As can be seen from the 1955 study map renderings, building displacement for the Mid-Town Manhattan Tunnel would have been a fraction of the favored elevated option, being confined to its proposed transition points and its access ramp locations.  Transition points are shown for the eastbound tube in the vicinity of 10th and 9th Avenues, its approach to the 5th Avenue interchange westward to 6th Avenue, and to the east of Lexington Avenue to a one and one half block new swath cut to 2nd Avenue.  Such are shown for the westbound tube for the same cut from 2nd Avenue to Lexington, along the south side of 30th Street from midway between Lexington and 4th Avenue to the 5th Avenue interchange between Madison and 5th Avenue, and along the northern side of 30th Street from just east of 8th Avenue to the connection with the Lincoln Tunnel Expressway about midway between 9th and 10th Avenues.   Additional building displacement would be indicated for the north-south running connections located east of 3rd and 2nd Avenues to the the Queens-Mid-Town Tunnel.

 By ending its discussion about the reduced capacity of 2 rather than 3 lanes per direction with the phrase "extremely high additional costs" the 1955 report sidesteps any consideration of providing additional tunnel capacity by other means, not only with an inadequate discussion of the construction feasibilities, but also that of the potential staging.  It gave no apparent consideration for tunnels with more than a single level -- e.g. duel level tunnels each with 2 lanes atop 2 lanes providing a total of 8 lanes -- either constructed at once or staged with the eventual construction of an additional underground level.  Nor did it consider a design permitting a concurrent or staged set of additional parallel tunnels beneath the adjacent east-west streets- an omission matched by its lack of a full consideration of the costs of the displacement and replacement of the real estate costs of the elevated option.

An Anti Tunnel Bias:

Owing to the elevated option's significantly greater amount of displacement - aka demolition - of existing buildings, versus the tunnel option, the 1955 report certainly understated - to put it mildly - the local opposition entailed by such, not only upon grounds of disrupting existing building activities but as well architectural and historic preservationist concerns.  As doubtlessly each block in an area as densely constructed as Manhattan is going to include structures of significantly architecturally if not historic interest to engender significantly increased local opposition, as occurred with the western segment of the parallel proposed Lower Manhattan Expressway though So Ho displacing numerous architecturally interesting Cast Iron buildings, the report does not really address the matter of building loss really that adequately, as such concerns are not necessarily easy to quantify.  Rather it limits such consideration to the simple matter of property tax revenue, and hence does this with its proposal of constructing a line of all new buildings atop the elevated expressway, which would essentially run through these new building's 2nd floor.  Notably, it does not give a full cost comparison between the two options that would fully adjust for the relative construction costs including those of clearing a new 100 foot wide swath across Manhattan and constructing replacement buildings, versus the tunnel option's greater preservation of existing buildings.

For the option of clearing a new 100 foot wide swath for the primarily elevated option, the 1955 report gives a figure of $35.5 million for real estate property acquisition out of a total cost of $77 million - thus translating to construction costs of $43.5 million for the primarily elevated option, while noting an additional $14 for design provisions to permit the eventual construction of the new buildings atop - thus translating to $91 million total, for a 6 lane facility, not counting the costs of the replacement buildings.

For the option of a set of cut and cover tunnels beneath 29th and 30th Streets, with relatively a fraction of the amount of real estate clearing for the access points, the report fails to give a full breakout of construction and real estate acquisition costs.  For that it simply gave figures for a total cost of either $119 million, $134 million or $145 million, variable upon the access ramps in the vicinity of 5th Avenue, with the cheapest having no access ramps there, and the next having such ramps only to and from the west.

By neither breaking out the separate costs of the right of way and construction costs of the tunnel option, nor providing any cost estimates for the real estate replacement costs of the elevated for requiring the clearing of a new 100 foot wide swath, the report was biased against the tunnel.

Would such new buildings cost less, or more, to construct than the $35 million given as the cost of acquiring the existing buildings for the elevated option's 100 foot wide continuous new right of way, let alone the costs of adequately compensating the displaced numerous resident and businesses in so many buildings with adequate replacement building space before removing their existing buildings?  Such would be significantly costlier for a project clearing a new 100 foot wide swath across Mid Manhattan than the fraction of such displacement for a tunnel with its mainline beneath existing right of way with displacement limited to access points as ramps and transitions.  The report alas makes no discussion of this, failing even to coordinate such say with any of Robert Moses' plans for large scale real estate removal and redevelopment elsewhere within NYC.

By neither listing the replacement costs for the building, nor separating the construction and real estate acquisition figures for the tunnel, the report prevents a cost comparison that may show the displacement-replacement costs approaching if not exceeding the costs of excavation and construction of tunnels beneath 29hth and 30th Streets with a fraction of the displacement-replacement costs for the access and transition points.

With regard to the short term costs of right of way acquisition and construction, and long term costs such as property tax revenues, the report's failure to separate construction and real estate costs for the tunnel option, while likewise failing to list the costs of the replacement buildings of the elevated -- touted for restoring the long term costs of the loss of property tax revenue from the buildings displaced, represented a bias against the tunnel.


Reviving the elevated option, or any other such option requiring removing a swath of buildings across Manhattan, would be a political nightmare.  Conceivably, the elevated option with buildings atop would have been architecturally interesting.  However, its removal of a continuous swath of buildings across Manhattan, thus inevitably including numerous architecturally significant buildings, would render it quite likely to succumb to preservationist opposition, especially with the available alternative of the under-street tunnel option.

Reviving the under-street tunneled option would make immense sense.  It gets the job done with a fraction of the building displacement, within an enclosure to contain vehicular traffic noise and emissions- accommodating and reconciling greater and more diverse human activity within an existing footprint.

More recently developed construction techniques would only make it more feasible.

Slurry wall construction where the outer walls are constructed before the excavation between would make the project far more feasible, particularly with regard to areas alongside older/smaller buildings that lack the substantial foundations of newer/larger to withstand the nearby excavation's soil removal.

Furthermore, such slurry wall construction would better facilitate a subsequent top down construction, where a pre fabricated roadbed could be installed atop, before the main amount of excavation and construction of the full tunnel box and roadbed.

Hence it may be more practical for the tunnels to be somewhat wider, depending upon any sub-sidewalk vaults, and the willingness to partially remove such.

A tunnel tube with 2 foot wide outer walls, a pair of 12 foot wide lanes, plus an 8 foot right-hand shoulder would be 36 feet wide; and one with a 3rd travel lane would be 48 feet wide, beneath a 29th and 30th Street with a curb to curb with of 30 feet, and a building line to building line width of 60 feet. 

Lowering the tunnel an additional level could allow the main roadways to pass beneath any space for sub sidewalk vaults.  This could complicate the slurry wall construction by requiring removal and replacement of the underground vaults.  But it would provide the opportunity to locate access ramps within the existing street right of way to descend into a top collector-distributor tunnel level before swinging right and down to merge with the underground freeway, thus reducing the need for displacing buildings for access ramps.  Locating the access ramps within the center of a street - center loader ramps -- would not only avoid building displacement but be far more compatible with pedestrian and cyclist activity by avoiding the conflict of standard side loader ramps located upon either side of a surface street.  As 29th and 30th Streets run in the opposite direction of the tunnels that would be beneath, such ramps would have to turn to align with the north-south streets, unless of course the running directions of 29th and 30th Streets were swapped.  Avoiding building displacement in Mid Town Manhattan would to some degree off set the added expense of a deeper excavation.

With the slurry walls extending sufficiently deeper, a second through level below would allow twice the capacity, though due to space constraints, access ramps would be precluded, except towards its western and eastern ends, thus having this lower through level better cater to longer distance travel.

Top down construction would allow the top collector-distributor and the middle -- upper -- through level to be completed initially, permitting deferring construction of the lower level.

A set of twin tunnels beneath 29th and 30th Streets, each with 2 or 3 travel lanes and a right hand shoulder would provide 4 or 6 continuous through lanes, and with the lower level, provide 8 or 12 continuous through lanes.   The 60 foot building line width could conceivably allow just enough space for even the 3 lane version to have an additional lane for on and off ramp access merge.

The straight street grid of Mid Town Manhattan would make this under street vehicular tunnel project more environmentally practical then areas of NYC lacking such a grid.

New cashless tolling technologies would make funding this project far more feasible, and could vary the toll not only upon the time of day, but upon the distance via the installation of such toll readers upon the access ramps.