Brooklyn Bridge Promenade Expansion Could Start in 2019

DOT's hypothetical concept for expanding pedestrian and bike access on the Brooklyn Bridge would build new paths over the steel girders that run above the main roadways. Image: DOT
DOT’s concept for expanding the walking and biking path on the Brooklyn Bridge would build new paths over the steel girders that run above the main roadways. Image: DOT

An expansion of the Brooklyn Bridge walking and biking path could get underway by 2019 if it’s folded into a rehab project that’s already in the pipeline, DOT Commissioner Polly Trottenberg said this afternoon.

The path is as narrow as 10 feet at pinch points and cannot comfortably accommodate the thousands of people who use it each day.

For now, the next step is a $370,000 feasibility study slated to wrap up in seven months. DOT has already conducted a preliminary assessment of conditions on the bridge path and posted a working concept for the expansion [PDF].

The idea is to widen the pathway by building on top of the steel girders that run over the bridge’s main roadways. Most of the wooden deck for walking and biking is four feet below the girders, so the expansions would be at a higher grade than the current path. Trottenberg said DOT will also explore expanding the concrete approaches to the wooden deck on both the Brooklyn and Manhattan sides.

If the concept proves unfeasible for whatever reason, Trottenberg said DOT’s attention could turn to the main roadway. “I think if the study finds out that it’s not feasible, there is going to be interest in seeing what we would do next in terms of potential traffic,” she said. “Look, the Brooklyn Bridge carries a lot of traffic… But I think certainly we’re seeing a lot of enthusiasm about the idea of making more of the bridge available for cyclists and pedestrians.”

In addition to the engineering challenges of expanding the bridge path, Trottenberg said DOT will also have to coordinate plans for the 133-year-old bridge with NYPD’s Counterterrorism Unit, the Landmarks Preservation Commission, and other agencies.

Widths vary significantly on the various portions of the shared pedestrian-bicycle path. Image: DOT
Image: DOT

While conflict between pedestrians and cyclists on the narrow pathway is constant, serious injuries are not common. Only three pedestrian injuries were reported on the bridge on 2015. “When we look at the data, at least the NYPD data, we have not seen that there have been a lot of injuries,” Trottenberg said. When Daily News reporter Dan Rivoli asked about prohibiting bike access to the bridge, Trottenberg said that is “not on our table at the moment.”

Asked about the timing of the project — which advocates and elected officials have wanted for years — Trottenberg and DOT Deputy Commissioner Ryan Russo told reporters that the agency did not previously have the funds to undertake an expansion of the path. “In terms of the moment, we’re not that far from the era when we struggled to keep the bridges up,” Russo said.

  • Jeff

    I wonder what the thinking is behind that 4′ of width reserved for pedestrians on what would otherwise be a physically-separated bike-only pathway?

  • J

    Spoiler: not a lot

  • J

    Great. It’ll only be abysmally terrible on the uphill and downhill sections of the bridge. Do you really need to spend $370,000 to find out that reconfiguring a space that is wildly too small is not going to solve the problem?

  • Seth Rosenblum

    Maybe they’re not sure they can do wheelchair access to the new pedestrian deck?

  • Jeff

    Good point! And 4 ft of clearance is the minimum for ADA I believe?

  • redbike

    > “The path is as narrow as 10 feet at pinch points”

    From pg 16 of the referenced nyc.gov/dot pdf, abeam the vomitory choking the Manhattan end of the ramp, there’s 7 feet width for pedestrians and 5 feet for folks on bicycles. A path is no wider than its narrowest chokepoint.

  • Albert

    “…certainly we’re seeing a lot of enthusiasm about the idea of making more of the bridge available for cyclists and pedestrians.”

    It wonderful that Commissioner Trottenberg is stating this publicly (the implication being taking back some space from motor vehicles). If she’d only run with it, she’d go a long way toward matching the daring of her predecessor.

  • ItsEasyBeingGreen

    It’s more of a pissoir than a vomitory 😉

  • BrandonWC

    The presentation says the study will “[e]xplore feasibility of closing & covering stairway” at that point, which would add at least 5′. I’m not sure what more to ask from a presentation announcing a feasibility study.

  • BrandonWC

    That’s a good thought, but the presentation states the new deck will be at the same level as and extend between the existing deck at both towers. So I don’t see leaving that 4′ for peds as an ADA issue (the new deck should actually be better for wheelchairs as the current deck dips between the towers and new one would be level).

  • HamTech87

    Maybe for bicyclists to pull over, rest, and take in the view themselves? Functions like a road shoulder?

  • HamTech87

    “In terms of the moment, we’re not that far from the era when we struggled to keep the bridges up,” Russo said.
    If the bridges are so fragile, shouldn’t the City be restricting heavy vehicle access?

  • sbauman

    As much as I would love to see the Promenade widened, I believe this approach is not feasible. The steel members on which are above and perpendicular to the roadway direction cannot carry weight. They are struts. Their purpose is to keep the inner and outer longitudinal trusses from bending towards one another due to weight on the floor beams. These struts are on what the projected projected Promenade expansion would rest.

    A similar situation arose when the Promenade was re-decked in 1982. It was proposed to close the Promenade, while it was re-decked. The only other East River crossing at that time was the Williamsburg. The bridge engineers told us that the struts could not take any vertical load.

    The cycling community came up with a plan to build a temporary deck that was supported solely by the inner and outer longitudinal trusses. Then Transportation Ameruso thought enough of the plan that it was included in the bid document and he required that 3 bids be submitted. One that did not provide access during construction; one that provided rush hour access and one that required 24/7 access.

    The winning bid did not use the cycling community plan. They built a deck directly above the Promenade that was supported by the inner longitudinal trusses.

    The winning bid for 24/7 access came in at $160K more than the low bid for no access. The cycling community estimated that the extra cost for 24/7 access would be $150K.

    If the Promenade is to be widened, it must also be raised. It must rest on the top of the inner longitudinal trusses. This way the expansion can be cantilevered over the roadway and still be supported solely by the inner trusses. This will result in a steeper grade on the Manhattan side. Somebody will have to check ADA regulations regarding the grade. There’s a longer approach on the Brooklyn side to avoid this problem.

  • Sean Kelliher

    The New York Times covered this story today too. You can read it here: http://www.nytimes.com/2016/08/09/nyregion/brooklyn-bridge-expansion.html

    However, what I found most striking was the comments section.

    Click the “Readers’ Picks” tab and see the top comments. They focus mostly on repurposing a vehicle lane for bicycles.

    Then click the “NYT Picks” and note what their editors selected. These focus mostly on banning bicycles.

    The difference is incredible.

  • ahwr

    If the bridges are so fragile, shouldn’t the City be limiting car and truck usage which cause the bridges to fail?

    More an issue with trucks than cars. And why do you think the bridge has a 3 ton weight limit?

  • rogue

    It’s a war out there, and they can’t win

  • ahwr

    Put in a jersey barrier to protect cyclists, how wide is the remaining two way bike lane? Probably 8 feet or less. Add in shy distance from both ends and the usable width could get down to 6 or 7 feet. So the call to repurpose a lane would quickly turn into calling for a lane on both sides of the bridge, not just one. The last entrance ramp on both sides is from a highway. Ramps the city just spent/is spending a lot of money to rebuild and widen. The cheapest lane to take for cyclists would be the inside lane then. Much less desirable for riders who want to enjoy the view. And then there’s the question of whether or not the bridge could support the jersey barriers.

    Sticking it to drivers sounds nice, but would it actually be cheaper and lead to a better product for cyclists and pedestrians? Or is sticking it to drivers the main point here?

  • Vooch

    Motor Traffic Is down 20% on BB.

    easy to reallocate One Lane

  • ahwr

    Much of the decline is due to off peak construction closures.

  • Vooch

    thanks !

    more empirical Proof that motor Lanes can be reallocated to more efficent uses. It’s Amazing how much Motor Traffic Is discresionary & induced

  • Larry Littlefield

    Look at the generational gap.

    Speaking as someone who seems to be in a minority of those my age and older, aka Generation Greed, and more in tune with those younger, the situation is obvious.

    Younger generations need to abandon the New York Times, and create their own. And they need their own banks, their own food providers, their own everything.

  • Larry Littlefield

    The solution is obvious. First start charging cyclists a nickel to cross the bridge one way. Put a box there. Make it the honor system, and allow them to put in a quarter for five crossings or a dollar for 20.

    Wait a year. And then reallocate space based on toll revenues.

  • ItsEasyBeingGreen

    I don’t think anyone is suggesting that being in the road bed is as good as being up top, but it could be done incredibly cheaply and quickly. I don’t know how old you are but I face the thought of my own mortality when I think of the speed of the cycling facility buildout in New York.

  • Albert

    “Or is sticking it to drivers the main point here?”

    I don’t think it’s quite so malevolent. The main point (to me) is simply to reclaim public space for people who aren’t in cars. When the city rejects excellent-if-not-perfect fixes like repurposing public space that already exists, in favor of expensive sci-fi jury-rigging of the tiny spaces currently left-over for non-drivers, the city is just continuing to enshrine the private car as the primary mode of transportation. And that way we’ll never get out from under.

    But it may not be too late to get out from under when we actually read that Polly T. is at least considering “making more of the bridge available for cyclists and pedestrians.” Of course, that’s only after a $370,000 study of the sci-fi idea “finds out that it’s not feasible.” But if she has to avoid being seen as “sticking it to drivers” in order to get the job done, well, maybe that’s $370K well-spent.

  • AMH

    I think they should instead improve access to that stairway so that it’s not so isolated. NYPD have turned what should be a nice park into a no-man’s-land.

  • JudenChino

    The stairs don’t take you to the park. They take you to Park Row and a placard parking lot.

  • ahwr

    it could be done incredibly cheaply and quickly.

    Can the bridge support two lanes worth of jersey barriers? And if after the rehab it can support extra weight, does repurposing a lane in each direction for cyclists kill any hope of a BRT lane over the bridge?

  • ItsEasyBeingGreen

    There are a bunch of plaza spaces under the ramps to the north. Brick paved, shaded, chess board tables, etc. They all have fences around them and have been abandoned along with the rest of the 1 Police Plaza exclusion zone.

  • Kevin Love

    A new born baby would have the same issue.

  • Larry Littlefield

    Those beams look thick to me. Are you sure they cannot carry weight, while also stiffening the bridge? After all, the floor beams serve as part of the stiffening box in addition to carrying the roadway.

    If not, could other beams be placed between them to do so?

  • Vooch

    the land consumed by the BB Highway Ramps etc should Be Sold to private developers which would raise close to $10 billion for the City, plus generate thousands of Jobs.

  • Jonathan R

    Those stairs were great. You could hike downstairs then ride Rose-Gold-Fulton-Water all the way to Battery Park much more quickly and easily than from Centre Street.

  • sbauman

    “Those beams look thick to me.”

    They are struts.

    “Are you sure they cannot carry weight, while also stiffening the bridge?”

    No serious weight. The struts can support the lights. The bridge will not collapse, if a sparrow perched on top of one.

    Any weight that is placed on the strut will deflect it downward. The downward deflection will move the inner and outer longitudinal trusses closer together at the top. You have two people hold a string. You push down on it. Your downward force pulls the two string holders closer together.

    “If not, could other beams be placed between them to do so?”

    There’s a weight problem. The Brooklyn Bridge’s live load is much smaller than any of the other East River bridges. It’s been nearly 35 years, since the Bridge was on my front burner. The number 1700 lbs per linear foot rings a bell. The other bridges are more like 10,000 lbs per linear foot. However, don’t quote me.

    The loading requirements for pedestrians are greater than for cars. The surface weight density of people crammed together exceeds that of most anything else. Remember the 50th anniversary of the Golden Gate Bridge? They closed the roadway and let pedestrians on it. The weight of those pedestrians flattened the arc of the bridge. Bridge officials were worried the bridge might collapse under their weight.

  • Jonathan R

    Yes, and if the BB is tolled, then highway-speed traffic can use the HLC (what we know as the Bklyn-Battery Tunnel) instead and bicycles can use the closed-off ramp to Park Row, the easternmost roadway lane, and a new ramp from Clumber Corner Park at the corner of Washington St & Prospect St in Brooklyn.

  • Jason

    As Vooch suggests, to me that just means that people have already found other ways of getting around so we may as well just make it permanent by converting a lane to a bike lane.

  • ahwr

    You want a bike lane sometimes off peak and often at night? That’s when brooklyn bridge traffic has seen most of its decline.

  • Vooch

    brilliant – Move NY

  • Alan

    Is it really a ‘sci-fi idea’ to build a couple platforms out of wood and steel, considering they managed to build the whole bridge out of like materials in the 1870s pretty much by hand?

    $370,000 sounds like salaries and overhead for a couple junior civil engineers for a year.

  • Alan

    It’s an engineering study as to whether the bridge can carry the load.

  • Andrew

    This is an excellent point: many drivers use the Brooklyn Bridge rather than the quicker and more direct Battery Tunnel. Apply toll parity and watch a significant chunk of Brooklyn Bridge traffic volumes instantly shift to the Battery Tunnel (and another significant chunk shift to other modes).

    Whatever modifications are made to the Brooklyn Bridge today should recognize that the current (badly broken) toll structure is not set in stone.

  • Vooch

    bike lane can carry more capacity than a motor lane on BB. If you want to move people than re-allocate one BB lane to cycling 24/7

  • Vooch

    dude like why are pedestrian bridges so easy and cheap to build ?

  • sbauman

    “dude like why are pedestrian bridges so easy and cheap to build ?”

    Like this one?

    http://gothamist.com/2016/01/22/squibb_bridge_lawsuit.php

    The cost and difficulty of building a bridge depends on the length of its span, its height and total capacity.

    Show me a pedestrian bridge that matches the Brooklyn Bridge’s main span of 1595 feet and 139 ft height above mean high tide. Then we’re comparing apples to apples.

    If it’s a suspension bridge, it’s going to have to be wider than 30 feet to reduce the effect of torsional vibrations that caused the Tacoma Narrows Bridge collapse. The extra width will increase the bridge’s cost.

  • Vooch

    30ft perhaps , but live load isn’t that high

  • sbauman

    “30ft perhaps , but live load isn’t that high”

    I gather you missed the portion of my reply to Mr. Littlefield that noted that pedestrian loads are greater than those for trucks and cars.

    The California spec for pedestrian loading is 90 lb/sq ft

    http://www.dot.ca.gov/des/techpubs/manuals/bridge-design-practice/page/bdp-3.pdf

    The live load on the 30 ft wide pedestrian path would have a live load of 90 x 30 = 2700 lb/linear foot. That already exceeds the live load for the Brooklyn Bridge.

    BTW, it’s one reason the Roeblings made the Promenade so narrow. The Promenade could have been built on top of the inner longitudinal trusses for the entire length of the span, instead of just at the towers. However, that would have permitted a wider Promenade. The wider Promenade would have permitted more pedestrians on the Bridge at any given time, which the Bridge could not support.

    By contrast, the Brooklyn Bridge can support 6 cars side by side. Suppose the cars weigh 4,000 lbs each and are 15 feet long. Their live load is 4000 x 6 / 15 or 1600 lbs/linear foot.

  • Vooch

    dude – been a PE for 35 years now

  • sbauman

    “been a PE for 35 years now”

    What load factor do you propose to use for pedestrians and what live load do your “easy and cheap” pedestrian bridges support? How wide a pedestrian path do these parameters imply?

    Physicist Hans Mueller once remarked that something does not exist until it can be measured quantitatively. This remark, made when I was an undergraduate more than 50 years ago, left a lasting impression on me. I try to be very careful to include the quantitative reasoning for any of my conclusions.

  • Vooch

    live load shouldn’t Be more than for a Office Building

  • sbauman

    How would anyone know without seeing the live load value (lbs/sq ft) for an office building? Also, what were the criteria used to derive this?

    These two items might shed light as to whether there is a substantive difference between bridge and office building live loads and why.

  • Vooch

    Recall it’s 40 or 50 PSF

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