Project image
pledged of $50,000pledged of $50,000 goal
Funding Unsuccessful
The project's funding goal was not reached on Fri, March 16 2018 6:28 PM UTC +00:00
Last updated March 16, 2018

L-Ternative Bridge

Building community support for a pontoon bridge providing transit between Williamsburg and Manhattan during the L train shut down.

L-Ternative Bridge

Building community support for a pontoon bridge providing transit between Williamsburg and Manhattan during the L train shut down.

pledged of $50,000pledged of $50,000 goal
Funding Unsuccessful
The project's funding goal was not reached on Fri, March 16 2018 6:28 PM UTC +00:00
Last updated March 16, 2018

What is a prototype?

A prototype is a preliminary model of something. Projects that offer physical products need to show backers documentation of a working prototype. This gallery features photos, videos, and other visual documentation that will give backers a sense of what’s been accomplished so far and what’s left to do. Though the development process can vary for each project, these are the stages we typically see:

Proof of Concept

Explorations that test ideas and functionality.

Functional Prototype

Demonstrates the functionality of the final product, but looks different.

Appearance Prototype

Looks like the final product, but is not functional.

Design Prototype

Appearance and function match the final product, but is made with different manufacturing methods.

Production Prototype

Appearance, function, and manufacturing methods match the final product.

Project supporting material callout image

Prototype Gallery

These photos and videos provide a detailed look at this project’s development.


L-Ternative Bridge is what is known as a pontoon bridge and would provide a solution for rapidly transporting people between Brooklyn and Manhattan while the L Train is under repair. It would be capable of supporting two lanes for bus traffic and two walking/bike paths. Early projections suggest that construction could be completed in about 8 months and the costs can be completely covered by a $1 toll. 

Right now over 225,000 people use the L Train to commute across the East River and many are concerned that, in spite of solutions already proposed by the MTA, commuting between Brooklyn and Manhattan will still remain difficult. 

"I Like this idea of a pontoon bridge over the East River. If you want to see NYC consider creative options like this, go to Kickstarter and back this project"

Fred Wilson - Founder of Union Square Ventures

What will be accomplished in this initial stage?

The main purpose of this stage is to demonstrate community support and provide the city with a detailed and actionable plan. This plan will include bids on all material and labor costs. We will also conduct an analysis of the impact on east river maritime traffic and seek Coast Guard approval of the design in accordance with the General Bridge Act of 1946. Ideally the MTA will either use the plans and contractor recommendations we provide to build L-Ternative bridge, or they will establish a public-private partnership with a developer who is capable.

*If the bridge is not built we will return all funds not directly spent on design, planning, and feasibility analysis (not including the commissions taken by Kickstarter). Funds will be returned proportionately, based on the amount given. We are currently exploring the possibility of appointing a community based 501(c)(3) as a fiscal agent. They would agree to provide financial oversight and transparency on behalf of our backers.

Why a pontoon bridge?

Pontoon bridges have been used for over 1,000 years and are the most rapid and affordable way to build a bridge over a large body of water. This bridge was assembled by the Chinese military in under 30 minutes. 


How much will it cost?

We have not yet received bids, however, the bridge below is very similar in design, almost twice as long, and was built by a consortium of European companies for only $38M in 2008.  It includes an elevated section for smaller maritime traffic to pass through (ferries and private boats) and a 230 foot wide retracting section for larger ships. 


Elevated section for ferries and smaller boats
Elevated section for ferries and smaller boats

Although L-Ternative bridge will only be about half as long, construction costs have gone up considerably since 2008 and our design also includes two additional lanes for pedestrians and bicyclists. 

We are currently receiving cost estimates from contractors and will publish these in the coming weeks. 

How long will it take to cross the bridge?

At 30 mph it will take approximately 1 minute and 30 seconds to go from the Bedford Ave station to the Manhattan shoreline. 

How do you rapidly transfer people from the subway to buses?

In order to move people as quickly as possible from the subway and into buses, a partially enclosed bus terminal could be constructed on 7th Street between Bedford Ave and Driggs Ave. Turnstiles would remove the need for people to swipe their metro cards as they board the bus and expedite the process. This could be accomplished while still preserving sidewalk access for businesses and residences.

Bus Station
Bus Station

 What route will buses take?

Buses would enter Brooklyn via 7th Street, turn North on Driggs Ave, and then head back to Manhattan via 8th Street. Through traffic on all cross streets in Brooklyn will be blocked off.

In Manhattan, buses will enter via 10th Street, turn North on Avenue C, and then run along 14th Street to the west side highway. 

Bus Route
Bus Route

How will buses and pedestrians get across FDR Drive?  

A temporary overpass will be built over FDR Drive allowing buses to cross without interrupting the flow of traffic. This will be built using the same Bailey Bridge design that is used on the pontoon bridge and can be erected in several days. 

There is already an overpass in place for pedestrians on 10th Street.  

How will the pontoons be made?

The pontoons will be 90-foot long deck barges. It will take 30 to span the 2,600 feet across the East River.

How will the road and walking paths be made?

There are several companies that sell or lease temporary modular steel bridges. These can be rapidly assembled to obtain any length due to their modular design. The type that will most likely be used is called a Bailey Bridge.  It was designed in WWII and is still widely used throughout the world.  Hundreds of feet can be assembled per week and it doesn't require any welding or skilled labor to build.  

Where would the bridge be assembled?

There are a number of potential construction locations along the north and south sides of Newton Creek. The bridge would be made in modules. Each module would be floated from the construction site into position, anchored and connected to the rest of the bridge.

How do you keep the bridge from moving?

The bridge will be anchored in place using 3,500lb. Delta anchors. These anchors work very well in mud bottoms like the one in the East River. Another option if these anchors prove to be insufficient are suction embedded anchors that are implanted beneath the seabed. 

What will be done with any extra money that is raised?

Extra money raised will only be spent if it will help bring about the construction of the bridge.  If the project is deemed to be infeasible at any point, all unspent money will be returned to backers. As mentioned above, we are currently seeking a local 501(c)(3) to act as a fiscal agent that would provide financial oversight and transparency on behalf of our backers.

What about the legal hurdles and maritime traffic? 

Section 9 of the Rivers and Harbors Act of 1899 and the General Bridge Act of 1946 placed the navigable waters of the United States under the exclusive control of the U. S. Coast Guard to prevent any interference with their navigability by bridges or other obstructions except by express permission of the United States Government. The purpose of these Acts is to preserve the public right of navigation and to prevent interference with interstate and foreign commerce.

We believe that a 240-foot wide drawbridge for larger ship traffic and a permanently elevated section for ferries and smaller boats, may provide a sufficient solution for the passage of maritime traffic.  More research is necessary to validate this hypothesis. We are currently reviewing data provided by the US Coast Guard, Army Corps of Engineers as well as AIS ship tracking. 

Further Reading:

In the News

Spectrum News NY1

Curbed NY



Risks and challenges

U.S. Coast Guard permit approval may not be granted. Section 9 of the Rivers and Harbors Act of 1899 and the General Bridge Act of 1946 placed the navigable waters of the United States under the exclusive control of the U. S. Coast Guard to prevent any interference with their navigability by bridges or other obstructions except by express permission of the United States Government. The purpose of these Acts is to preserve the public right of navigation and to prevent interference with interstate and foreign commerce.

We believe that a drawbridge for larger ship traffic and an elevated section for ferries and smaller boats, may provide a sufficient solution for the passage of maritime traffic, however more research is necessary to validate this hypothesis.

City support might not be obtained.

The MTA may not honor the rewards offered in this campaign to our backers.

The bridge may not be capable of meeting regulatory requirements.

Pontoon bridges are more susceptible to damage from storms and tidal surges.

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Questions about this project? Check out the FAQ

Funding period

- (30 days)

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