L-Ternative Bridge is what is known as a pontoon bridge and would provide a temporary 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. Construction will only take 6 to 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 400,000 people use the L Train daily. Many people are concerned that in spite of solutions already proposed by the MTA, commuting between Brooklyn and Manhattan will still remain difficult.
Our current Kickstarter campaign 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.
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Why a pontoon bridge?
Pontoon bridges have been used for over a 1000 years and are still commonly used by militaries as a means of rapidly transporting vehicles and cargo across waterways. They are quick to assemble, cheap, and are capable of carrying large loads.
Here are examples of bridges used by the Chinese military which can be installed in less than 30 minutes.
L-Ternative Bridge Design
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.
How long will it take to cross?
At 30 mph it will take approximately 1 minute and 30 seconds to go from the Bedford Ave station to the Manhattan shoreline at 14th Street.
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.
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 cross streets in Brooklyn will be blocked off. In Manhattan, buses will enter onto 10th Street, turn north on Avenue C, and then turn west on 14th Street.
How will buses and pedestrians get across FDR Drive?
A temporary overpass will be built allowing buses to pass above FDR Drive so as not to interrupt the flow of traffic. 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 purpose built 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 many 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 could 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 would be to use suction embedded anchors, which are buried beneath the surface.
What About Shipping Traffic on the East River
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 and Army Corps of Engineers.