Reconstructing a Better Tappan Zee Bridge in New York

For the first time in over 50 years, New York is building a new bridge, and it’s set to be one of the widest bridges in the world. Following more than a decade of delays, construction is finally underway to replace New York’s Tappan Zee Bridge, a bridge that was meant to handle a maximum of 100,000 vehicles yet has 138,000 pass over it every day. The Federal Highway Administration has deemed it a fracture critical bridge, and repairing it would have cost over $3 billion over the next 20 years.

 

 

 

 

 

 

 

 

New Bridge Technology

Two parallel spans will make up the new bridge with a 40-foot gap to accommodate a potential future commuter rail. When complete, the combined breadth will be 223 feet. If a rail line is added to the bridge later, the top towers would be joined at the top to support the additional weight. To stabilize the bridge, construction crews on barges use huge vibrating hammers to drive steel piles into the bottom of the Hudson River. Crews have also enlisted the help of an enormous crane, the Left Coast Lifter, which helped repair part of the San Francisco-Oakland Bay Bridge after earthquakes in 2009. It is one of the largest floating cranes in the world and has a lift capacity of 1,900 tons.

Key Design Elements

• Built to last 100 years without major structural maintenance
• Meets or exceeds all environmental standards
• Fewer piles and quieter vibration techniques mean less construction noise
• Construction due for completion within five years and 2.5 months

What the New Bridge Means for New Yorkers

For New York motorists, the new bridge promises less congestion, thanks to eight traffic lanes, four emergency lanes, new traffic monitoring systems, and a dedicated commuter bus lane. The northern span of the bridge will even have a path for cyclists and pedestrians. In the meantime, Tappan Zee has promised nearby residents that there will be less construction noise because the bridge design requires fewer piles and workers plan to use quieter vibration techniques whenever possible.

 

 

 

 

 

 

 

Environmental Concerns

Not only are loud construction sounds annoying for neighbors, but they also pose serious environmental hazards to two endangered species that live in the Hudson River. Scientists fear that strong sound waves from bridge construction will disturb the swim bladders of endangered Atlantic sturgeons and shortnose sturgeons, which can result in hemorrhaging and death. To limit the devastating effects on these fish species, steel piles are wrapped in enormous bubble curtains as they are being pounded into the ground beneath the river.

The first span of the new twin-span bridge is scheduled to open in 2016 and the full bridge should be complete by 2018. The total cost of the bridge project is $3.9 billion, which is actually far less than initially expected. To keep up with recent progress about New York’s new bridge construction, follow New York State’s Update Blog via RSS feed or Twitter.

Photo credit: D. Robert Wolcheck and mak506 via Flickr