The idea of converting the existing Tappan Zee Bridge into a greenway or walkway — much like the former Poughkeepsie Bridge-turned-Walkway Over the Hudson — has been floated for some time by Greenburgh town supervisor Paul Feiner.

During his cabinet meeting yesterday, Governor Andrew Cuomo said the potential of preserving the bridge as an elevated walkway for cyclists and pedestrians is exciting. It is also a move that could save the state $150 million by avoiding demolition, according to Thomas Madison, the executive director of Thruway Authority, and could very well become a popular attraction much like the High Line.

No details on possible costs of the bridge conversion have been shared, and as the state continues to examine the idea, the New York World wants to know: How would the costs of transforming the bridge and maintaining a Tappan Zee walkway compare to the economic benefits it could bring?

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What we found

Maintaining a bridge that’s only for pedestrian use is usually less costly than one that is meant for highway use, say experts. But that doesn’t mean that it is in any way cheap, or a purely cost-saving option as the non-demolition view might suggest – security and safety are just some of the areas that would need to be continually paid for. Preserving the existing Tappan Zee Bridge while building a new one would also mean doubling base operation costs and having to staff and keep up two large structures at one of the widest points of the Hudson river.

Each bridge’s maintenance is assessed individually depending on a number of factors, such as length and conditions of the structure, but since the Thruway Authority has yet to come up with calculations for annual maintenance of a greenway (“That is to be decided, it will be up to Governor’s office and public support and a bunch of other things,” said a Thruway spokesman) here’s a look at Tappan Zee’s closest model, the Walkway Over the Hudson.

The Walkway is jointly maintained by the state’s Parks Recreation & Historic Preservation agency and Bridge Authority – the former is responsible for the plants, benches and other park features, while the latter owns the land and structure that supports the deck, a number of piers, and does their own engineering inspections and analyses of the walkway. Park maintenance can vary according to amenities provided, so we’ll look at the costs behind the physical bridge structure: basic maintenance for the 1.25 mile Walkway is $2 million a year, including insurance, and $500,000 for basic inspections. This does not include necessary major repairs, which are paid for through additional capital funding.

“Because the Tappan Zee Bridge is about three miles long, there would be higher maintenance costs as a result than the Walkway,” said Jeffery Zupan, a senior fellow for transportation at the Regional Plan Association.

Currently, Tappan Zee as a highway bridge has an annual routine maintenance tag of about $13 million for daily wear and tear and excluding operation costs, which typically are the same for any bridge. Over the past five years, the state has also spent some $326 million in capital construction, mostly for the ongoing re-decking. It is still too early to tell how much smaller that figure would be if the bridge only catered to human traffic which puts “less demand, less stress in terms of both volume and weight” on the structure, said Bridge Authority chief of staff, John Bellucci. He cautioned, however, comparing the Walkway to Tappan Zee which is a much younger bridge and was never abandoned or burnt down like the Poughkeepsie Bridge.

“[The Tappan Zee walkway] will be great for tourism, for local businesses, for the economy,” wrote Paul Feiner, the Greenburgh town supervisor who first raised the idea of preserving the bridge, to the New York World. “This will be the best and most fun park in the world.”

But Zupan questions if the walkway conversion is worth the cost. Because of the length of the bridge, he contends, it would see fewer visitors than the shorter Walkway, which has some 500,000 annual visitors. This, in turn, could affect the business, tourism and economic impact in the surrounding regions and the state that Paul Feiner, has lauded as one of the advantages to a walkway. An analysis of the Walkway’s benefits include $15.4 million in direct spending by non-local users, 383 new jobs and $9.4 million in new wages.

Rick Bell, the executive director of the American Institute of Architects‘ New York chapter, says that once the walkway is built, maintenance costs would be “negligible.” There are immeasurable benefits to be gained from the walkway conversion, says Bell: “To take the Tappan Zee as a connection between places that are only connected by vehicles and to make it into a place that can stop and experience the river – the idea of being able make it both recreational and non-polluting, is spectacular.”