Gov. Andrew M. Cuomo predicts that the replacement of the Tappan Zee Bridge will generate some 45,000 badly needed jobs for the Hudson Valley during the five years it's under construction.
Transportation experts say such projections are rooted in an inexact science, where the variables are always changing and much hinges on how you define a job.
The experts agree that, no matter how the numbers are sliced and diced, the building of the bridge will create many thousands of jobs. Possibly fewer than the governor's office is claiming, but possibly even more, they say.
"When you create an economic model it's just that, a model of reality," said David Ellis, a researcher at Texas A&M's Texas Transportation Institute. "You're trying to estimate. It could be 45,000 jobs. It could be 36,000 or it could be 54,000. It depends on so many factors. But it's going to have an economic impact. There's no question about that."
Cuomo administration officials say the 45,000 figure, first put forth this summer, is an estimate based on a formula used by federal highway officials.
"While it is not possible at this time to know the precise number of construction-related and other jobs that will be created, we do know that the project will generate much-needed economic activity and create many thousands of jobs for local residents throughout the region," said Dan Weiller a spokesman for the New York State Thruway Authority, on Monday.
The cost for replacing the aging Tappan Zee could top out at $5.9 billion, but the final number won't be known until one of three consortiums on a short list of bidders is chosen to lead the project, a decision expected in the coming weeks. Even after plans firm up, though, it's unlikely there will be any hard numbers on job creation. Federal highway officials have taken care in recent years not to get into the business of predicting how many jobs a project can create.
Construction trade groups frequently cite a Federal Highway Administration estimate from several years ago, which suggested that for every $1 billion invested in bridge, tunnel or highway projects, some 28,000 jobs are created.
Of that, some 9,537 would go to on-site construction jobs, 4,324 to supplier industries like steel makers and an additional 13,962 to the rest of the economy.
The Federal Highway Administration itself no longer relies on those estimates.
In California, state officials estimate that for every $1 million invested in a project, 11 full-time jobs are created, according to researcher Essie Adibi, who heads the Gary Anderson Center for Economic Research at Chapman University in Orange, Calif.
Using that formula, the Tappan Zee Bridge project would generate nearly 65,000 jobs.
Construction jobs alone could number as high as 8,000 during the life of a project, said George Drapeau, vice president of the Construction Industry Council of Westchester and the Hudson Valley, a major proponent of the bridge project. But not all those workers will be on the job at the same time, Drapeau said.
Steelworkers and heavy-equipment operators will dominate the hardhat scene in the early years of the project, he said. In the end stages, craftsmen like electricians will move in to wire the bridge while the steel workers and heavy-equipment workers are off to the next job.
The further you go down the chain, the tougher it gets to predict job creation, the experts say.
Take the hypothetical sandwich shop that would open in Tarrytown to serve hungry bridge workers. The meat cutters and counter workers should be included in the job creation total because their jobs are directly linked to the bridge project, most experts agree.
But what about the bread deliveryman from Nyack, who has to add a few more loaves of bread onto his truck for delivery to the Tarrytown sandwich shop?
Or, further down the line, the Iowa farmer who grew the wheat that went into the hard-crusted roll for the roast beef sandwich ordered by a backhoe operator?
Even the experts readily concede that job creation can get a little complicated.
Ellis said such calculations -- if grounded in good judgment -- should reflect a straight line from the project to the job created. The bread deliveryman and the farmer don't count, he said.
"The effect gets less and less as you go down the line," Ellis said.
The most difficult part of the equation is estimating whether the project will benefit the local economy or some other state's economy, Adibi said. For instance, steel for the new bridge is expected to be shipped in from other states. Should the steelworkers' jobs in Pennsylvania be counted toward the projected job total for the Tappan Zee?
"You could be buying material that could be coming from Virginia or Ohio or somewhere else," Adibi said. "It's really helping some other region or county. That put a hole in their estimation. And that's always the pitfall with some of this. It's is not a perfect science."
But Adibi added that the 45,000 figure from Cuomo's office could very well be an accurate reflection of how many jobs will be created. The only true test will come when paychecks are actually issued, Adibi said.
"Their number is within the range," Adibi said. "I would not argue with that number."