President Donald Trump (C) is shown border wall prototypes in San Diego, California on March 13, 2018. Mandel Ngan | AFP | Getty Images

President Trump claimed this week that his long-promised wall — the solution for what he describes as an illegal immigration crisis at America's southern border — would be "finished" in just two years' time. But it's more likely to take years longer than that, construction experts say. Trump tweet: BUILD A WALL & CRIME WILL FALL! This is the new theme, for two years until the Wall is finished (under construction now), of the Republican Party. Use it and pray! A bitter fight over that proposed barrier along the U.S.-Mexico border has led to a record-breaking government shutdown, which has now stretched well into its second month. The latest attempts to reopen the government failed in Senate on Thursday.

The acrimonious negotiations on Capitol Hill have centered around whether a spending package to reopen nine federal agencies should include billions of dollars to fund a border barrier. Democrats have held firm against providing any money for the wall, and have called on Trump to reopen the government and continue border security negotiations separately. Trump is demanding $5.7 billion in border wall funding before ending the shutdown, arguing that the so-called crisis cannot be ignored or delayed. Trump has even threatened to declare a national emergency in order to sidestep House Speaker Nancy Pelosi, D-Calif., and Senate Minority Leader Chuck Schumer, D-N.Y. One expert, however, recently estimated that it could take 11 years for 10,000 workers to build 1,000 miles of steel border barrier, a length Trump had called for on numerous occasions during the campaign. Ed Zarenski, a construction economics analyst with three decades of experience as a building projects cost estimator, said he arrived at those figures by first approximating the total cost of various materials involved, such as concrete, steel and temporary roads. He estimated that it could cost $22 billion to cover the whole project — a number he admits is likely "much too optimistic" because it excludes factors including inflation, workers' accommodations and land acquisition.

A construction crew works on replacing the US-Mexico border fence as seen from Tijuana, in Baja California state, Mexico, on January 9, 2019. Guillermo Arias | AFP | Getty Images

He then calculated labor and time, based on what he says is an industry rule of thumb that it takes 5000 to 6000 workers to build $1 billion worth of construction in 1 year. Adding more workers to Zarenski's formula would shrink the estimated construction time. But Zarenski notes that finding the available workers and materials, distributed over potentially dozens of job sites along the border, would quickly become unrealistic. "Availability of labor is an issue right now," Zarenski said. Caroline Clevenger, a construction engineering and management professor at the University of Colorado, said a rough construction rate of two miles per week was a reasonable estimate for Trump's barrier. She also referenced another border fencing project that took place in El Paso, Texas, in 2009. Reports at the time that structure was built say the "Border K Fence" stretched just 38 miles, cost $170 million (nearly $200 million in today's dollars) and involved 1,100 workers. That fencing also stood at just 19 feet high, significantly shorter than some of the 30-foot replacement border barrier that has been built since Trump was elected. Like Zarenski, Clevenger said that the logistics of getting workers and materials stretched across the border would likely pose the biggest obstacles to building a wall quickly. "You have to move people there. You have to make sure they have housing," Clevenger said. "It's not as if we're producing something in a factory."

Wall to wall

The $5.7 billion that Trump has been fighting for would only be enough to build a fraction of the wall — about 234 miles of new steel barrier, according to a Jan. 6 letter from the Office of Management and Budget. It's hardly enough to plug every hole, as Trump has recently said is required for a wall to be effective. "We can't let [there be] gaps," Trump said at the White House in early January. "Because if you have gaps, those people are going to turn their vehicles, or the gangs — they're going to [be] coming in through those gaps. And we cannot let that happen." To be sure, Trump had also proposed less than two weeks beforehand that perhaps only 500 to 550 miles of new or replacement barrier were necessary. The Trump administration currently says that roughly 762 miles of new or updated barrier are needed along the 1,954-mile-long border, according to a department official, who requested anonymity. Zarenski said that the 1,000-mile estimate he used could be re-proportioned to match the DHS' 762-mile figure. That would clock the construction of the wall closer to eight years. It was unclear which measurement Trump was referring to when he tweeted Wednesday that the wall will be "finished" in "two years." Trump's claim was "just ludicrous," Zarenski said, no matter which measurement one assumes Trump to be referencing.

Migrants from Honduras, part of a caravan of thousands from Central America trying to reach the United States, climb a border fence to cross illegally from Mexico to the U.S., in Tijuana, Mexico, December 21, 2018. Mohammed Salem | Reuters