During last year's US presidential election, Donald Trump bragged, "Nobody builds walls better than me." The former real-estate mogul went on to promise: "And I will build them very inexpensively." Now, as president, he wants to act on those bold claims.

The race to build the wall along the United States' border with Mexico will start on March 6: At that point contractors can submit design plans to the Department of Homeland Security on the agency's homepage - contracts are to be awarded in April, and the wall finished two years later. Depending on what day it is, Trump has said that the wall will be anywhere from 10 to 30 meters (33 to 100 feet) high. The only thing that is certain at this point: "It will be a wall, not a fence."

There is certainly no lack of bidders for the enormous project. US news channel CNN has reported that more than 300 companies have already voiced interest. Yet, major international companies have shied away from it for one clear reason - they fear that being associated with Trump's isolationist policies could damage their reputation.

Others have been less unequivocal. On the morning after Trump's election, Bernd Scheifele, CEO of Germany's Heidelberg Cement, was quoted in several media outlets as saying that his company's "cement factories in Texas and Arizona" were ready to help build the wall. When DW contacted Heidelberg headquarters about the statement, it was told that the words had been taken out of context. A spokesperson explained that the company has a decentralized organizational structure and that "assessments and decisions, in this instance, will be left up to American management." That does not sound like a strong disclaimer.

Mexican cement?

Reactions from LafargeHolcim, the world's largest building-materials manufacturer, were similar. When asked about the wall by the business newspaper "Handelsblatt," CEO Eric Olsen said that LafargeHolcim wanted to be involved in all major US infrastructure projects. As the largest cement producer in the USA, the company routinely assesses potential projects. 

Nevertheless, no one at the Swiss company's headquarters seems willing to give a binding statement. "An interview is not possible at the moment," was the answer DW received in response to an interview request. Lafarge's e-mail reply simply stated, "The US government, including Homeland Security, is a LafargeHolcim customer."

The only company that has clearly distanced itself from the project thus far has been German-based Hochtief. Paradoxically, the Mexican global player Cemex, the world's second largest producer of building materials, has been very clear about its interest in the project. "When someone asks us to quote a price, we are happy to do so," as Chairman Rogelio Zambrano Lozano told the Mexican newspaper "Reforma."  

Unrealistic costs

Watchtowers, flood lights, motion detectors, razor wire, infrared cameras, drones - the list of equipment for such a wall is long. And it is cost that will play the biggest role in the tender process. According to Trump, the total cost for building the wall will be around $10 billion (9.4 billion euros).

But analysts from AllianceBernstein (AB), a financial research firm, presented a study in July 2016 projecting that the wall would cost between 15 and 25 billion dollars. AB's analysis was based on a 45-foot-high wall (12 meters). Due to high temperatures in desert areas, analysts recommended using cement modules, like those the Israeli government has been using on the West Bank. AllianceBernstein's cost analysis did not include maintenance and operating costs.

Some of it is already there

The Trump administration is not starting from scratch with the project. Bill Clinton erected the first sections of fence in the southwestern US in 1994. After the attacks of September 11, 2001, George W. Bush pushed forward with the project. Since then, the 1,100-kilometer (684-mile) fence - which runs along a border with a total length of 1,989 miles - has been outfitted with sections of concrete wall, steel beams and other obstacles. AllianceBernstein says that the existing wall has cost taxpayers some $7 billion.

AllianceBernstein estimates that Trump's wall will cost far more - especially since many sections of the border are very difficult to reach with heavy equipment. Additionally, Trump wants to increase the number of agents patrolling the border. Current 21,000 security agents monitor the border - another 5,000 are to be added.

Maybe just a fence in the end?

President Trump wants Mexico to pay for the wall. But the Pena Nieto government in Mexico City has flatly rejected such demands. Trump is also contemplating extra taxes - for instance on cross-border money transfers - as a way to make Mexicans foot the bill.

But first, American taxpayers will have to fund the mammoth project. In a January television interview, House Speaker Paul Ryan, a Republican, confirmed that Congress would initially cover building costs. At the time, Ryan spoke of total costs of between 8 and 14 billion dollars.

Even Secretary of Homeland Security John Kelly was careful in his choice of words when addressing Congress, speaking of a physical barrier rather than a wall. Trump's "great big, beautiful wall" could well devolve into a fence.

No doubt the US president would quickly find a way to justify the change in plans though - after all, he did promise to create thousands of new jobs for the US steel industry.