If elected President of the United States, Donald Trump wants to build a wall along the
country’s southern border with Mexico. So is it actually possible to build a wall like
that and what would it mean for the construction industry? We take a look.
The US international border with Mexico stretches 1,989 miles from the Pacific across to the
Gulf of Mexico. Fencing of the border began back in 1990 but was expedited after 9/11
with the passing of the 2006 Secure Fence Act. Since then, more than USD $7BN have been
spent on fencing along 653 miles of the boundary.
That fencing varies between different parts of the border. In easy-to-access urban areas
a 5.4m high steel barrier is used, whilst lower key "vehicle fencing" has been installed
in more remote portions that are considered to be low-risk.
Vast stretches of the border are formed of natural barriers – such as the Rio Grande
River – and much of it passes through remote terrain – the deserts of Arizona and the
mountain ranges of New Mexico. In the dunes in Southern California, a "floating fence"
had to be built to allow for the natural movements of the sand.
In the primaries, Donald Trump stated that he wanted to build a 2,000 mile wall, but
that has since been reduced to 1,000 miles in recognition of the natural barriers that
exist. While the proposed wall has got shorter, it grew in height over the course of a Twitter
argument and is now somewhere between 10 and 12 meters tall.
Trump believes the wall will cost USD $8BN but we’ll come back to estimates a little
bit later on.
He plans to make Mexico pay for the wall by blocking the flow of payments from Mexican
Nationals working in the US back to Mexico. That equates to about USD $24BN each year.
That cut off will, on Trump’s logic, force Mexico into making a relatively small financial
contribution to the wall, in order to release the much larger payments from their Nationals.
So what would Donald Trump’s wall actually look like? Well a team at Alliance Bernstein
did some excellent research on this.
They assumed a wall length of 1000 miles, a height of 12 meters (with an additional
two meters of wall below ground to deter basic tunnelling) and a thickness of 250mm. They
also assumed that a 1.5 meter wide, 300mm deep concrete strip footing would be required
along the entire 1,000 mile length.
Of the many materials available, several structural engineers have agreed that pre-cast concrete
is preferable, particularly given the high temperatures along the border that would preclude
the use of a poured in-situ concrete solution.
Based on these parameters, the wall would require 7.1 million m3 of concrete and 2.4
million tonnes of cement, assuming a standard content.
But the wall would not look the same along its length. Bespoke engineering may be needed
to deal with specific geographic features and allowances must be made for flooding as
the border crosses numerous floodplains.
The construction complexities don’t end there. The formation of a more substantial
barrier than exists at present would require access roads to be built – which isn’t
simple on a mountain range or in a remote desert. The border also passes through Indian
Territory, wildlife reserves and private ranches whose owners would have to agree to sell their
land to the federal government.
Delays, surging costs and disputes with private land owners were all encountered during construction
work of the relatively modest existing fencing.
At this stage putting a figure on a project like this is not easy. The consensus among
experts is that to construct the sort of thing that the Alliance Bernstein have assumed would
cost at least USD $15BN and even as much as USD $25BN.
Whilst those figures may sound enormous, you need to keep in mind that the current US federal
budget is just under USD $4TN.
Back in 2009, the US Government Accountability Office (GAO) said that the basic costs of
building a mile of fencing averaged between USD $2.8M and $3.9M in the easy-to-access
metropolitan areas. This rose as high as USD $16M per mile in desert or mountain regions.
You then need to factor-in the costs of design, land acquisitions, environmental impact statements,
transporting materials, labour, site setups and accommodation. Once built, the costs of
ongoing guarding and maintenance also need to be considered.
The progression of such a project would be big for the construction industry. Some of
the largest value schemes on site at present include the USD $20BN Crossrail scheme in
London, the USD $5.25BN expansion of Panama Canal and the USD $11BN Jubail Industrial
City Two in Saudi Arabia – so Donald Trump’s wall would be right up there.
If he were elected and if proposals passed Congress, planning and design work for the
wall could start coming into the industry in 2017, with construction works perhaps commencing
the year afterwards.
Experts believe the wall could create as many as 100,000 jobs and given the financial pressures
of transporting pre-cast concrete and cement over great distances, local manufacturers
of those materials could stand to gain. Alliance Bernstein calculated that the wall could add
1.1% to US cement demand in both 2018 and 2019, which would be huge for an industry
that currently grows by 4-5% each year.
Of course, if Mexico were begrudgingly paying for the wall they would be unlikely to use
US suppliers and that is perhaps vice versa for the United States.
We will leave debate about the rights and wrongs of building a border wall to others.
But we hope this has helped to put a bit more substance behind a key US Election issue.
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