No one has figured out how to do it. Money is one reason, but it’s also very hard.
“CBP suspended its efforts to measure the contributions of border fencing to border security in 2013 due to sequestration related funding shortfalls,” GAO said.
But even if money were not an issue — and it always is — sorting out the individual effectiveness of parts of an interrelated system that includes law enforcement officers, surveillance technology and other infrastructure is not easy.
“Developing metrics for a single element of this system is challenging,” GAO wrote.
CBP does gather some useful information, including “data on apprehensions, turn backs, got aways, and drive throughs, and border fencing, by type and design.”
The agency could use that “to develop metrics that compare estimated known illegal entries before and after fence construction. CBP could also use these data to help determine the extent to which border fencing contributes to diverting illegal entrants into more rural and remote environments as well as border fencing’s impact on apprehension rates over time.”
But it doesn’t.
“CBP has not developed metrics that systematically use these data, or other available information, to assess the contributions of border fencing to border security operations along the southwest border,” according to GAO.
Despite the lack of an overall assessment, CBP officials have identified benefits of pedestrian and vehicle barriers. The 654 miles includes 354 miles of primary pedestrian fencing and 300 miles of primary vehicle fencing. Primary refers to the fencing closest to the border. In some areas, there are second and third rows of fences.
Fencing is not cheap.
“From fiscal year 2007 through 2015, [CBP] spent approximately $2.3 billion to deploy border fencing along the southwest border, and CBP will need to spend a substantial amount to sustain these investments over their lifetimes,” GAO said, citing CBP figures.
Trump’s wall could cost $10 billion or more, money he imagines Mexico will pay.
“By constructing pedestrian fencing in more populated urban environments, Border Patrol officials stated that [the Department of Homeland Security] intended to divert illicit cross-border activities into more remote or rural environments, where illegal entrants may require hours or days to reach the nearest U.S. community,” the report said.
The safety of border patrol agents is improved with “modern style pedestrian fencing [that] reduces illegal entrants’ ability to stage mass crossings, which can overwhelm agents and jeopardize agents’ safety,” GAO added. Also, two years after modern bollard pedestrian fencing was installed, assaults on Border Patrol agents at the Nogales, Ariz., station dropped by 81 percent.
Officials also said vehicle fencing is effective in reducing illicit trafficking in rural areas.
But fences have their limitations, especially the older, weaker models that are easier to cut.
“Illegal entrants breached legacy pedestrian fencing at an average rate of 82 breaches per fence mile,” GAO reported, “compared to an average of 14 breaches per fence mile of modern pedestrian fencing.” That is still a lot of cut fences.
Even vehicle fencing can be defeated by determined and inventive border crossers.
“Agents we spoke with in the Tucson sector,” the GAO report said, “told us they have witnessed illegal entrants attempting to use ramps to drive vehicles up and over vehicle fencing.”
CBP agreed with GAO recommendations to develop metrics and use them when making resource allocation decisions.
“Tactical fencing provides a persistent method to impede illegal cross-border activity,” said a Department of Homeland Security letter included in the report, “which offers Border Patrol agents additional time to respond to and resolve threats.”