How tall is this fence? What about those short cross-bars at intervals? Won’t those make convenient places to throw a grappling hook? And what happens when the steel begins to rust and weaken? Won’t the spaces allow incendiary stuff to be thrown into the U.S., start fires and stuff? Can’t the illegals use the same sort of climbing loop that people going up telephone poles use?
These new bollards in San Diego/Tijuana are eighteen footers - taller pieces are used on steeper slopes (up thirty feet). A second barrier will be built behind this one, which will be thirty foot tall its whole length. The space between the barriers (enforcement zone) is kept clear of vegetation, so there is minimal fire risk around San Diego. In many areas of the border, there will just be a single bollard barrier - but there has never been a big arson threat so far.
The short cross bars are only temporary braces, till the concrete foundations cure. The steel is a special formulation (Cor-Ten), that forms a protective surface rust, which actually seals it from corrosion. The bollards are filled with concrete, which keeps rainwater out, and greatly strengthens the structure. Cor-Ten structures in less favorable environments are in good shape fifty years later.
The 5-6 inch spaces between bollards can allow some things to pass through, but they are highly desired by Border Patrol. They allow Officers to see what is going on over the other side. They can issue verbal commands, photograph, pepper spray, tase, or even shoot in self defense. Cameras with night vision are used to monitor and record, 24x7. Officers detect activity much earlier with see through barrier, and have more time to respond. It provides bad guys no cover for attempts to dig under or cut through, and the huge ladders that would be needed can be seen coming from far away.
Tree/pole climbing harnesses can be used on bollards (some people can climb Mount Everest with ropes and ladders). The anti-climb plate at the top presents a difficult obstacle to that approach however. The military deployment to the border (which has been extended through at least September) has mounted rolls of concertina along the back side (American side) of the anti-climb plates around some of the Ports of Entry. This has so far proven to be very effective at stopping those who do get to the top (usually by ladder). It is too high to jump, and the concertina is shielded from cutting behind large solid steel plates. DoD has announced that the Military deployment will install 150 miles of concertina between Ports of Entry, so some of that may be reinforcing bollard barrier in high traffic areas.