Border tunnels often uncovered by luck
Here is one of scores of news clippings reporting the border tunnel situation:

![Instruments are too imprecise, [USBP] officials say](/_assets/img/USBPInstrumentsTooImprecise.jpg)
One cross-border tunnel was discovered by chance a week ago. A bus drove over a sinkhole in a road running along the border fence near the San Ysidro crossing and investigators discovered a dirt-filled bucket inside.
Another tunnel was found Wednesday by crews intent on filling the first.
The discovery of such tunnels from Mexico is rising — nearly as many have been found in the past 3½ years as in the 11 years before.
But the increased numbers aren’t the result of a concerted effort to ferret out those who would use underground passages to sneak drugs, people, or who-knows-what into the country.
It’s come to a point where the agents are obligated to look for any evidence that something might be transpiring beneath them,
said Angel Santa Ana, a Border Patrol spokesman.
But agents don’t have Superman-like power to see what lies underground, and they don’t have the technology, either, he said.
There are several private companies who are developing this technology and are testing it,
Santa Ana said. For now, we have to resort to the agents in the field doing their jobs, being vigilant, and looking for any kind of evidence above ground.
[…]
Source: Onell R. Soto, San Diego Union-Tribune