The mililary needs some material that can be crop dusted onto road
beds that can only be disturbed by digging and not by vehicle traffic.
The material must be deposited with a characteristic "thumbprint" that
can be identified with the appropriate sensors but cannot be
duplicated, i.e., it cannot be swept up and spread over a freshly
This method wouldn't reveal the old bombs but it would make it easy to
spot where a roadbed was recently dug up.
Ordinary traffic performs a certain amount of "gardening" on a dirt
road, meaning some of the taggant _will_ be mixed into the roadbed
material. How deeply depends on the exact nature of the material (sand/
clay/organic dirt, salts, concrete, asphalt, etc.) the kind and degree
of traffic, the weather _and_ climate, and so on.
Worst case you get washboarding which requires periodic repair,
meaning deeper penetration by the taggant. It will however be more
evenly distributed than the sort of localized dugskullery you're
Hence the sort of disturbance due to traffic will be easily
differentiable from that due to digging.
Just off the top of my head, how about microscopic polymer chips
like those used in dynamite. Rather than the complex layering used to
indicate batch numbers etc. it would be infused infused with an
additive which, when exposed to UV, fluoresces in the IR, not the
visible. If laid down by ground vehicle or say Predator or other drone
during low traffic periods it would have a fairly even characteristic
distribution, and any disturbance will be immediately visible by
inspection by personnel wearing IR goggles during the day, and at
night with IR goggles and the assistance of a UV lamp. Inspection
could also be done by suitably-equipped drones of course.
Attempts to "sweep up" and use the dust to cover new bombs will not
replicate the dust distribution as laid down originally.
Mark L. Fergerson
Emplace dense minefields under the road and to both sides. Allied
vehicles dynamically inert the mines with a short-range rolling
encrypted digital signal. Everybody else enjoys virgins FOB allah
("Santized For Your Protection")