As I posted earlier, if there were even relatively small quantities of explosive used, everyone in the vicinity could smell it.
They also have constant running traffic cams in that area which I am sure are being gone over as we type.
“Some bomb components are more odoriferous than others. C-4 has an incredibly strong scent; it’s followed in decreasing order of smelliness by dynamite, TOVEX, detonating cord, and TNT.”
And then there are the explosives that only sensitive dog noses can detect.
Anyone see any hound dogs sniffing around near the bridge?