A couple decades ago detector loops (wires in pavement) were sealed into their sawed slots with epoxy.  About 10 or so years ago the industry changed to asphaltic emulsion sealant.  Why the change?   It turns out that pavement wears down with time but epoxy does not.  So as pavement ages, epoxy would stick up.  As pavement ages more, the epoxy would break loose, and the wires would pop up out of the sawed slot and eventually break from the tire strikes.  The photo shows sawed slots, empty saw...
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