The flat robot hummed unheard as it ran along the rails of the sub-highway service plenum, gliding smoothly to a stop at the location of the damaged slab.  The plenum was clear; no need to move fragments out of the way before doing the replacement.

Clunk.  The pneumatic prop-ram extruded from above and below, pressing against the damaged surface slab and the ground alike, enough to take over the support of the highway and the vehicles on it while the slab was unsealed from the surrounding framework.  The robot paused momentarily, communing with the road-grid control center…

The wheelspheres of one groundcar had barely left the slab when it dropped down under the road, the prop-ram venting, only to be abruptly shoved aside by the loader, dropped into a waste hopper and replaced on the prop-ram by a clean replacement, this in turn slammed up into place by new air just in time for the wheelspheres of the freight wagon following to cross onto it.  Moments later, a hiss of active nanosealer sealed the new slab in place.

Job number HW-112-0000188 complete; no delays.  Proceeding to next job.