those scooters just have too limited a range. But am I correct that initially there were no signs stating no trespassing? Were there any fences or other items to keep back non workers? Was there any evidence that the owners were attempting to recover thechips and tokens?

I ask this because I was under the impression that (until the no trespassing sign was put up) there was no effort on the part of the landowners to restrict access to their property. I am also under the understanding that these chips and tokens were tossed into a hole and covered with cement (or in some way mixed with cement). In Lieu of some notice that the chips and tokens were not in fact abandoned property, a reasonably prudent person could only presume the obvious, the chips and tokens were abandoned property.

I suspect the no trespassing sign is related much more to the concern that a digger might get hurt thn they are absconding with chunks of concrete containing chips. If there are heavy machinery located there, protecting them from goofballs is certainly a priority also.