Apparently this is pretty common everywhere nowadays because of theft and liability type issues.
But I think every situation is different, and there CAN be different "possible time frames of permission", depending on where they are in their construction progress. I think you gotta play it by ear, and see how far you get sometimes.
Most likely, the time you CAN detect, is immediately after they're done clearing an area. But once they bring in their big toys, and building materials, they don't want you near them.
There was, and still is, a MAJOR project going on near me, taking place in what's regularly a PUBLIC park, and a PROVEN hotspot for old coins. This particular site had the "Authorized personel only" signs around it. So I went and spoke with the crew about detecting, and they told me to "Have a blast, but just wait till after 5 when we leave". Then sure enough, after 5pm, I'm in there swinging, and 3 cop cars pull up, (Yes, with lights on!) to see what I'm doing. Of course they never saw a Lesche before either! I told them I was metal detecting, and looking for old coins. I showed them the 2 Injuns I had just found. They looked at me like I was from Mars, and just wanted to check my ID. (These cops are used to serious drug related crime in this particular area). Then I explained to them that the crew gave me permission, but not till after 5. So the cops tell me that I'm not aloud in there on "their time" now. "If the crew lets you detect while they're here, that's fine, but not after 5".
Anyway, the progress of this particular project is so far along now, (and now they've layed down about 3 ft. of this shale-like stone everywhere), that I've long since given up. Those coins are gone to history.
On the other hand, I've had several GOOD construction site experiences also. I've gotten some YES's in construction zones where they've just cleared everything, and everything's fairly smooth, and it's very unlikely that you can fall, trip, or hurt yourself in any way. And since it's already dug up, there's NO WAY you can mess anything up that they're doing. Got a lot of good coins, and infomation about other upcoming projects, and locations of their dirtpiles that I can hunt.
So alot of times you just gotta improvise, and play it by ear as you go along. Things can change on a daily basis, depending on who you talk to.
All you can do is be REALLY nice to everyone. And WHENEVER someone gives you a YES, MAKE SURE YOU REMEMBER THEIR NAME! Because you WILL be using it as soon as someone gives you a hard time again! lol!
Let THEM have a power struggle over it!
This is all just my opinion of course.
Wow, sorry for the long post/semi-rant. H.H.
