Anyone ever use Promark II's on a concrete bridge?
While standing on the bridge today I noticed it vibrating up and down with the heavy traffic. I'm guessing it moved one or two millmeters.
The point I need to occupy is in the sidewalk portion, but it's integral with the deck.

1-2 millimeters comes out in the wash. As long as it is vibrating harmonically no problem.

Last year I was on the sidewalk, on the solid side of a bridge, but only 2' from the span end. I saw a concrete truck coming down the road at a good 50mph, then across the bridge. When he hit the joint the rod base kicked right off the point and stopped about 0.3' away. I was standing nearby and watched the whole deal. I replumbed the rod over the point. Any error was lost in the noise. I got a real tight solution. About 15 minutes later I saw another concrete truck coming. I walked over and was ready to catch it. It vibrated some but did not move. I could feel the vibration in the abutment since I was standing right at the joint.

I have come back several times to find a rod tip 0.02' from the center of the point. Usually it is some stress relaxing in the whole setup either due to vibration or to differential heating fo the triped legs. I have yet to let it concern me. Set it right and move on.

I might be concerned if it fell over, and the data should tell me if it was kinematic and for how long.

Concrete trucks give the most severe impact to roads and bridges. There is a lot of weight on a very short wheelbase. In all probability more than 50% of the concrete trucks are at least 20% over their per axle weight limit. A concrete drum has much more volume than it's rated capacity to provide proper mixing room. With that extra room it is easy to want to overload them.

While I was a student at Lehigh University in the early 70's the Engineering Department got a PennDOT grant to do stress analysis on highway bridges. The entire bridge over the Lehigh River near Allentown was covered with stress gauges and all the wires came down to a portable mainframe computer. It occupied a good size trailer. They were not inclined to leave it unattended, so they paid students to be night watchman. They were still working out bugs, so it would crash at least once each night. It takes a while to reboot one of those babies.

On the day shift you could tell there was a concrete truck crossing and exactly where it was by watching the data spikes. The testing determined there were some design flaws that they corrected along with a major rebuild of the deck. They later did the same testing on a similar bridge near Pittsburgh.

Paul in PA

One of the neaby counties actually placed a number of county control points on bridges(overpasses).

I always thought setting points like this was bad practice for GPS or leveling.

AND don't forget . . .those expansion joints DO SERVE A PURPOSE.

A lot of new monuments are set on or very near bridges. Probably half of the monuments along the Garden State Parkway (see above) are on the cross over bridges. They have very clear sky. But because of where they are, you never really want to leave a GPS unattended. If it falls over due to traffic vibrations it will more likely than not get run over. That will give you more sorrow than coming back to find your receiver has gone to Atlantic City without you.

Paul in PA