Wisconsin state troopers have been doing that for many years now. Some of them sit in the middle of the bridge, some are more clever and sit off all the way to either side, making them a bit harder to spot. A surefire way to know is you can usually see they have their window open, because they cannot shoot laser through glass. That applies to whether or not they are on a bridge or in the median. Since laser has become so inexpensive over the past 5 years now, they have switched to primarily using that instead of Ka radar. Ka is way to easy for a good detector to pick up, laser is next to impossible, and once you get hit its too late, its just alerting you to a ticket at that time! Laser jammers are legal in wisconsin still, so go ahead and get one installed for $800 if you want. The escort 9500ix with gps will allow you to mark those locations, which is what i do now, that way you can go on the defensive and not even worry about the laser threat. I would recommend marking the location with the 9500ix well ahead of where you know the location to be, because the detector does not give enough warning time if you are doing 80mph+, they can laser you at greater than a half mile and get a reading no problem if conditions are good.
Lots of people even with good detectors(V1 or 9500ix) wont even know they have been lasered by a good operator because the beam dispersion is so small its likely not to even hit the sensor on the detector! Hats off to the technology in laser speed enforcement, its pretty damn good!
