This trap is on the Cambridge to Charlestown side of the bridge. As you enter the bridge after going under the Green line T tracks, you will see your first "Speed Limit 30" sign. As you continue on the span, the roadway rises and you will see another "Speed Limit 30" sign about midway across the bridge. A patrol car will usually be located just over the crest on the right shoulder and about 100 feet after the 2nd speed limit sign. The state trooper will either use a K-band radar, Ka band radar, or laser gun. Those that get pulled over will be waved over to the side of the road where a ticket will be issued. This trap can be see during non-rush hour times. This is a well concealed spot since you will not see the patrol car until it is too late.