DULUTH, MN (KDAL) - Tuesday through Thursday this week, the U-S Coast Guard will be using a special truck to conduct an inspection of the Aerial Lift Bridge in Duluth.  Between 9 a-m and 3 p-m the bridge will remain in the down position except from noon to 1 p-m when it will open to allow waiting small masted vessels to pass.  The bridge will continue to open on signal for commercial vessels over 300 tons.  Motorists are also advised that there will be an obstructed lane on the bridge because of the inspection truck and traffic control signals will be in use from 9 a-m to 3 p-m Tuesday through Thursday.