Sponsoring Agency Name and Address
Texas Department of Transportation
Research and Technology Implementation Office
P.O. Box 5080
Austin, TX 78763-5080
Performing Organization Name and Address 10. Work Unit No. (TRAIS)
Center for Transportation Research
The University of Texas at Austin
3208 Red River, Suite 200
Austin, TX 78705-2650
Application of UIT to signal mast arms traffic intersections Abstract
The application of Ultrasonic Impact Treatment (UIT) to signal mast arms in the field is
described. UIT has been demonstrated in the laboratory to provide a simple means to improve
the fatigue performance of the fillet weld of connection of the mast arm tube to the end plate.
The procedures used in the field are detailed and the time required for a repair documented. A
fatigue test of a mast arm treated in the field is presented. The fatigue test indicated that the
UIT treatment improved the performance of the connection to the level of a connection with a
thicker end plate. UIT provides a cost effective means of increasing the service life of the mast
arms at intersections where galloping oscillations of the mast arms have been observed.
