Barrier light sequence change effective July 1 Published May 13, 2013 By 11th Security Forces Squadron JOINT BASE ANDREWS, Md. -- Headquarters Air Force is implementing a new lighting procedure to follow when entering and exiting gate barriers slated to begin July 1, 2013. Currently, vehicles go on flashing yellow and stop on red. When the change begins, vehicles will proceed through the barriers when no lights are present and they will stop on flashing yellow. When you see the flashing yellow light it means the pop-up barrier has been activated. DO NOT PROCEED. Wait until there are no lights present before proceeding. If stopped at a light, DO NOT STOP ON THE BARRIER SYSTEM. These barriers deploy with enough force to lift your vehicle off the ground. Please be mindful of this change in procedure taking place in upcoming weeks. The active vehicle barrier system, or pop-up barrier, is designed to physically prevent unauthorized vehicles from entering Joint Base Andrews. The pop-up barriers are hydraulic, manually operated, systems that deploy in just over one second. As a safety feature, there are light systems immediately next to each barrier. Please contact the Anti-terrorism Office at 240-612-6313 with any questions or for additional information. We look forward to protecting you, while together we defend America. Thanks for your cooperation.