During time trials, a new safety rule was put into place to convey to the officials the start of a qualifying attempt. When a driver was on his three warm-up laps, a crew member(s) from his team was now stationed at the north end of the mainstretch, and provided with two flags (green and yellow). When the car came around after the third and final warm-up lap, the crew member was instructed to wave a green flag in the air to signify the driver will begin the run. If the crew waves a yellow flag, or waves no flag, the run does not start, the car returns to the pits, and the attempt does not count. As in previous years, each car was still permitted up to three official qualifying attempts.