Another close call, apparently due to a mis-hearing and an uncorrected readback.
Aviation Herald:
A Southwest Airlines Boeing 737-700, registration N212WN performing flight WN-471 from Baltimore,MD to Chicago O'Hare,IL (USA), was cleared for takeoff from Baltimore's runway 15R and commenced takeoff at 13:58L (18:58Z).
A fire and rescue vehicle (ambulance) was cleared to cross runway 10 and hold short of runway 15R at the ARFF road (about 5700 feet/1740 meters down runway 15R), the vehicle however read back to cross runway 10 and 15R. The controller did not correct that read back. The vehicle continued and crossed runway 15R while the Boeing 737 was in their takeoff run.
The Boeing 737 continued their takeoff, became airborne and continued to destination without further incident.
The FAA reported in their safety summit held as result of other losses of runway separation listing a total of 8 such occurrences, that the aircraft became airborne just before the intersection where the vehicle was crossing. The distance between aircraft and vehicle had reduced to about estimated 173 feet horizontally, by the time the aircraft went past the intersection the vehicle was already about 170 feet past the runway. The FAA rated the runway incursion as Category B (significant potential for collision).