Narrative:

Plan X; departing runway 04L/09R/32R and landing runway 09; [and I was] working north local control. Aircraft X was taxied to runway 32R intersection V for departure. He was filed over eon which is a south bound fix. If I had departed him off of runway 32R/V he would have stopped all my departures temporarily to get him turned southeast bound. I felt it would be easier to back taxi him to runway 14L at U2 so I could depart him on a runway heading and he would not tie up any of my airspace. I instructed aircraft X to taxi on runway 32R and hold short of 04L as I had air carrier Y in position. Once my runway 09R arrival had landed; I rolled air carrier Y off runway 04L. During this time I was crossing runway 09R with a heavy B767; loading runway 09R with a departure; and ensuring the 09R lander was clearing the runway because I needed to get the 09R departure rolling soon because the next runway 09R arrival was near the outer marker. Right as air carrier Y was going through the intersection of runway 09R; I was getting ready to roll my next runway 09R departure when my local assist instructed me to stop aircraft X. Right when I began to key in to stop aircraft X; the asde-X alerted and I instructed the traffic to stop. Air carrier Y didn't seem to hesitate at all and continued with the take-off roll. Air carrier Y departed without incident. Aircraft X appeared to be clear of the runway and air carrier Y never said anything when I shipped him over to departure. I then instructed aircraft X to cross runway 04L and had him exit the runway. Upon review of the asde-X data and a phone call from the pilots; aircraft X was about 150 ft from the runway 04L intersection. The speed of the taxi is what probably set off the asde-X and the pilots said they were going to get confirmation from me prior to crossing runway 04L.

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Original NASA ASRS Text

Title: ORD Controller described a ground conflict when traffic; cleared via a runway; activated an ASDE-X alert approaching an active runway with a departure rolling; taxi speed was listed as a possible alert activation factor.

Narrative: Plan X; departing Runway 04L/09R/32R and Landing Runway 09; [and I was] working North Local Control. Aircraft X was taxied to Runway 32R Intersection V for departure. He was filed over EON which is a south bound fix. If I had departed him off of Runway 32R/V he would have stopped all my departures temporarily to get him turned southeast bound. I felt it would be easier to back taxi him to Runway 14L at U2 so I could depart him on a runway heading and he would not tie up any of my airspace. I instructed Aircraft X to taxi on Runway 32R and hold short of 04L as I had Air Carrier Y in position. Once my Runway 09R arrival had landed; I rolled Air Carrier Y off Runway 04L. During this time I was crossing Runway 09R with a heavy B767; loading Runway 09R with a departure; and ensuring the 09R lander was clearing the runway because I needed to get the 09R departure rolling soon because the next Runway 09R arrival was near the outer marker. Right as Air Carrier Y was going through the intersection of Runway 09R; I was getting ready to roll my next Runway 09R departure when my Local Assist instructed me to stop Aircraft X. Right when I began to key in to stop Aircraft X; the ASDE-X alerted and I instructed the traffic to stop. Air Carrier Y didn't seem to hesitate at all and continued with the take-off roll. Air Carrier Y departed without incident. Aircraft X appeared to be clear of the runway and Air Carrier Y never said anything when I shipped him over to departure. I then instructed Aircraft X to cross Runway 04L and had him exit the runway. Upon review of the ASDE-X data and a phone call from the pilots; Aircraft X was about 150 FT from the Runway 04L intersection. The speed of the taxi is what probably set off the ASDE-X and the pilots said they were going to get confirmation from me prior to crossing Runway 04L.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.