Sea local controller reported observing a taxiing aircraft cross the hold short lines of a runway as...

Attributes
ACN	1408292
Time
Date	201612
Local Time Of Day	0601-1200
Place
Locale Reference	SEA.Tower
State Reference	WA
Environment
Light	Daylight
Aircraft 1
Make Model Name	Medium Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Route In Use	None
Flight Plan	IFR
Aircraft 2
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Route In Use	None
Flight Plan	IFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 1
Events
Anomaly	ATC Issue All Types Conflict Ground Conflict Critical Deviation - Procedural Published Material / Policy Ground Incursion Runway

Narrative:

I put aircraft Y into position to hold on runway 34R while I crossed aircraft downfield. I crossed the two aircraft that were holding short of that runway. I then went to aircraft X who was holding short of runway 34C at taxiway J and had him cross 34C and hold short of 34R. Once the first two aircraft were across runway 34R I scanned the runway and cleared aircraft Y for takeoff. As he was starting his roll I noticed aircraft X moving at a good speed and crossing the hold short lines for runway 34R. As soon as a saw this I told him to stop and he immediately slammed on his breaks. I then went to aircraft Y and cancelled his takeoff clearance. Aircraft X was given the brasher warning by ground control and when he called the tower he said that the sun was in their eyes and they were unable to see the hold lines.I feel that the position of taxiway J/H as it crosses 34R is an issue. This intersection was just redone and the new layout is a hazard. When we use this taxiway for staging; which is only in a north flow; the aircraft holding there are facing to the northeast; away from traffic at the approach end of runway 34R. It was only a matter of time before something like this happened at this new hot spot.

Original NASA ASRS Text

Title: SEA Local Controller reported observing a taxiing aircraft cross the hold short lines of a runway as a departure was beginning its takeoff roll.

Narrative: I put Aircraft Y into position to hold on Runway 34R while I crossed aircraft downfield. I crossed the two aircraft that were holding short of that runway. I then went to Aircraft X who was holding short of Runway 34C at Taxiway J and had him cross 34C and hold short of 34R. Once the first two aircraft were across Runway 34R I scanned the runway and cleared Aircraft Y for takeoff. As he was starting his roll I noticed Aircraft X moving at a good speed and crossing the hold short lines for Runway 34R. As soon as a saw this I told him to stop and he immediately slammed on his breaks. I then went to Aircraft Y and cancelled his takeoff clearance. Aircraft X was given the brasher warning by ground control and when he called the tower he said that the sun was in their eyes and they were unable to see the hold lines.I feel that the position of Taxiway J/H as it crosses 34R is an issue. This intersection was just redone and the new layout is a hazard. When we use this taxiway for staging; which is only in a north flow; the aircraft holding there are facing to the northeast; away from traffic at the approach end of Runway 34R. It was only a matter of time before something like this happened at this new hot spot.

Data retrieved from NASA's ASRS site 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.

Sea local controller reported observing a taxiing aircraft cross the hold short lines of a runway as a departure was beginning its takeoff roll.