Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 12
Workload; Situational Awareness; Distraction
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Procedure; Manuals; Human Factors; Chart Or Publication; Airport
Aircraft X was taxiing out of an FBO ramp and made a left turn to cross the active runway after being told to taxi across the non-active runway. I was looking at a strip while giving a clearance to a different aircraft on frequency while Aircraft X crossed runway 28 hold short lines. He was noticed by the local control trainee at the time and he asked me what he was doing. At the moment I told Aircraft X to stop! The aircraft stopped and unfortunately Aircraft Y was on takeoff roll [and] was forced to abort takeoff. This is a known hot spot on the airport and is depicted on the airport diagram in the AFD. This has been an ongoing problem for years at our airport and our local safety counsel has brought it up numerous times that there needs to be better signage and better markings on the pavement.
I was training on LC.  Aircraft Y called up for VFR departure and cleared him for takeoff from Runway 28.  As Aircraft Y was approaching Taxiway A4; on takeoff roll; I scanned and saw an aircraft crossing the hold short for Runway 28 at Taxiway A3 (Aircraft X). I said 'What is that guy doing' to GC and immediately told Aircraft Y to hold position and then to cancel takeoff clearance.  Aircraft Y was able to come to a stop before Taxiway A3 and Ground Control had stopped Aircraft X.  Both aircraft were taxied out to Runway 28 and took off with no further incident or assistance needed.Recommendation: The intersection of Taxiway A3 and Runway 28 is a known hotspot.  This is a frequent occurrence that a pilot will get confused and think they're about to cross Runway 31 on Taxiway A. Something should be done to address this intersection to help the confusion.  Better signage and more clearly marked pavement is recommended.
AGC Tower controllers and pilot reported an aircraft entered an active runway at the same time as another aircraft was beginning its takeoff roll.