Tus ground and local controller reported a runway incursion due to ground control conducting other f...

Narrative:

I had just taken possession of ground control with flight data/clearance delivery combined because the FD/clearance delivery controller was on his way home sick. A rescue vehicle called to relocate from the base of the tower over to the west end of the airport. Initially; I told the vehicle to hold short of the crossing runway (runway 21) as I was busy helping to sign out the controller going home. Runway 21 being active had already been coordinated with me for an inbound landing. After working on the computer I turned to notice the vehicles approaching runway 21 at taxiway alpha and forgot why I was holding them there; and told them to cross the runway. I saw that we had an aircraft on final and instructed local to send them around while the vehicles were crossing. He did so and the aircraft circled for runway 21 and landed safely.I should have been more aware that I stopped that aircraft for a reason. Had I moved back to my working position at ground; I would have seen why and used the placards and info written down in front of me as a reminder to leave them where they were (already holding short of the runway for an inbound).the shift was very short-staffed and I was being used for staffing and relief to support the operation. I was not anticipating losing another body to sick leave on an already short shift.

Original NASA ASRS Text

Title: TUS Ground and Local Controller reported a runway incursion due to Ground Control conducting other functions as the FLM. Ground Control crossed vehicles with aircraft on short final due to being distracted.

Narrative: I had just taken possession of Ground Control with flight data/clearance delivery combined because the FD/CD Controller was on his way home sick. A rescue vehicle called to relocate from the base of the tower over to the west end of the airport. Initially; I told the vehicle to hold short of the crossing runway (Runway 21) as I was busy helping to sign out the controller going home. Runway 21 being active had already been coordinated with me for an inbound landing. After working on the computer I turned to notice the vehicles approaching Runway 21 at Taxiway alpha and forgot why I was holding them there; and told them to cross the runway. I saw that we had an aircraft on final and instructed local to send them around while the vehicles were crossing. He did so and the aircraft circled for Runway 21 and landed safely.I should have been more aware that I stopped that aircraft for a reason. Had I moved back to my working position at ground; I would have seen why and used the placards and info written down in front of me as a reminder to leave them where they were (already holding short of the runway for an inbound).The shift was very short-staffed and I was being used for staffing and relief to support the operation. I was not anticipating losing another body to sick leave on an already short shift.

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.

Attributes
ACN	1367082
Time
Date	201606
Local Time Of Day	1201-1800
Place
Locale Reference	TUS.Tower
State Reference	AZ
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	VFR
Person 1
Function	Supervisor / CIC Ground
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 5
Person 2
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 Less Severe Deviation - Procedural Clearance Ground Incursion Runway

Tus ground and local controller reported a runway incursion due to ground control conducting other functions as the flm. Ground control crossed vehicles with aircraft on short final due to being distracted.