Local controller reported forgetting about vehicles on a runway when the arrival aircraft alerted co...

Narrative:

I took over the local control (local control) position. Airport operations (ops) X plus 1 had just been put on the runway to repair lights. The rid [runway incursion device] was activated. A few minutes later ops moved farther down the runway and asked when the next arrival was. I looked at my strips and told him 20 plus minutes. He said that was plenty of time for him to finish up. I'm estimating maybe 10 minutes later; I noticed aircraft X on a wide left downwind for ZZZ. I realized I did not have his strip for some reason and started looking for it in the recycle bin. I found it; and a few moments later aircraft X checked on and I cleared him to land; I had completely forgotten about ops on the runway.on about a 2.5 mile final; aircraft X said he saw someone on the runway. I sent him around and ops said they were exiting. I switched the aircraft X to the crossing runway and he landed safely. I checked the rid and saw the volume was turned all the way down; I should have noticed that the first time I talked to ops. I'm sure I scanned the runway but at this point; I don't know how I could have missed the vehicles. The sun was going down and the shades were still pulled down; we also have very large posts that can obstruct our view and we need to move to see around them sometimes. I'm not sure if any of that was a factor or not in forgetting about them. I do remember thinking that the ops should be no factor for anyone when I thought the next arrival was proposed for more than 20 minutes out; I must have let my guard down. I usually write out a strip or a reminder of vehicles and put it in front of me or on top of my proposal strips but today for some reason I did not do that. This situation was completely my fault and I can't think of any recommendations for the position; just for myself. Even though there is no specific volume requirement; I plan on checking the rid and turning it up very loud when I activate it from now on. I do think it is a very useful tool; I use it often; and I have never forgotten about a vehicle before. I need to continue working on and improving my scan; write out a strip or a reminder of the ops vehicle. I also think I will ask the ops to advise when they are moving from light to light. If I had done that; I would have talked to the ops vehicle a few more times and maybe would not have forgotten about them.

Original NASA ASRS Text

Title: Local Controller reported forgetting about vehicles on a runway when the arrival aircraft alerted Controller to the fact there were vehicles on the runway.

Narrative: I took over the Local Control (LC) position. Airport Operations (Ops) X plus 1 had just been put on the runway to repair lights. The RID [Runway Incursion Device] was activated. A few minutes later Ops moved farther down the runway and asked when the next arrival was. I looked at my strips and told him 20 plus minutes. He said that was plenty of time for him to finish up. I'm estimating maybe 10 minutes later; I noticed Aircraft X on a wide left downwind for ZZZ. I realized I did not have his strip for some reason and started looking for it in the recycle bin. I found it; and a few moments later Aircraft X checked on and I cleared him to land; I had completely forgotten about Ops on the runway.On about a 2.5 mile final; Aircraft X said he saw someone on the runway. I sent him around and Ops said they were exiting. I switched the Aircraft X to the crossing runway and he landed safely. I checked the RID and saw the volume was turned all the way down; I should have noticed that the first time I talked to Ops. I'm sure I scanned the runway but at this point; I don't know how I could have missed the vehicles. The sun was going down and the shades were still pulled down; we also have very large posts that can obstruct our view and we need to move to see around them sometimes. I'm not sure if any of that was a factor or not in forgetting about them. I do remember thinking that the Ops should be no factor for anyone when I thought the next arrival was proposed for more than 20 minutes out; I must have let my guard down. I usually write out a strip or a reminder of vehicles and put it in front of me or on top of my proposal strips but today for some reason I did not do that. This situation was completely my fault and I can't think of any recommendations for the position; just for myself. Even though there is no specific volume requirement; I plan on checking the RID and turning it up very loud when I activate it from now on. I do think it is a very useful tool; I use it often; and I have never forgotten about a vehicle before. I need to continue working on and improving my scan; write out a strip or a reminder of the Ops vehicle. I also think I will ask the Ops to advise when they are moving from light to light. If I had done that; I would have talked to the Ops vehicle a few more times and maybe would not have forgotten about them.

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	1626295
Time
Date	201903
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Tower
State Reference	US
Aircraft 1
Flight Phase	Final Approach
Route In Use	None Visual Approach
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 7.5
Events
Anomaly	ATC Issue All Types Conflict Ground Conflict Less Severe Deviation - Procedural Published Material / Policy

Local controller reported forgetting about vehicles on a runway when the arrival aircraft alerted controller to the fact there were vehicles on the runway.