Narrative:

It was early in the morning and we just had rain until approximately an hour earlier. Now the sun had just broken out of the clouds. I had asked the ground controller to drop the second row of shades. Which they replied 'they are already down'. It was unusually bright and glary due to the rain water reflecting off of the large open tarmac area on the southeast side of the terminal. I was handed three departures from ground control. All three were westbound. Two aircraft X type followed by a cargo. I thought I would coordinate a left turn for the first aircraft to help out approach control. I saw that a sweeper was abeam alpha 17 and told him to exit 11L. It's fairly common for him to not respond until he is actually clear of the runway. My main error was thinking he was doing this; that he was waiting to respond until he was actually clear of the runway; so this did not strike me as unusual. I scanned the runway and did not see the sweeper on the runway. I cleared aircraft X for takeoff. I watched aircraft X as he began his departure roll. Then I saw some movement at the departure end of the runway. I immediately grabbed the binoculars to get a better view. I saw that it was the sweeper. At this point aircraft X was near alpha 11; and I got on the radio and told the sweeper to exit the runway twice with no response. As aircraft X rotated at alpha 13 the vehicle was clearing at alpha 17; I then quickly tried to reach out to him twice but he had cleared the runway by the second transmission.height and location of the tower. Due to the low height of the tower cab and the distance to alpha 13; it's hard to see vehicles without weather. Today it was made worse by having a majority of overcast yet a large amount of brightness and glare from the water on the ground. I think the new tower that is being built will hopefully alleviate this issue as we've had many errors at that end of the runway in the last 10 years or so. Communication vehicles are issued to clear the runway; and very often the vehicles don't respond until they are actually clear the runway. They don't report 'roger' or 'exiting' 'wilco' etc.sometimes they will clear the runway and will not report off (which isn't a requirement.) due to this controllers have gotten in the habit of clearing people for takeoff without a response from the vehicle and just observing that they are clear of the runway. I think as a facility the vehicles should acknowledge the receipt of a transmission at all times. Radio dead spot we have reported many times about a dead spot at runway 21 near delta and at runway 29R at alpha 17. To my knowledge that has never been fixed. I'm not sure if that was a factor this time or not; but it has been a factor before with aircraft holding in position and not responding to the tower. Which was the same location as where the sweeper was when the incident occurred.

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Original NASA ASRS Text

Title: Two controllers and a pilot report of runway incursion due to a sweeper not exiting the runway and the Local Controller issuing a takeoff clearance.

Narrative: It was early in the morning and we just had rain until approximately an hour earlier. Now the sun had just broken out of the clouds. I had asked the ground controller to drop the second row of shades. Which they replied 'They are already down'. It was unusually bright and glary due to the rain water reflecting off of the large open tarmac area on the southeast side of the terminal. I was handed three departures from ground control. All three were westbound. Two Aircraft X type followed by a cargo. I thought I would coordinate a left turn for the first aircraft to help out approach control. I saw that a sweeper was abeam Alpha 17 and told him to exit 11L. It's fairly common for him to not respond until he is actually clear of the runway. My main error was thinking he was doing this; that he was waiting to respond until he was actually clear of the runway; so this did not strike me as unusual. I scanned the runway and did not see the sweeper on the runway. I cleared Aircraft X for takeoff. I watched Aircraft X as he began his departure roll. Then I saw some movement at the departure end of the runway. I immediately grabbed the binoculars to get a better view. I saw that it was the Sweeper. At this point Aircraft X was near Alpha 11; and I got on the radio and told the sweeper to exit the runway twice with no response. As Aircraft X rotated at Alpha 13 the vehicle was clearing at Alpha 17; I then quickly tried to reach out to him twice but he had cleared the runway by the second transmission.Height and location of the tower. Due to the low height of the tower cab and the distance to Alpha 13; it's hard to see vehicles without weather. Today it was made worse by having a majority of overcast yet a large amount of brightness and glare from the water on the ground. I think the new tower that is being built will hopefully alleviate this issue as we've had many errors at that end of the runway in the last 10 years or so. Communication Vehicles are issued to clear the runway; and very often the vehicles don't respond until they are actually clear the runway. They don't report 'Roger' or 'Exiting' 'Wilco' etc.Sometimes they will clear the runway and will not report off (which isn't a requirement.) due to this controllers have gotten in the habit of clearing people for takeoff without a response from the vehicle and just observing that they are clear of the runway. I think as a facility the vehicles should acknowledge the receipt of a transmission at all times. Radio Dead spot we have reported many times about a dead spot at Runway 21 near Delta and at Runway 29R at Alpha 17. To my knowledge that has never been fixed. I'm not sure if that was a factor this time or not; but it has been a factor before with aircraft holding in position and not responding to the tower. Which was the same location as where the sweeper was when the incident occurred.

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.