In this case there were two arrivals within 4 minutes of each other and two departures, in addition to the emergency plane that had just aborted takeoff.

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pc86 5 hours ago | parent [-]

Which is a completely reasonable amount of traffic for one controller to handle. This wasn't the controller's fault. The firetruck received a clearance, had that clearance revoked, and either didn't hear the revocation or ignored it.

	▲	bombcar 4 hours ago \| parent \| next [-]
		If you have ever spent time listening to LiveATC you will realize that like everyone, "tunnel ear" is a real thing - if United 1002 has received the clearance/instructions they expect, read them back, and are proceeding it can be moderately difficult to get their attention again, even with perfect verbiage.
	▲	mannykannot 3 hours ago \| parent \| prev [-]
		The controller was not guilty of malfeasance, but clearing the trucks onto the runway with an airliner on short final was a mistake, no matter whatever else one could say about it.