Phantom jam
Phantom jam turns up in 2 fields: logistics, shop slang. Here is what it means to the people in each one.
Phantom jam in logistics
A traffic bottleneck that forms on a highway without any physical obstruction or crash.
A phantom jam is a localized wave of slow or stopped traffic caused by driver behavior rather than a collision, lane closure, or physical bottleneck. It typically starts when one driver brakes slightly, causing the following driver to brake harder, creating a backward-propagating shockwave of deceleration. These jams can persist for hours and travel upstream against the flow of traffic.
"The sensors show a phantom jam moving backward at about ten miles per hour near mile marker 42."
Phantom jam in shop slang
A false error message indicating a paper jam in a printer or copier.
A machine error where a printer, scanner, or copier halts operation and reports a paper jam, despite the paper path being completely clear. These faults are usually caused by dirty optical sensors, worn feed rollers, or tiny scraps of torn paper hiding deep inside the mechanism. They force workers to open and slam every access door repeatedly to clear the false flag.
"The copier on the second floor is throwing a phantom jam again, so just open tray two and shut it hard."