PHL GND CTLR DESCRIBED INCIDENT WHEN ARPT VEHICLE CROSSED RWY AT UNEXPECTED LOCATION; REQUIRING LCL CTLR TO CANCEL TKOF CLRNC.

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WHILE STAFFING THE GND CTL POS AT THE PHL ATC TWR; I ISSUED A CLRNC TO AN ARPT VEHICLE WHO WAS ESCORTING A TOWED ACFT TO 'PROCEED VIA TXWY Y AND CROSS THE 9L APCH.' THE VEHICLE SAID 'ROGER.' SHORTLY THEREAFTER; I OBSERVED THIS VEHICLE AND THE TOWED ACFT XING MIDWAY DOWN THE ACTIVE DEP RWY; RWY 27L AT TXWY Y. I IMMEDIATELY ALERTED THE LCL CTLR WHO THEN CANCELED THE TKOF CLRNC TO A DEPARTING REGIONAL JET WHICH HAD JUST STARTED ITS TKOF ROLL. THE ACFT QUICKLY AND SAFELY CAME TO A HALF AND TAXIED OFF THE RWY. THE PROB DEVELOPED WHEN I MISUNDERSTOOD THE DRIVER'S ORIGINAL (RECORDED) REQUEST WHICH WAS TO 'CROSS RWY 27L AT TXWY Y WITH TOWED ACFT.' I THOUGHT HE WANTED TO PROCEED ACROSS THE APCH END OF RWY 9L WHICH IS PARALLEL TO RWY 27L; BOTH BEING BISECTED BY THE SAME TXWY Y. THE PROB WAS COMPOUNDED WHEN THE DRIVER HEARD WHAT HE WANTED TO HEAR AND DIDN'T READ BACK THE XING INSTRUCTION VERBATIM. THIS WOULD HAVE GIVEN ME ANOTHER OPPORTUNITY TO CORRECT THE MISUNDERSTANDING. POSSIBLE SOLUTION: ACFT AND VEHICLES SHALL READ BACK ALL RWY XING CLRNCS VERBATIM.