sentences:  91 Express Lanes customers pay tolls from pre-paid accounts, using a FasTrak transponder — a pocket-sized radio transmission device mounted to the inside of their vehicle's windshield.This electronic toll collection technology eliminates the need to stop and pay tolls at traditional tollbooths, thus ensuring the free flow of traffic on the 91 Express Lanes.The 91 Express Lanes was born from the need for congestion relief on the 91 Freeway when no public funds were available to solve this critical transportation problem.