When he reached the cab, Clay was already in the right-hand control seat and was running down the instrument panel check. The sergeant lifted the hatch door between the two control seats and punched on a light to illuminate the stark compartment at the lower front end of the car. A steel grill with a dogged handle on the upper side covered the opening under the hatch cover. Two swing-down bunks were racked up against the walls on either side and the front hull door was without an inside handle. This was the patrol car brig, used for bringing in unwilling violators or other violent or criminal subjects who might crop up in the course of a patrol tour. Satisfied with the appearance of the brig, Ben closed the hatch cover and slid into his own control seat on the left of the cab. Both control seats were molded and plastiformed padded to the contours of the troopers and the armrests on both were studded with buttons and a series of small, finger-operated, knobs. All drive, communication and fire fighting controls for the massive vehicle were centered in the knobs and buttons on the seat arms, while acceleration and braking controls were duplicated in two footrest pedals beneath their feet. Ben settled into his seat and glanced down to make sure his work-helmet was racked beside him. He reached over and flipped a bank of switches on the instrument panel. "All communications to 'on,'" he said. Clay made a checkmark on his list. "All pre-engine start check complete," Clay replied. "In that case," the senior trooper said, "let's give Beulah some exercise. Start engines." Clay's fingers danced across the array of buttons on his seat arms and flicked lightly at the throttle knobs. From deep within the engine compartment came the muted, shrill whine of the starter engines, followed a split-second later by the full-throated roar of the jets as they caught fire. Clay eased the throttles back and the engine noise softened to a muffled roar. Martin fingered a press-panel on the right arm of his seat. "Car 56 to Philly Control," Ben called. The speakers mounted around the cab came to life. "Go ahead Five Six." "Five Six fired up and ready to roll," Martin said. "Affirmative Five Six," came the reply, "You're clear to roll. Philly Check estimates white density 300; green, 840; blue 400; yellow, 75." Both troopers made mental note of the traffic densities in their first one-hundred-mile patrol segment; an estimated three hundred vehicles for each ten miles of thruway in the white or fifty to one hundred miles an hour low lane; eight hundred forty vehicles in the one hundred to one hundred fifty miles an hour green, and so on. More than sixteen thousand westbound vehicles on the thruway in the first one hundred miles; nearly five thousand of them traveling at speeds between one hundred fifty and three hundred miles an hour. Over the always-hot intercom throughout the big car Ben called out. "All set, Kelly?"