"Not hard at all. Especially here. The service roads are easy to follow. We've learned the code for the signs on the walls that service machines used—not that different from bar codes on Earth. Replaces street signs. I just shine a pen reader on the signs near the corners and we know where we are. I tell you when to turn. . . you turn. All the service roads are surrounded by walls; you can't fall off anything even if you try. Okay?"

"Okay."

He climbed into the shotgun seat and showed her the column guidance system. "It's like an airplane in one respect—push the column forward and the truck moves forward; the farther you push, the faster it goes, up to a hundred klicks. Slow down by pulling the stick back to upright; reverse by pulling the stick toward you. Maximum speed in reverse is about ten klicks. Gear shifting is automatic. Grip the handles on the horizontal bar and twist the bar the direction you want to go. If you want to make a complete about-face without moving forward or back, just hold the column on the center line and twist the bar as far as it will go. The truck will rotate around its center line. Want to practice?"

"Of course." She maneuvered the truck back and forth around the garage. Using the stick as a brake took some getting used to. When she felt she was reasonably proficient, she smiled at Takahashi. "Let's go," she said.

"Catch on fast, don't you?"

"Don't speak too soon," she warned.

"Okay. Spin us around." He pointed out the nearest service entrance.

The walled service roads wound through and under the city's buildings, usually avoiding grades steeper than ten or fifteen degrees. In one section, however, the ride resembled a roller coaster. Takahashi coaxed her up and down the slopes. "We just passed over the main plumbing for this neighborhood," he explained.

Where the service roads became tunnels, and where the arches and other structures blocked out most of the tubelight, large milky panels cast a soft illumination. The city was without appreciable shadow; everything was cast in a rich and even light.

Takahashi suggested she slow down as they approached a branch in the serviceway. He took a pen reader from his pocket and pointed it at a squiggle of lines of uneven thicknesses near the end of the left-hand wall. The pen was hooked to his slate, which displayed a map, a digital coordinate and directions to nearby points. "Left," he said. "We'll be entering the apartment building soon. By the back door, so to speak."

The serviceway soon passed beneath the plaza of a dazzling gold-surfaced cylindrical tower. Lights flashed at them as they passed, but the shape of the truck—or their presence within—did not trigger any automatic responses.

"Stop at that open door ahead," Takahashi said.