The Road System

[Tier-Group 3, 10th Floor, Reception Room]

Next, in the south-side reception room on Tier-Group 3's tenth floor, Marie consulted Dr. Hamada, the civil-engineering specialist, about roads. The wavy short hair tucked under her helmet was a dark brown that, depending on how the light caught it, took on a bluish-purple through structural color, with a bright blue-purple hair ornament. Large eyes. Of ordinary height, a little shorter than Marie, with somewhat swarthy skin and a relatively sturdy build. To look at her, she was exactly the kind of auntie a mountain god might take a shine to, but of course beach vitex has no male or female.

"Dungeon structures can only exist within the dungeon's sphere of influence. Because of this, at present the Iruma Magistracy's Kasumigaseki road and the Toshima Magistracy's Hiratsuka road both break off on the far side of the bridge. Couldn't we build a paved road from the bridge to the towns?"

"The material is the problem. Asphalt requires mining its raw heavy oil or synthesizing it with microbes, and concrete needs the high heat of a nuclear reactor to manufacture the cement. Some kinds of geopolymer-based material, though, we could probably prepare even in this dungeon. The only real hitch would be the volcanic ash."

"Then please proceed along those lines. Concrete paving has the weakness that it isn't suited to burying water mains, electrical cables, and the like (partial repairs are a nuisance), but in this world there's no need to worry about that. In the meantime, I'll send Scarlet west to Iruma and Kinran southeast to Toshima to push the discussions along."

[Tier-Group 3, 10th Floor, Reception Room]

Marie went on to confer with Dr. Ebara, the electrical specialist. Dr. Ebara was of unknown sex and unknown age. And, for good measure, of unknown identity.

"I'd summon the library's official vehicles, and since there are no artificial satellites, I'd set up a communications antenna in the dungeon's upper reaches. Within the sphere of influence we'd run elevated roads on autonomous driving; outside the sphere and in emergencies, remote control."

"You mean to make electric self-driving cars the backbone of transport, then. True enough, railways can't even be obtained, and for automobiles, gasoline is impossible to obtain. Under present conditions it's a sound choice, but its sustainability is in question."

"Will the 100-meter roads be unable to handle the traffic volume?"

"If the population grows there's that danger too, but first there's the matter of dungeon energy. If we summon a car for every resident and charge them all every day, the energy balance goes into the red, and in the worst case there's a danger the dungeon collapses."

"That would be a problem."

"Society itself is fundamentally on an Edo-period level, and even if we run buses alongside, we'll have no choice but to go basically on foot. There's no help for it."

"For the time being, let's say that passenger cars and vans are used by the Shiso (Asura), the retainers, and couriers and the like. Even if we introduce some buses, transport will remain a long-term problem."

[Tier-Group 3, 10th Floor, Reception Room]

Last of all, Marie conferred with Dr. Sakku, the mechanical-engineering specialist. To look at him, he was a slender man, a touch on the small side. Short, wavy black hair.

"Sawasdee khrap. So, recondition the bookmobiles into buses, is it?"

"That's right. Spreading passenger cars around runs into the dungeon-energy constraint, and railways can't even be obtained in the first place. Since this dungeon can only summon library equipment, we'll convert the self-driving-capable bookmobiles into buses."

"Ones modified so the sides open up would be hard to recondition, but if the body itself hasn't been altered much, converting them to buses is perfectly feasible. The trouble is that there are a lot of small minibuses, only a few mid-size buses, and hardly any large buses, by the look of it."

"First, let's run two services a day to each of the five directions. The farthest, the Hiratsuka direction, is about 200 km, so it's a three-hour one-way trip; since the battery runs dry in one direction, we'll need four vehicles to allow for charging time. Kasumigaseki and the others are only 40 to 80 km one way, so one vehicle each. Counting spares, please ready about ten."

This world's timekeeping is by temporal hours, but in the dungeon, for clarity's sake, the otherworld's clock is often used as well. However, since one day here is a little longer than in the otherworld, the time has to be reset every day.

Because a bookmobile's running distance is short, an electric bus doing 70 to 80 km/h with a cruising range of 100 to 200 km is plenty. For that reason it isn't suited to being summoned from the otherworld and put to highway-coach-style use.

Heavy vehicles such as long-distance coaches and trucks are mostly fueled by heavy oil (Grade A heavy oil), but hydrocarbon fuels like heavy oil, whether synthesized from algae or drawn from fossil fuel, can't be produced without large-scale factory facilities. That said, depending on the world, things may differ owing to technological circumstances or the tax system.