How to build an underground city
1. Don't use Nixie tubes for the countdown timer, they're so 1970s.
2. Provide the instructions for egress in a safe built into the mayor's office, don't put them in a box that can easily be mislaid. The second key attached to the mayor's chain is all that needs to be handed over.
3. Don't print the instructions on edible paper.
4. Don't use easily sunk little boats.
5. Don't put a waterwheel in the way.
Also, I don't know about the book, but why is most of the technology from the first half of the 20th century? The filament lights, the levers and dials &c.?
I think it would have been better if the technology had been very futuristic, but failing. Electroluminescent panels in the ceilings, most of them faulty, and replaced by oil lamps and crude arc lamps plugged into the mains sockets.
And the food cans looked like regular ones, not some kind of super-duper vacuum packed irradiated synthetic food that might feasibly last for hundreds of years.
I liked the way they had to plug their headlamps into the mains with long cables. Rechargeable batteries fail eventually.
I liked the way that jobs were allocated by lot, but weren't some of the graduates just children? How would they do the job of a pipeworks labourer? (For that matter Saoirse Ronan wouldn't have taken to her allocated job very well.) It seemed to be rather easy to swap roles, but maybe that was more or less intended.