Elizabeth line testing ways of banishing its "ghosts in the walls"

There is improve and there is trying something new. Rails have been around for nearly two centuries - they are a solve problem. We don't need to innovate on many parts as there is nothing wrong with the old technology with some minor updated. We already know what works well for a standard train system. Innovation generally tries things that look good to politicians who don't understand trains, but in reality people who understood trains 100 years ago had the idea and rejected it as a bad idea - and the reasons they are bad ideas didn't change!

there is a lot of room to improve trains. However it all starts with standard gauge steel track, with standard sizes tunnels, standard switches, standard control algorithms (with computers this had recently had a revolution, while there is room to improve this is again in the mostly solve area), standard "rolling stock" and so on. Let me bring out here two standards that are a bit new: platform doors - now that someone invested them and proved they work everyone should retrofit to them; and elevators - it is criminal that many stations around the world still haven't been retrofitted (criminal as in I think someone should be in prison anywhere you find they have not been retrofitted) Once you have all the standard stuff laid out you can make a few tweaks to see what works, but only a few as we know the standard stuff works.

Make sure when you look at standards above you look at what others have done. If you have an idea odds are someone else has already tried it: find them and figure out how it works - sometimes you can tweak to be better sometimes you realize it is a bad idea.

All buildings - including stations should have maintenance schedules. There are things to do hourly (or when open), every 2 hours, 4 hours, daily, weekly, monthly, and yearly. In addition you have 5, 10, and 30 year remodel cycles.

Of course you always have someone do urgent maintenance - if a pipe breaks you fix it now. However replacing that pipe might leave a poorly patched wall until the next 10 year cycle when the fix is made invisible.

You have to empty trash, clean the floors, and other similar things several times per day.

Every year you replace filters and do a deep cleaning. (check the documentation for equipment - sometimes this might be a 1 month cycle not 1 year!) You also do a full inspection of everything, touch up paint, and patch anything else. This should be very routine, and thus always cost the same (inflation adjusted).

Every 5 years you repaint. You also replace carpet where overly stained. That is touch up the cosmetics in a more in depth way. However this is a small cost.

Every 10 years you have to do significant work in the bathrooms (While toilets can last for centuries they start to look bad when you try in a commercial setting). If there is a kitchen it also needs significant work. Avoid moving major things, but this is a higher cost. You should probably be replacing benches on this schedule.

Every 30 years you do a major remodel. Here is where you update everything at sometimes high cost. Add elevators if you don't have them. Expand the station footprint if it is too small (you need more stains). Move where the doors are. Change the station approaches. Add more bathrooms. This will be expensive.

Probably a lot less than it costs to build, ship, and actively power the displays.

It's easy to estimate: if the displays + lifetime power costs more than all the posters, then chances are they use a lot more power. The cost of electricity isn't one of those externalities a business can hoist on society - it has to pay for each kilowatt-hour and that cost is easily quantifiable.

Wild rats aren't naughty. They're just animals trying to make their way in the world the same as the rest of us. But they do make a mess and carry diseases, again maybe the same as the rest of us lol.

Sometimes - but some large buildings have loads of space above suspended ceilings and in cable trays and suchlike. Office buildings know every new tenant might want to move internal walls, rearrange sockets, reconfigure the kitchen and so on, and they're built with that in mind.

You're right that making arbitrary ad-hoc changes during construction can be expensive, of course. Especially if it's wrong and has to be torn out and redone.

But it's not illegal - if you're in charge of a project and an installer tells you the specified vents are going to be a problem and they recommend a bigger one, nothing in law prevents you from telling them to go ahead and make the change, right there on the spot.

Of course, how often the person with in charge of a large project will be talking to the vent installers while they're working is a different matter...