I'm not an expert, but I would think creating or changing existing routes for trolleybuses would require setting up overhead wires, which probably need a few things to be in place beforehand. Isn't that just slower/costlier than simply driving on a different street? What about intercity routes? Doesn't sound superior to me on that front.

edit: grammar

Changing routes isn't really that frequent once you have a working setup.

As for intercity travel, this should be set up as rail, not a bus, in basically 100% of cases.

I've been to major European cities in the last few weeks, Paris, London, Edinburgh, all of them, with no exception had bus routes changed temporarily because of construction, protests, events etc. Of course it's frequent.

Most trolleybuses I know have independent emergency propulsion and can reattach without too much difficulty at specific places (usually stops). So temporary short rerouting isn't difficult. Apparently they even have trolley/battery hybrids in zurich where the battery is used as part of normal operation (claiming to need wires only for ~half of the route).

I can't see it as being superior in every way. In most cities where I've spent significant time with the public transit system, it's relatively common for the buses to need to reroute around things like road construction and street festivals. Also, buses frequently need to pass other buses on the same route that are stopped due to equipment problems or running slowly due to overcrowding. A trolleybus would have a hard time dealing with those sorts of things.

It's also, I would guess, a lot more difficult to get off the ground. With battery powered buses, you just buy however many buses, and throw them on whatever pre-existing route. With a trolleybus, you need to install the overhead wire system before you can get started.

And then, I would imagine the overhead wire system itself becomes a problem. Do you have to worry about transporting oversize loads on or across the same streets? Is it going to become another electrocution hazard for people who need to work above the street? etc.

That's not to say there aren't advantages to trolleybuses, too. Just that the claim that it's "in every way superior to batteries" is an overreach.

The buses I've seen are still capable of going under their own power, and they can easily attach/detach from the wires: https://www.youtube.com/watch?v=9k1z10U3utc

So detours and overtakings are no big deals.

What about an hybrid solution? Smaller batteries could let trolleybuses venture from their infrastructure as needed, but at a reduced cost.

We had this here in the Netherlands, the system broke down quite a lot and apparently had quite some wear and tear

I guess it can be improved thoug.

How do they re-attach the bus to the power lines? Is it reasonably automatic, or does the driver have to fuss with it?

It's not an overreach, trolleybuses work surprisingly well at the moment. Lighter, much, much cheaper, less electricity required. And you need less of them.

Metro, trams, trolleybuses should be used primarily and then you can add electric buses for gaps. That would make sense, not trying to go straight for the most expensive and wasteful option.

How can they be cheaper? You still need to install all the overhead wiresm this only works if you assume they the routes never change. And will require an absurdly huge initial investment. Might be better/cheaper to just see if batteries get better or if more quick charge points can he installed.

The vehicules are have less components thus are both cheaper upfront and cheaper on at operation by being lighter and requiring less maintainance. Because of that they are on average bigger so you can have a smaller fleet. Also installing overhead cables isn't such a big investment (in the face of related urban investment needed anyway like road maintainance, street furnitures and traffic/lanes shaping). Remember that tons of cities install christmas decorations with similar overhead wires just for one month every year.

I wonder how many more passengers a trolley bus can carry, compared to a battery powered bus of the same size

Don't trolleybuses require overhead wires? Doesn't that mean you would need to retrofit all routes with poles, cables, etc? How do they cope with diversions?

No. I live in a city with wires but many buses go from the city into the surrounding areas. And to put up wires threw all the lower density areas where people live is just a bad idea.

Modern batteries can go for decades.

A battery based system is far more flexible, you can uses buses all over the place and dynamically adjust routes based on demand.

Overhead wires are also significantly ugly to have in a city.

This. It's astonishing that someone would put batteries into these things.

Superior in every way except for massive infrastructure costs, unsightly wires or rails, and fixed routes, I suppose.

Trolleybus routes require additional costs for maintenance. This might be significant

Otoh vehicule maintenance, cost and energy use is smaller.