Is it common to have subway lines in Munich and Berlin accessible by escalator , or all steps? Elevators?
Like in the US ...Yes and No. Both Berlin and Munich have both S-Bahns and U-Bahns. Both systems in each city have stairs and elevators and escalators, if they are working.... Check out accessible travel for the systems for where you want to go; And, of course, when you want to travel since maintenance is an ongoing effort.
Examples:
https://sbahn.berlin/en/plan-a-journey/rail-stations/accessible-travel/
https://themunicheye.com/new-escalators-for-the-u-bahn-network-621
Just seconding what Nick said. It varies by station. If you absolutely need elevators or escalators, you will have to check the particular stations you are using.
The linked lists give an incomplete and not official view, because in both cities S-Bahn and rest of transport are operated by different companies - even same tariff and t&c.
In both cities you can assume to find 70-80% of stations barrier-free, minmum at one entrance. Ratio is higher in center areas. Stations at outer districts can also have wide ramps to avoid stairs.
Be aware: In both cities you can find also faulty lifts as well as escalators under repair.
Munich: On MVV website you will find the maps for wheelchair passengers which means lift available.
Berlin:
- S-Bahn accessible travel website (provided before): some stations offer wide ramps to avoid stairs.
- BVG operates U-Bahn, trams and buses: Last page of BVG barrier-free brochure contains a complete map of network with accessibility information. See also BVG webpage with faulty lifts.
- BrokenLifts is a project supported by both companies and gives an overview of lifts under repair for whole Berlin public transport network.
Also very important in both cities: never forget to validate / time stamp physical tickets.
More infos and tips on Berlin public transport.
Last tip: really a lot of good information and useful links are provided on VisitBerlin webpage for for wheelchair users and visitors with limited mobility.
Have a safe and good journey.
Most German cities are working very hard to get all train stations, subway stations, and tram stations accessible, and many of them are doing pretty well in that respect by now.
However, that's not going to do you any good if you happen to end up having your hotel near a station that is currently under construction, so I can only agree with what the others said: Check out the current state of those stations that you will likely be using.