train sees locomotive as a wagon -> speed is lowered

when you build a train that's made out of:
locomotive
6 wagons

the train will keep it's max speed of 80km/h ,which is normal,and if you add one more wagon which makes it look like this:

locomotive
7 wagons

it's speed will decrease to 79km/h , which is also normal,HOWEVER if you then add one more locomotive to it and put it at the end of the train,which will make it look like this:

locomotive
7 wagons
locomotive

the second locomotive will act as ballast instead of adding more power to the whole train which will lower max speed to 72km/h instead of making it 80km/h again

if you switch the second locomotive with the last wagon and make it look like this:

locomotive
6 wagons
locomotive
1 wagon

the train will keep it's max speed of 80km/h which confirms it's a bug

I think the intention might have been to have double headed trains, as can be seen with the obviously reduced backwards speed with locomotives only at the front. This would in turn mean that locomotives would only use their full power in a single direction (which doesn't make too much sense IMO as we don't have railyards that can rotate only locomotives instead of the full train)

Adding a locomotive with this reasoning would indeed mean that it is dead weight when going forward. However there definitely is some algorithmic error that makes chaining locomotives and wagons in unusual orders is actually the best top speed-wise.

Note: fix the logic, but keep the system similar to what it is currently. Having double headed trains should not be worse than single headed ones, because that would along with the difficulties of dealing with single track bidirectional systems, discourage them.

I think no matter the locomotive position trains should work the exact same. Especially since we can't rotate or flip locomotives in the depot either.

Locomotives provide power regardless of direction. Double ended (remote power) setups should move the same speed on each direction. I suspect that the behaviour pointed out here is indeed a bug.

There is a max speed penalty for too many wagons pushed, this works as intended

All locomotives contribute to the overall power, note than power and max speed are different things

We may need to display max speed limitation due to construction or wagon order as a separate field to explain this better