i just built a rail line to a station at a height of 490 m (so i thought, assuming that water level would be at 0 m), then i ran a train up there. first i thought the achievement would unlock immediately after opening that line, but at first it did not unlock. however, as i ran my train up that mountain, suddenly the achievement was shown to be unlocked exactly 100 height metres before i thought it should happen.

so that offers two conclusions:

1. water level is at 100 m

2. the thick contour lines indeed mark 100 m and thus the thinner lines are spaced at 10 m intervals

we can also deduct from that, according to some rough calculations regarding height lines and track segment length, that the maximum gradient in train fever is about 7 to 7,5 percent and the medium gradient thus is 3,5 to 4 percent. that translates to roughly 1:13 and 1:27 gradients for those used to uk measureing.

the highest mountain peak on the hilly map that i used to test this is 650 m by the way, so you can definately have high ernough mountains yeol.

i had a mistake in my calculation, now i presume the gradients to be around 4.5 % and 2.25 %.

here is how i came up with it:

we know that the contour lines are spaced at every 10 height metres. i then built a piece of track at the maximum inclination between two of these lines with the building cost set to 1 $ per metre. i of course bulldozed this piece of track and rebuild it in order to eradicate terraforming costs. it then costs 215-220 $ to build this piece of track, which should indicate its length. then i used pythagorean math to get the angle of the gradient, which turns out to be 2.6°. this then translates to around 4.5 % for the maximum gradient.

now i don’t know for sure whether there is still an error in there somewhere, but it seems that the trains definately can pull more (at a speed of well over 3 kph) weight than the pulling force figures suggest. it appears that the supplied pulling force might be the force that a locomotive can pull at around half its top speed. at least that about what they did when i tested it with the borsig,g3, ae 3/5 and the nohab.