Regarding helping chicks get the hang of going up the ramp (down is a doddle here, as for ManueB), I have found this sort of arrangement useful.
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The log to left offers staging posts both for up and down, and extension platforms for any 'veer off left on the way up'-inclined chicks, while the green plastic things (actually 'big hands' for leaf collecting) help direct the 'disappear to the right of the ramp, before getting on it, or while part way up it'- inclined chicks. The broody is liable to walk straight up and go into a nestbox, whence she calls, and without being funnelled onto the ramp, the chicks are liable to get as close as they can to the sound, which is directly beneath her, whence they are bemused that they can hear her but not see her, and they don't want to move away from the sound, even if that is the only way actually to reach it.
[To avoid confusion I should add that the photo shows some 2 day old chicks (4 of Gwynedd, Llandeilo, Oxwich, Rhondda and Tintern) venturing out for the first time, not chicks who've actually navigated up and in yet.]