On 25 June, 08:01, Matty F wrote:

a thin wooden gate of that width is basically impossible.

Obviously it's not impossible, but there comes a point when wider
gates of thinner scantlings become awkwardly flexible.

The fix for this on level crossing gates is to use a wire truss
structure as well. The "gate" is wooden and flexible. Along the bottom
edges (both side) are a series of iron "pylons" sticking out about 6"
from the wood. Diagonal wire bracing beween these (usually taken under
the wood, from side pylon to side pylon) makes the effective thickness
of the gate 12"-18" and thus a lot stiffer.