Painting yellow cross hatchings on the left side of each step would
be self explanatory, though expensive.
Huh? That ought to mean "Do not use the left side of each step."
Over here cross hatchings on the road mean "do not enter unless your
exit is clear"...

Oh, that kind of cross hatching.

so the principle is the same.

Not really, no.
--
Mark Brader, Toronto | "My ambition is to see a saying of mine attributed
| to Dorothy Parker or Mark Twain." -- Joe Fineman