Impersonal constructions in Russian

[Mark Knighton]

Dear Colleagues,

A Czech-speaking linguist has asked me to inquire about impersonal
expressions in Russian of the sort: "dorogu zaneslo snegom" or "trup
uneslo rekoj" (These are discussed briefly in T. Wade, A Comprehensive
Russian Grammar pp. 320-321.)

The question is this: do these expressions ever appear in the non-past?
Beyond that, can they be considered productive?  Commentary in
conventional grammars is minimal.
Any examples and/or comment from native speakers would be most welcome.

Sincerely,

M. Knighton