duckboard

One of a long series of boards laid from side to side as a path across wet or muddy ground; normally used in plural.

“In an attempt to alleviate the problem, wooden planking, known as duckboards, was placed at the bottom of trenches and across other areas of muddy or waterlogged ground.”

Wooden, low walkway or short part of a path with one or more planks, logs, or boards laid after each other lengthwise, often two planks wide; also called bog board, bog bridge, or puncheon.