Close-up of temporary trestle for lock construction

Photograph showing concrete delivered to the floor of the lock by being lowered in a hopper (seen suspended just left of the group of men), which was brought from the mixing plant on a car that ran on tracks atop the trestle shown.
Abstract/Description: Photograph showing concrete delivered to the floor of the lock by being lowered in a hopper (seen suspended just left of the group of men), which was brought from the mixing plant on a car that ran on tracks atop the trestle shown.
Subject(s): Boats and boating
Soo Locks (Mich.)
Date Created: 1911 (approximate)