ing is also required due to abrasion by ship hulls
Floating ice control
and ice.
Ice problems at navigation locks are primarily
caused by brash ice floating downstream or be-
ing pushed ahead of downbound traffic. The float-
Mechanical ice removal
At many lock installations, ice is removed me-
ing ice pieces can hinder gate opening and clos-
chanically. A frequently used expedient method
ing, adhere to lock walls reducing the effective
lock width, and add significant additional loads
involves scraping the ice off the wall with a back-
to lock gates because of the weight of attached
hoe. The wall is scraped vertically by drawing
ice. Large quantities of ice pushed ahead of a
the bucket teeth up the face of the concrete. With
downbound ship often require an additional lock
a light machine, this may require multiple passes
cycle to clear ice before the vessel can enter.
to scrape down to the concrete, and frequent re-
Attempts have been made to control this ice
positioning of the machine is necessary. With a
by installing pipe manifolds that would allow hy-
heavier, track-mounted machine, a single pass is
draulic flushing while the lower lock gates were
usually sufficient. It is also easier to move the
open (Oswalt 1976). However, this still required
machine along the wall since there are no spuds
additional, time-consuming operations and ex-
to be set. However, with forceful operation, dam-
tra cycling of the lock gates and water levels. If
age to the wall seems inevitable, and serious
ice could be prevented from entering the lock in
spalling of the concrete can occur on grooved or
the first place, most of these problems would not
paneled walls.
occur. A high-flow, high-velocity air screen shown
Inflatable deicers, such as those used on the
in Figure 22 was installed across the upper entry
leading edge of aircraft wings, were tried at the
of the Poe Lock at Sault Ste. Marie, Michigan
Soo Locks to remove the collar from the lock wall
(Itagaki et al. 1975). The device proved effective
but is not used, primarily because of its vulner-
ability to ship-induced damage and its thickness,
which reduces the available lock width.
A 150-hp high-pressure water jet capable of
continuous duty at 10,000 lbf/in.2 was tested and
found to be capable of cutting through a 3-ft-deep
ice collar at a traverse speed of about 3.5 ft/min,
which would require about five hours to clear a
single 1000-ft wall. This approach was dropped
due to its high operating costs (Calkins et al. 1976).
Steam has frequently been used when it was avail-
able at the desired locations, but it too is time
consuming.
Figure 22. Schematic of an air screen.
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