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LOGGING 
are apt to carry them away. Under such circumstances or where 
the bridge crosses a wide stream the cribs are placed from 20 to 
25 feet apart and the stringers are supported between them by 
piles driven to bed rock at intervals of 8 or 10 feet. 
When the stream is too wide for a single span, the cribs may 
be built in the water, heavily loaded with stone and provided 
with a "rake" on the up-stream face to divert refuse and ice to 
Photograph hy D. A'. Ruucrs. 
Fig. 45. — A Snow Shed on a Two-sled Road. Coniferous brush is placed 
against the framework to prevent the entrance of snow. Maine. 
either side of the crib. When there are long spans it is cus- 
tomary to use five stringers. Deep depressions often are filled 
with cribbing built up to grade level. 
On roads where the snow drifts badly snowsheds are occa- 
sionally built in order to keep the road open with a minimum of 
hand shoveling. They also are used on steep pitches to keep 
the ground free from snow, so that the speed of sleds can be 
controlled. Snowsheds are built in several different forms one 
