FOREST RAILROADS 289 
furnish continuous employment for logging engineers while others 
secure their services only when needed. 
Spur lines are located with less care than the main lines for 
they are shorter and of cheaper construction, since they are 
to be used only for a brief period and a limited amount of timber 
is to come out over them. They should follow natural drainage 
in order to provide a down-haul for animal logging, but if power 
skidders are used the roads may be placed on high ground and 
the logs dragged up grade, as it is often cheaper to construct 
and maintain a road on the higher ground, the skidding machine 
will bring logs up grade as easily as down, and the logs do not 
acquire momentum and foul the cable, or catch so readily behind 
stumps or debris. 
In fairly level regions, where animals are used for logging, 
spurs are preferably located so that the maximum haul from any 
part of the operation will not exceed ^ of a mile, except for small 
isolated tracts, which do not warrant the expense of building a 
railroad to them. Where a snaking system is used and the aim 
is to log all parts of the tract by this system, spurs should be placed 
approximately parallel to each other and from 1200 to 1600 feet 
apart, for the maximum efficient radius of the machine does not 
exceed 800 feet. In cypress and other forests where the area is 
logged by the cableway system, the spurs are placed parallel and 
from 1200 to 1400 feet apart. On the West Coast, overhead 
systems often operate for distances of from 1000 to 1200 feet 
from either side of the railroad. In mountainous sections spur 
roads follow main and secondary drainage. Distances greater 
than 3000 feet are not considered desirable for overhead skidding 
systems although the spans may be as long as 4000 feet, when 
the stand is light or railroad construction costs are too high for 
the amount of timber secured. On the Pacific Coast some opera- 
tors build their spur roads to the yarding engines. Where spur 
construction is costly the logs may be brought to the main line 
by road engines, swing donkeys, slides or flumes. In the Appala- 
chian region spur construction is limited, and railroads are con- 
fined to the larger branches of the streams. 
The grades and curves permissible on spurs are greater than 
on main lines because a slow speed is maintained, and lighter 
motive power is used. For the sake of efficiency and safety it 
is always desirable to keep grades and curves as low as possible, 
