The Meicklejohn and Brown Logging Company near Monroe, Washington, operate over a pole road with three poles for each wheel. The poles are from ten to twelve inches in diameter at the small end and are hewn to a six inch face, giving an eighteen inch bearing surface for each wheel. (See [illustration] on page 29.) The minimum sized pole that should be used for roads of this character is one eight inches in diameter at the small end. The road is constructed the same way as the single pole road and the poles are laid on cross ties twelve inches in diameter placed from eight to ten feet apart. Where the road is off the ground as when crossing over a small depression, these sleepers must not be over five feet apart. The guard rails at this operation are held in place by means of a wooden brace nailed from each end of the rail to a near-by stump. The ends of the poles used for the track are adzed so that they match evenly. By breaking the joints and hewing them the road presents a level surface with no bumps.
In planning the curves, it is necessary to make the tracks somewhat wider than on straight stretches in order to keep the trailer from running off. The track should be three feet wide on sharp curves and provided with a stout guard rail if there is any danger of the truck leaving the track. The curves are banked on the opposite side from that used on railroad curves. That is, the inner rail is raised about three inches. This is to throw the load to the outside away from the inner guard rail, making it easier to make the turn without the rear wheels binding. In this way a 35 degree curve may be negotiated with forty or fifty foot logs. As the curves have to be passed at a much reduced speed, there is little danger of the logs rolling off due to the raised inner rail.
The grading for a road of this construction is usually light. The grades should, if possible, be kept below five per cent. A truck will operate better on a ten per cent grade in dry weather than on a five per cent one in wet weather. On a road of this type, grades up to ten per cent can be operated over unless there is snow. When the grades are above this and the weather is wet, traction still may be secured by sanding the road or by tacking an old half inch steel cable to the road in the form of a figure “s”. If this is sanded in addition, the truck may safely be taken up a steeper grade than it would be safe to bring it down without sanding.
The most common type of motor truck logging road—
a fore-and-aft pole road.
The pole road could be greatly improved by hewing the faces of the poles where they come together side by side so that an even fit is made. The details of this improved form of construction are shown in [figure 1], page 30.
