Softwood timber growth in the west and south is approximately in balance with use. Timber is a renewable resource and when managed by professional forest interests, growth can be improved.

Of the 490,000,000 acres of commercial timberland in the United States, 21% is under the control of the Federal government, 6% is controlled by State and Local governments, and 73% is privately held, mostly by small landowners. Of the privately owned timberlands, 14% is owned by the timber industry.

Logging operations are performed by sawmill operations with their own logging crews, or by independent logging con-tractors who sell their harvested logs to the sawmills.

Trees felled and branches trimmed with chain saws. The logs are then ‘skidded’ to a near by concentration point where they are loaded on trucks for transport to the sawmill. Road building and slash control are also involved in logging op-erations.

A logger, usually a small businessman, owns his own equipment which normally would consist of at least a skidder, loader, and log truck.

Sawmills range from simple circular-saw facilities which would conceivably be operated by one person, to large circular-saw and band-saw complexes. Most wood crossties, however are produced by the medium to small size mill, cutting from 50 to 200 crossties per day.

At the mill, logs purchased from independent loggers are "scaled" to assess their expected yield and value. Scaling involves a de-termination of length, diameter, species and quality. Logs are then sorted by species and/or length on the log yard.

The successful operation of a sawmill will depend upon market conditions involving more that just crossties alone.

Almost every log yielding a crosstie will also yield "side lumber." Those lumber by-products of tie manufacturing are used for pallets, flooring, furniture and other miscellaneous lumber uses. The by-products are sold by the mill in very lively and competitive markets which annually use about 7 billion board feet of softwoods. These markets are characterized by many uncertainties including large and unpredictable fluc-tuations in supply and demand.

There is little waste at the modern mill. Outside slab cuts from the log are sold for fuel or charcoal, or, if the logs have been debarked. slabs can be chipped for the paper industry.

Even the sawdust and bark are frequently used for fuel, mulch, or animal bedding material.

Crosstie producing sawmills are tremendously sensitive to market influences, since they generally do not have broad financial backing. Sharp fluctuations in demand for ties and lumber can have serious effects on most mills.

The production of crossties by the industry can involve several completely different concepts in the supply of untreated or treated ties to the railroads.

A few railroads purchase untreated ties from companies engaged in their production and sale, or from sawmills and wholesalers. In turn, they contract with wood preserving companies who process the ties at large plants. Other railroads purchase treated ties on either short or long term contracts from companies who produce ties and treat them at their own wood preserving plants. Most railroads who themselves previously owned such plants have either ceased their operation, or sold or leased the facilities to contract suppliers.

These tie-supply concepts vary from area to area and from railroad to railroad; but those tie-production com-panies, by their pledged involvement in this industry, play an important role in the supply of wood ties to the railroads. While crossties are manufactured by sawmills of all types, most are manufactured by the medium to small independent mills. Many of these mills, while remaining completely in-dependent, rely upon financing from tie-production companies for timber acquisition, equipment pur-chases, maintaining log inventories, and for help in marketing by-products for raw tie manufacturing. These tie producing companies maintain professional field personnel who work closely with the mills to assure the supply of a quality product. Their dedicated involvement in this business, from tree to track, can be extremely helpful both to the independent sawmills on the supply side and to the railroads on the demand side in leveling the peaks and valleys in the tie business.

Regardless of the species of timber used for crossties, if they are to give good service life, the ties must be seasoned properly before being pressure-treated. Seasoning reduces the moisture content of the tie so that the desired penetration of preservative can be achieved during the treating process.

During seasoning, ties develop checks, which are cracks or fissures, in the wood. Seasoning checks release internal pressures and result in better penetration of preservative when the tie is treated.

There are three common processes used to season crossties. Air seasoning involves stacking ties in a manner permitting air to flow freely around and between each tie. Air seasoning will require from 6 to 12 months depending on the wood species and drying conditions. Boultonizing involves the vaporization of moisture in ties using boiling creosote under vacuum. Vapor drying is a technique which vaporizes moisture using hot solvent vapors.

Both vapor drying (12 to 14 hours) and boultonizing (16 to 24 hours) permit immediate preservative treat-ment of freshly cut material but involve relatively high energy costs. The treating process for air dried material is less costly, but inventory costs are higher because of the length of time required for seasoning.

In recent years most roads have ceased the vapor drying process while others have experimented with various chemicals to enhance and perhaps speed up the air drying of ties.

Regardless of the seasoning method, the basic process used for pressure im-pregnation of ties with preservatives is the same.

Generally the purchaser will specify the retention, or number of pounds of preservative per cubic foot of wood to be retained in the tie. Common retentions are 6 to 8 pounds per cubic foot of wood. The preservative is a creosote coal tar or creosote petroleum solution which provides the wood with a number of desirable qualities.

Most crossties are treated by the empty cell process. The average treating cylinder is loaded with 500 to 700 ties on rail trams and the cylinder door is sealed. Air pressure in the cylinder is increased 25 to 70 pounds per square inch, depending on the species being treated. This air not only fills the space around the crosstie, but also enters into the wood and fills the cell cavities within the wood structure.

By maintaining the initial air pressure while the pre-servative is pumped into the cylinder, the air is trapped in the cell cavities of the wood. After the cylinder is filled with preservative, the pressure is increased to 150-200 pounds per square inch.

This pressure is maintained for a period of 4 to 6 hours, until the desired injection of preservative into the wood is achieved.

After the pressure phase of the cycle is completed, the excess preservative re-maining in the cylinder is returned to the supply tank. A vacuum is then drawn on the cylinder for 30 minutes to an hour. As the pressure is reduced from 150-200 pounds to the vacuum level, the air trapped in the cells of the wood expands and forces most of the excess preservative out of the wood. This leaves the cell walls coated with the preservative, rather than leaving the cell cavity filled, resulting in an effective and economic treatment, with little or no excess preservative on the wood surfaces.

Once the treating cycle is completed, the cylinder door is opened and the tie trams are pulled from the treating cylinder onto drip-track areas approved for capturing and recycling of any drippage. The ties are then ready for inspection, loading, and shipment to the customer.