Railroad ties

Railroad ties are traditionally made of wood, but prestressed concrete is now also widely used. Steel ties are common on secondary lines; plastic composite ties are also employed, although far less than wood or concrete.

The first use of prestressed concrete ties in the United States was in 1960 when 500 ties were installed on the Atlantic Coast Line Railroad and 600 ties were installed on the Seaboard Air Line Railroad, followed by 600,000 ties on the combined Sea- board Coastline Railroad. A railroad tie, crosstie, railway tie or railway sleeper, is a rectangular support for the rails in railroad tracks. Generally laid perpendicular to the rails, ties transfer loads to the track ballast and subgrade, hold the rails upright and keep them spaced to the correct gauge.

Tie spacing may depend on the type of tie, traffic loads and other requirements, for example 2,640 rails in the U.S. may be fastened to the tie by a railroad spike; iron/steel baseplates screwed to the tie and secured to the rail by a proprietary fastening system concrete ties per mile on North American mainline railroads. Rails in the U.S. may be fastened to the tie by a railroad spike; iron/steel baseplates screwed to the tie and secured to the rail by a proprietary fastening system. Concrete ties are manufactured with the fastening system integrated into the concrete creating a preset gauge that prevents time consuming measurements and adjustments during installation. A track using concrete ties has greater vertical and lateral stiffness. This drastically reduces maintenance for loose rails and fasteners, and track related derailments are virtually eliminated. Railroads around the world face are facing a decision daily to use concrete or wood as they replace millions of deteriorating wood cross ties used as a base for railroad tracks. In addition, new high-speed passenger rail lines under construction require use of precast concrete ties to obtain desired train speeds. One reason commuter lines prefer concrete ties are to reduce commuting delays caused by track maintenance operations. System operators can almost "set it and forget it" using concrete ties.

Advantages of using reinforced concrete over wood include longer service life, greater strength requiring fewer ties per mile of track and lower maintenance costs. However, while the performance and financial benefits of using reinforced concrete ties have been evaluated, little information is available on the preferred choice from an environmental perspective.

The concrete tie service life ranges from 30 to 50 years, and wood ties from 20 to 30 years. Fully pre-stressed concrete ties have a minimum length of 8'3'' and weigh 600 pounds.

Concrete ties are cheaper and easier to obtain than timber and better able to carry higher axle-weights and sustain higher speeds. Their greater weight ensures improved retention of track geometry, especially when installed with continuous-welded rail.

Concrete ties cost more than wood, but you can use 2,640 concrete ties per mile compared to 3,350 timber ties and they are expected to last.  Through research, concrete-tie manufacturers have managed to overcome problems encountered in anchoring the rail.

Unlike wood and steel, concrete ties do not deteriorate or corrode from exposure to weather. Since they are not coated with creosote like wood ties or have sharp edges like steel ties, they are safer for employees and the environment. They are also noncombustible and lessen the chance of track fire.