road

In rail terminology, a road is a single railroad track running between two points. It forms the physical path along which locomotives and cars move. A typical mainline road carries trains in one direction only, though at sidings or junctions multiple roads may run parallel to allow traffic in both directions or to separate different services.

Roads are built from steel rails fastened to wooden or concrete ties (sleepers), which are laid on a prepared ballast bed of crushed stone or gravel. Standard gauge roads in North America use 56.5 pound per yard rail with tie spacing of roughly 19 to 21 inches. The rails must be properly aligned in both horizontal and vertical planes; deviations called kinks or dips cause excessive wear on wheels and bearing components.

A single track railroad can only handle one train at a time in each direction, making it a bottleneck for freight and passenger operations. Double-track roads allow simultaneous movement in opposite directions and significantly increase throughput. Branch lines serving industrial sidings or rural areas often use single road construction as a cost-saving measure, accepting the scheduling constraints that follow.

Wear and maintenance challenges

The word road likely derives from older usage describing any traveled way, here applied to the fixed metallic path rather than the route itself. Heavy tonnage gradually deforms the rail head through plastic flow, while impact forces from wheel defects create visible corrugation patterns. Preventive replacement occurs at 400 to 600 million gross tons of traffic, though inspection intervals are typically three to five years.

Switches and turnouts branch off from the main road, allowing cars to be directed onto sidings. Grade crossings where roads intersect with roads at the same level present safety and operational complexity. Proper drainage of the ballast bed is critical; standing water accelerates rail corrosion and reduces bearing capacity of the roadbed, leading to settlement and accelerated wear.