rail spike
A type of large nail with an offset head used to fasten a rail or base plate to a wooden railroad tie/sleeper.
rail spike: the nail that holds track to timber
A rail spike is a heavy steel fastener, typically 5 to 6 inches long, driven vertically through a rail's base plate and into a wooden railroad tie (or sleeper) to anchor the rail in place. The spike has a large, flat head offset at an angle, which bears down on the plate rather than sitting flush. This geometry allows the head to grip the plate firmly and distribute clamping force across a wider area.
The offset head is the spike's defining feature. Unlike a straight nail, the head is tilted so that when driven vertically, it clamps the rail plate tightly against the tie. Spikes come in different weights and lengths depending on rail type and tie size. Common weights range from 1 pound to 1.5 pounds for standard-gauge track on hardwood ties. Steel composition is chosen to resist bending and shearing under the dynamic loads of passing trains.
A rail spike is driven by hammer or pneumatic spike driver in a predetermined pattern, typically four spikes per tie (two per rail). Over time, repeated vibration and impact from train wheels work the spike loose. Track workers perform routine spiking, tightening existing spikes that have settled or pulled slightly from the tie. Loose spikes are a safety issue because they allow the rail to shift laterally under load, risking derailment.
The wood tie eventually splits, crushes, or rots around the spike hole, reducing holding power. When ties decay, spikes may pull free entirely. This is why rail maintenance crews regularly inspect spike condition and replace spikes in weakened ties. Modern practices on some lines have shifted toward elastic fastening systems (resilient clips and pads) that require no spiking, but millions of miles of track still rely on traditional spikes.
The term 'spike' derives from its resemblance to a tapered metal spike or wedge, though railroad spikes have always had heads. The offset head design is sometimes called a 'dog-ear' spike in older texts because the tilted head suggests ears. Spikes remain one of the cheapest and most reliable fasteners in rail infrastructure, requiring only a hammer and labor to install or repair, which ensures their use will continue for decades on secondary and rural lines.