How many rail spikes should be driven down to eliminate ties on both sides of the joint?

Driving down eight rail spikes is typically the recommended number to effectively eliminate movement of the ties on both sides of the joint. This quantity ensures that each tie is sufficiently secured, preventing any potential misalignment or displacement due to rail expansion, contraction, or load shifts from passing trains. The correct placement and number of spikes distribute the forces evenly along the ties, enhancing the overall stability of the rail joint. This practice is crucial in maintaining safe and reliable railways, ensuring that the joints are stable under operational stresses while prolonging the lifespan of the wooden or composite ties.

In rail construction and maintenance, understanding the need for an appropriate number of spikes is key in achieving optimal performance, thus reinforcing why eight is the ideal answer in this context.