After being in this line of work for a long time, I can recognize a sleeper like an old acquaintance. I can tell the temperament of a piece of wood from its family just by touching and knocking it. Recently, a newcomer in the industry came to me and asked, "Master, why are the sleepers at the turnout wider than ordinary ones? Is it because the wood is not carefully cut?" I laughed when I heard that. It's not because the cutting master is shaking, but because they do it intentionally.
Let's start with ordinary sleepers. An ordinary sleeper, with both ends of similar width, lies neatly beneath the steel rails, like schoolchildren lining up for exercises, with each one in its place without encroaching on others. Its task is simple: to support the steel rails and distribute the weight of the train evenly onto the track bed. If it does a good job, no one pays attention to it; if it doesn't, the entire track will sway.
But turnouts are different. Turnouts are the "crossroads" on the railway, where trains change tracks and diverge, with two rails opening up a gap. The rails run diagonally, and the wooden supports underneath naturally cannot be of average size - the turnout sleepers are incrementally longer or shorter, and from a distance, they resemble an unfolded folding fan. So when you say it's "wider at one end", it actually means that it is longer and stronger than ordinary sleepers, and the longer end must firmly support the rail that is thrown out.
At this point, a problem arises: the longer the wood, the more complex the forces it experiences; the more critical its position, the more susceptible it is to malfunction. The switch area is also a favorite gathering place for rainwater, with numerous gaps and slow drainage. When the wood is soaked there, it will inevitably rot, get infested with insects, and crack. While ordinary sleepers can be replaced if they become damaged, once the switch sleepers fail, the entire line has to be shut down.
When I was young, I used to help my master replace sleepers. It took several people clenching their teeth to move a sleeper for a switch. At that time, I thought, if these wooden sleepers could be less troublesome, how much sweat our workmates would save.
Therefore, the sleepers that can stand on the turnout must be specially trained - pine sleepers that have undergone oil immersion anti-corrosion treatment.
Pine, with its straight grain and uniform texture, is naturally a good candidate for being used as a sleeper. However, even the best candidate cannot withstand decades of exposure to the sun and rain. Therefore, people send it to the "sauna": first, it is dried to remove the moisture from the wood; then, it is vacuumed to expel the air from the cells; finally, preservative oil is injected under pressure. During the vacuuming and oil injection process, the oil penetrates into the pine along its grain, like old soup seeping into tofu, permeating from the inside out. The depth of oil immersion often reaches more than 13mm. Don't underestimate these few millimeters, as they are equivalent to putting a close-fitting and unremovable raincoat on the wood.
After being oiled, the pine wooden sleepers become stable. They won't absorb water, don't like to eat insects, and can't find a place to settle for fungi. The sun can't make them crumble, and freezing rain can't crack them. Even when trains pass over repeatedly, they still firmly support the steel rails. The difference is most evident during rainy season patrols: while ordinary wooden sleepers may have become slightly soft and moldy, the oiled ones still sound solid when knocked.
Even more impressively, the strength and toughness of oil-impregnated sleepers have been elevated to a new level, making them ideal for use in turnouts where complex forces are applied and deformation is not tolerated. They are not afraid to be buried in damp ballast, nor are they affected by the dry cold of the north or the sultry heat of the south. They remain in place throughout the year, silently and reliably performing their duty.
So, we have this scene now: the row of sleepers in the switch area have been lying quietly for decades, neither complaining about being tired nor demanding to be replaced. Ordinary sleepers manage the "straight and simple" straight sections, but they manage the "complicated plot" of the switch.
So, being a bit longer is not a flaw, but a strength. In this day and age, who doesn't have some impressive skills to show off?
