Can putting coins on train tracks derail a train?

Can putting coins on train tracks derail a train? Physics says no

Many people wonder can putting coins on train tracks derail a train due to popular cinematic myths. While the physical action results in a flattened piece of metal rather than a catastrophic accident, placing objects on active rails introduces severe personal safety risks. Trespassing near railway infrastructure remains a leading cause of fatal accidents globally.

Can putting coins on train tracks derail a train?

Putting a coin on train tracks cannot derail a train under any normal operating circumstances. This popular urban legend completely ignores basic physics and the vast structural differences between a tiny piece of pocket change and a massive locomotive. A coin is simply flattened or violently deflected, while the train continues onward entirely unaffected.

A standard commercial locomotive weighs approximately 200 short tons, meaning a single wheel can exert immense downward force on the steel rail. ^[2] When a multi-ton wheel traveling at high speed hits a small, soft piece of zinc or copper, the coin acts like putty. The extreme momentum of the train means it doesnt even feel the minor disruption, crushing the coin instantly against the rail like a hammer striking an anvil.

The physics of the penny on train track myth

To understand why a train remains unaffected, we have to look at the massive disparity in mass and momentum. The physical contact point between a train wheel and the rail head is incredibly small - roughly the size of a quarter. This concentrates the weight of the train car onto a tiny surface area, obliterating any small objects in its path through plastic deformation.

The wheel flange also plays a vital role. This specialized steel rim extends over a half-inch below the rail head on the inside of the track, mechanically locking the train wheels onto the guide rails. For a train to derail, the entire wheel assembly must lift completely over this steel lip. A coin measuring a mere 1.55 millimeters thick is mathematically incapable of providing enough vertical leverage to lift a 400,000-pound locomotive flange off the track.

Why you shouldn't put pennies on train tracks

While the train itself is perfectly safe from a coin, anyone standing nearby is in severe danger. Because the top of a railroad track is arched rather than completely flat, a coin rarely sits perfectly balance. When the curved tread of a heavy wheel hits the uneven surface of the coin, it often acts exactly like a penny on train track myth - shooting the object out sideways with immense force.

These flattened coins can easily transform into high-speed projectiles. Driven by the massive energy of the locomotive, a coin can shoot outward from underneath the wheelset at bullet-like speeds. Ive heard harrowing accounts from old railroad workers who watched train track projectile hazards shred through dense nearby brush like a weed whacker. If a piece of metal flying at that velocity strikes a bystander, it can easily cause deep puncture wounds, shatter bones, or result in blindness.

Signal system disruptions and track circuits

Beyond the physical threat of flying metal, placing objects on the rails can cause serious infrastructure damage by blinding the railroads signaling network. Modern railways rely on sophisticated track circuits to track train locations. A low-voltage electrical current is continuously run down one rail, across a relay, and back up the parallel rail. When a train enters the section, its heavy steel axles naturally short-circuit the path, alerting dispatchers that the track is occupied.

When people place multiple coins, metallic tape, or debris on the tracks, they can accidentally mimic this electrical bridge. If the metal contaminants manage to drop the resistance between the two rails enough, it triggers a false occupancy signal. Because railway safety systems are built to fail to a safe state, a false detection will instantly turn surrounding block signals red, forcing oncoming trains to emergency stop and causing massive gridlock across the entire transit corridor.

The real danger: Railroad trespassing penalties

The single greatest threat associated with putting coins on train tracks is the act of getting onto the property itself. Railroad tracks, gravel ballasts, and the surrounding rights-of-way are strictly private property. Walking onto them to place an object isnt a harmless prank - it is a severe safety hazard and a federal crime.

Trains are deceptively quiet and cannot stop quickly. An average freight train traveling at 55 miles per hour requires more than a mile of tracking distance to come to a complete stop after the engineer slams on the emergency brakes.^[1] Pedestrians often misjudge the speed and distance of an approaching locomotive, making trespassing the single leading cause of rail-related fatalities globally, claiming hundreds of lives annually. This is exactly why you shouldn't put pennies on train tracks or wander onto railroad corridors.

Track Obstructions and Their True Derailment Risk

Pocket Coins (Pennies, Quarters)

- Instantly undergoes plastic deformation; flattened into an oval thin sheet.

- Zero risk. Lacks the physical volume to lift the wheel flange.

- Weighs less than 6 grams; under 2 millimeters thick.

- Becomes a high-speed projectile shooting out sideways; extreme risk to bystanders.

Track Switch Debris (Rocks, Thick Branches)

- Prevents track switches from closing completely, creating gaps in the continuous rail.

- Moderate to High. Can force a wheel flange to climb up and out of the proper guide path.

- Varying mass; can jam critical moving infrastructure components.

- Causes localized track structural failures and splits assemblies under moving trains.

Heavy Obstructions (Vehicles, Large Boulders) ⭐

- Exceeds the suspension displacement limits and energy absorption of the locomotive cowcatcher.

- Extreme risk. Forces the front axles completely off the rail head guide path.

- Weighs several hundred to thousands of pounds; significant physical volume.

- Catastrophic high-speed collisions resulting in structural pileups and loss of life.

The Friday Night Prank: A Lesson in Projectile Force

A group of teenagers near a suburban rail corridor decided to test the old myth by placing a row of five quarters on the tracks before the evening commuter express passed through. They huddled behind some light brush just fifteen feet away, expecting to collect perfectly flattened souvenirs.

First attempt: As the locomotive thundered past at seventy miles per hour, the metal coins didn't just quietly flatten. The extreme angle of the wheel treads compressed the coins unevenly against the side of the rail head.

Instead of staying put, three of the coins shot out sideways like ballistic shrapnel. One compressed quarter tore cleanly through the dense brush, striking a teenager squarely in the forearm with immense force.

The incident resulted in a severe deep puncture wound and a fractured radius bone. The group learned the hard way that a train track acts like a high-powered weapon when combined with loose metal debris.