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Bridge Crossing Problems Calculator

Online train-bridge problem calculator. Enter train length, bridge length and speed to find both the time to fully cross and the time fully inside the bridge—ideal for motion word problems.

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Fully cross=(train+bridge)/speed; fully on=(bridge−train)/speed
Train
Bridge
Speed

📖 Tutorial | Train Crossing

1. Definition
Distinguish fully crossing from being fully on the bridge.
2. Formula & Notation
Fully crossFront in to rear out
Fully onRear in to front out
3. Properties & Laws
  • Distance train+bridge;
  • On: bridge−train;
  • Time=distance/speed;
  • Consistent units.
4. Steps
  1. Enter L, B, v;
  2. Click "Calculate";
  3. Or click "Load Example".
5. Worked Examples
Example: 120, 880, 20.
Solution: cross 50, on 38.
6. Common Pitfalls
Add train length;
Short bridge no on;
Unify units.

❓ FAQ | Train Crossing

Why add train?
Rear must clear.
120,880,20?
50 and 38.
Fully on?
Bridge−train.
Units?
÷3.6.
Speed?
Distance/time.
Short bridge?
No on.