- Power to weight ratio (P/W)
- A ratio that measures the amount of power per weight unit, thus expressing the ability of a train to gain speed and to get over grades. In the U.S. hp/hon (horsepower per ton) unit is used.
- Tons per Operative Brake (TOB)
- A ratio that measures the amount of weight per train vehicle with operative brakes, thus expressing the ability of the train to stop, especially on downgrade.