Evening Republican, Volume 59, Number 69, Rensselaer, Jasper County, 23 March 1917 — Air Resistance In Tunnels. [ARTICLE]

Air Resistance In Tunnels.

When a train goes through a tunnel the resistance of the air is an important factor, experiments having demonstrated that it measures 13.86 pounds per ton of train weight in the Simplon tunnel, as against only 83 pounds in the open air, a difference of over 00 per cent. This is when the train is running at 37 miles an hour in the direction of the ventilating air current; when running in the opposite direction the resistance increases to 20.46 pounds.