Richard Trevethick's work with high pressure steam opened the door to build a compound steam engine that allowed greater expanding of the steam without increasing the temperature in the cylinder. When Arthur Woolf built such an engine with two cylinders in 1811, a 50% savings in fuel consumption occurred. Trevethick also began building compound engines.
With this technology Engineers may build railroads through hills, and Foresters may reach more Timber, improving Timber terrain to Level II and producing three units per turn.
