Definition
A TRIANGULATION SIGNAL consisting of two separate structures, independent of one another an inner structure which supports the THEODOLITE and sometimes the TARGET or SIGNAL LAMP, and an outer structure which supports the observer and his assistants and sometimes the TARGET or SIGNAL LAMP. Triangulation towers are used to elevate the LINE OF SIGHT above trees, topographic features, and other obstacles that might interfere with the OBSERVATIONS. See BILBY STEEL TOWER.