The Transit to Total Station

Surveying fixes the positions of property lines, roads, buildings and utilities. Every building in the museum's chains begins with a surveyor's stake.

Angles and chains

Ancient surveyors laid out right angles with instruments such as the Roman groma. In colonial America, land was surveyed with a magnetic compass and Gunter's 66-foot chain; George Washington worked as a surveyor as a young man. Magnetic compasses are affected by local iron and changing declination, one reason old property descriptions do not always agree.

The transit

In 1831 William J. Young of Philadelphia produced a surveying transit whose telescope could be rotated vertically ("transited") to sight backward and forward on a line. It was fast and accurate enough for the railroad and canal surveys of the nineteenth century. The theodolite, a more precise angle instrument, was used for geodetic and engineering work.

Electronic distance and the total station

Measuring distance with a steel tape over rough ground was slow. From the mid-twentieth century, instruments measured distance by timing light or microwaves. Combining an electronic theodolite with an electronic distance meter produced the total station, which records angles, distances and coordinates. Robotic total stations track a prism so one surveyor can work alone.

Satellites and drones

GNSS receivers (GPS and other constellations), corrected in real time (RTK), give positions to a centimeter or two. Drones with cameras and lidar map sites in hours. In the GIS / Surveying / Drone Operations program, students use all of these, and the data flows into GIS and BIM models (see Measure & Map, Gallery G9).

Credentials

NSPS Certified Survey Technician, FAA Part 107, Esri ArcGIS Pro.