When I am driving I often see people on the side of the road, using some sort of laser-like device. What are they doing? I think they are called surveyors, but that could be totally wrong. AP, I am scared, are they setting up speed traps (or worse)?
ANSWER PERSON RESPONDS: It’s probably worse than speed traps. They’re surveying to widen the highway, resulting in the destruction of trees and historic buildings. The laser device you see is probably a transit. The surveyors point it at a stadia rod or level rod (like a big ruler) to measure heights, angles, and distances from a known point. In the olden days (e.g., 20 yrs ago) the transit was like a telescope, with little crosshairs in it, and you could tell the distance by the magnification of units on the stadia rod. There are a variety of surveying instruments that are sort of like what I describe here (telescope-like, laser-like, measuring rods, etc.). GPS receivers can help with distance nowadays, too.