This method makes it possible to characterize the seat of a railroad track through penetrometric and geo-endoscopic tests. It includes steps consisting of striking ram head of a light dynamic penetrometer to drive the tip of a train of rods into the seat, measuring the strength of the seat as a function of the pushing in depth of the train of rods, removing the train of rods from the seat, pushing a tube into a hole left by the train of rods, and sliding an image-recording camera inside the tube. The method includes additional automated steps consisting of measuring the position of the camera while it slides inside the tube, i.e., the dep that which the images are recorded, and couplingan analysis of the recorded images as a function of the depth with the strength measurements of the seat to characterize the different layers of the seat.