A method for detecting a drawbar connecting two motor vehicles (20, 25) moving between a first zone and a second zone, the first zone being separated from the second zone by a control zone the method being implemented by a system having a single control camera configured to acquire at least one image of the control zone, a first camera configured to acquire at least one image of the first zone, and a second camera configured to acquire at least one image of the second zone, the method comprising the steps of: - entry, during which the first camera acquires at least one first image of the first zone. - acquisition, by the control camera, of a single reference image of the control zone, no vehicle (20, 25) being present in the control zone during the acquisition step, - capturing, by the control camera, a two-dimensional working image of the control zone, the capturing step being iterated periodically during the movement of a first vehicle and a second vehicle through the control zone from the first zone to the second zone, a first license plate being a plate at the front of the first vehicle and a second license plate being a plate at the rear of the second vehicle, - recognition, during which the second camera acquires at least one first image of the second zone, and - determining whether there is a drawbar connecting the first vehicle to the second vehicle by using at least one technique selected from: - a first technique comprising the steps of comparing each working image to the reference image, and determining whether a drawbar is present when no working image is identical to the reference image, and - a second technique comprising the steps of recognising the first plate using the first image, recognising the second plate using the second image 25, comparing the two recognised number plates, and determining whether a drawbar is present when the two number plates are not identical. - entry, during which the first camera acquires at least one first image of the first zone. - acquisition, by the control camera, of a single reference image of the control zone, no vehicle (20, 25) being present in the control zone during the acquisition step, - capturing, by the control camera, a two-dimensional working image of the control zone, the capturing step being iterated periodically during the movement of a first vehicle and a second vehicle through the control zone from the first zone to the second zone, a first license plate being a plate at the front of the first vehicle and a second license plate being a plate at the rear of the second vehicle, - recognition, during which the second camera acquires at least one first image of the second zone, and - determining whether there is a drawbar connecting the first vehicle to the second vehicle by using at least one technique selected from: - a first technique comprising the steps of comparing each working image to the reference image, and determining whether a drawbar is present when no working image is identical to the reference image, and - a second technique comprising the steps of recognising the first plate using the first image, recognising the second plate using the second image 25, comparing the two recognised number plates, and determining whether a drawbar is present when the two number plates are not identical. - a first technique comprising the steps of comparing each working image to the reference image, and determining whether a drawbar is present when no working image is identical to the reference image, and - a second technique comprising the steps of recognising the first plate using the first image, recognising the second plate using the second image 25, comparing the two recognised number plates, and determining whether a drawbar is present when the two number plates are not identical.