Abstract: A roadside, overspeed signal indicator is operated by a moving vehicle. Two vehicle-responsive, detectors are spaced in the direction of travel of the vehicle in a traffic lane and are preferably loop detectors embedded in the traffic lane. An adjustable first timer is in an electrical circuit responsive to the first detector and this electrical circuit, once energized, becomes and remains non-responsive to the first detector until the first timer times out. A signal, electrical circuit is responsive to the second detector if it is energized before the first timer times out. This signal, electrical circuit includes a second timer, so its length of operation in response to a signal from the second detector can be predetermined regardless of the time length of such signal. A counter is provided for counting the number of vehicles operating the first timer and another counter is provided for counting the number of operations of the signal indicator.