In operations on building sites, nontrailable movable crossings are repeatedly damaged due to a wrong ride. Therefore, Voestalpine Hytronics GmbH sought to design a facility that would warn the operator of a rail bound vehicle of a movable point frog or a turnout that is set wrongly. In operations on track building sites, this warning facility will be mounted temporarily and detect rail bound vehicles approaching critical assets. Once a wrong ride has been detected, a warning will be triggered and displayed by optical and acoustic signalling equipment. In addition, a GSM modem is integrated. This modem, which serves to inform the maintenance personnel, will autonomously send an SMS to freely configurable phone numbers in case of a wrong ride as well as irregularities of the warning facility.