As mentioned earlier, visitor and contractor management systems can also be used to control costs by better monitoring and controlling contractors working at their facilities. The system, for example, can be used to monitor contractor time and attendance by matching the contractor's sign-in and check-out times. During facility outages there can be hundreds or thousands of additional contractors on site, but, with a visitor management system in place, utilities have a reliable mechanism for keeping track of who was there, for what period of time, and whether they were also working at other plants. This can be especially useful for validating the hours contractors claim to have worked, prior to paying them.