Abstract: An autonomous apparatus for generating real-time estimates of the time of arrival of vehicles at user selected sites. The apparatus is comprised of two separate components, a vehicle unit which is carried by each vehicle and a user unit which is carried by each user. The vehicle unit determines time and geographical position at predetermined locations and broadcast these data to the user units through a wireless communications medium. The user unit receives the time and position information and adds it to computer memory records of similar data received over a prior period of time. The combined set of recorded data is used to estimate the time that the broadcasting vehicle will arrive at a specific location, that location having been specified by the user on a previous occasion by pressing a button on the user unit when the vehicle was stopped at the selected location. The estimated arrival time is presented on a display.