Think of this as speed bumps for the dead. In locations where there has been a traffic fatality it’s pretty common for a small shrine for the dead to be erected by friends and loved ones. This idea has the location augmented with a small piezo powered transmitter that says the name of the dead and how many days it has been sense the accident. The traffic running over it powers the device. Radios in the local area would be able to pick up these transmissions.