A method comprises: generating a traffic sign message configured to configure an active traffic sign that is electronically configurable; encrypting the traffic sign message to produce an encrypted traffic sign message; sending the encrypted traffic sign message to a radio broadcast transmitter; and at the radio broadcast transmitter, transmitting the encrypted traffic sign message in a radio broadcast signal; and at the active traffic sign: receiving the radio broadcast signal and recovering the encrypted traffic sign message from the radio broadcast signal; decrypting the encrypted traffic sign message to produce the traffic sign message; and configuring the active traffic sign according to the traffic sign message.