In this paper, the use of Software Defined Radio (SDR) transceivers for broadcasting drivers' warning notifications is tackled. More precisely, by employing the Radio Data System (RDS) protocol of a local Frequency Modulation (FM) transmission, road traffic's dangerous areas (rail crossing, unmarked crossroads, etc.) are announced. The code of a warning message is broadcasted in the close vicinity of the dangerous area and, at the receiver side, a corresponding image is displayed on the car's tablet PC. In order to study the coexistence of such kind of transmissions with the regional or national ones, the performance in terms of bit error rate (BER) with respect to the difference between the two received power levels is studied. Then, based on a simplified channel model, this paper gives a method to estimate the local FM transmission range, able to cover the dangerous area without transmission errors on the RDS part.