This paper presents the development of a novel decentralized freeway merge assistance system using the Dedicated Short Range Communication (DSRC) technology. The system provides visual advisories on a Google map through a smart phone application. To the best of our knowledge, this is the first implementation of a DSRC-based freeway merging assistance system-integrated with smart phone application via Bluetooth-that has been tested in real-world on an interstate highway in an uncontrolled environment. Results from field operational tests indicate that this system can successfully advise drivers towards a collaborative and smooth merging experience on typical "Diamond" interchanges.