Wetherbrooke off Camp Highland is one gated community. However, most gates have been torn down in Smyrna because they are more of a hassle than they are worth and if you don't do something like continually leave a car unlocked or garage open with valuables, then nothing usually happens.
Also, all of Smyrna is safe. This isn't Atlanta. There are areas with higher property crime, however most areas that are in the news are unincorporated Smyrna to the North.