Workers are a gang from several areas of the city. They are not an actual gang, just a collection of characters that mostly share the same profession.
In The GameEdit
In Roots, Cleon and Vermin have the option to start a fight with the Workers (namely Erik, Herb and Clinton) to attract The Cops' attention.
In The Best, Tuttle, the only non-construction worker, can be seen in front of The Little Buddha.
In Boys In Blue, Dylan, Luke and Sam are talking with Birdie. They flee when Birdie pulls out his gun after seeing The Warriors.
In Desperate Dudes, Luke and Sam are seen roaming the Checkpoint C area, near the Flash Dealer.