Its actually "Parish Rapid Assessment Team", after 9/11 when DHS was dumping grant money for CBRNE attack/terrorism training, the 6 parishes of Terrebonne, Lafourche, Assumption, St. John, St. Charles and St. James formed the River & Bayou Parishes Mutual Aid & Assistance Task Force. The task force was formed to compete with the bigger metro areas for grant money. They were successful. Basically, each parish has a "team" of 10 people who have received training in hazmat and advanced topics related to terrorism. This grant money has purchased some pretty good response/detection/decon equipment. Its been a while since i've seen one of the trailers, but each parish had a good setup of level A, level B, SCBA, air monitoring, multi RAEs, chemical detection, radiation monitoring, etc., as well as some communication equipment, which is where the channels you see come in. In the grand scheme, the idea was that one (or more) of these teams would be dispatched in the event of an incident to provide rapid assessment, while more resources were being deployed. Keep in mind this area in particular has major amounts of oil/gas production / refineries / terminals / pipelines, etc, that could be major targets.