Hopefully you weren't holding your breath, because thanks to yet another delay, the Bay Area will just have to wait a little bit longer to ride on BART's "Fleet of the Future."

The East Bay Times reports that the California Public Utilities Commission has yet to sign off on "thousands of pages of testing documentation," a process that BART officials believe will take at least 21 days. Until they get the go-ahead from the CPUC that the cars are safe, BART can't run their new cars.

To throw another wrinkle on top of that hassle, several anonymous BART operators spoke with the East Bay Times expressing concern over whether BART management will be ready to let the trains roll even despite this delay — BART had originally said the first new train cars would start taking passengers by late September. Some operators are grumbling that BART hasn't been doing enough to train operators on the new cars.

BART spokesperson Alicia Trost is confident that things will be fine, though, despite the fact that only three percent of operators have completed the full training on the new cars. She said in a statement to the East Bay Times, "As more new cars become available, more operators will be certified to operate the new cars."

As of now, BART is still saying that there will be 20 new cars — two full ten-car trains — in operation by year-end.

Logistically speaking, though, operators point out that scheduling is going to be very difficult until all the operators on a given line have been trained in driving the new trains — because when they get to the end of a line and their shift is over, they can't just hand off a new train with a new system to an untrained operator.

This latest delay with the CPUC is just the latest in a series of frustrating delays with the Fleet of the Future, which is beginning to seem as if it will remain, forever, in the future. Initially, BART had planned on deploying the entire fleet by last December, but in August 2016, they announced that there were still some bugs to work out and production of the trains was slowed. Then, the projected launch date was May 2017. Then, when this past March rolled around, BART announced another delay, saying that thanks to a few implemented changes, the cars were a half-ton overweight and would cause damage to the aging tracks all along the system.

The goal of 20 new cars in operation by the end of the year is revised from the previously stated goal of 35 cars, and if you're keeping track, we still won't see the entire BART fleet replaced until something like 2021, with over 700 train cars still needing to come off the production line by then.

Related: Video: Watch Passengers Poke Around BART's 'Fleet Of The Future'