Comment by pavel_lishin

Another well-sourced story quotes BART Deputy Chief Benson H. Fairow as saying that the "flip was switched" so to speak under his authority, based on the contract that BART has with its wireless providers:

According to Fairow, the statement from BART saying that cell carriers participated in the shutoff isn't precisely it. Fairow says that language in BART's contract with carriers allows BART to "flip a switch" to cut off service for issues of safety. A spokesperson from one of SF's major wireless carriers confirms this, and says that the carriers themselves weren't involved in the shutdown.

"Ultimately, I'm the one that implemented it," said Fairow. "It was certainly run through through channels. A lot of thought went into this."

Source: http://sfappeal.com/news/2011/08/bart-cell-fcc.php

All of the reports that I have seen (including the CNet story linked above) have retracted any statement that the wireless carriers turned off the signal at BART's request.

Pure speculation on my part, but given the limited suitable equipment space available in each BART station, it's likely that BART has deployed a neutral host (i.e., BART-owned, not carrier-owned) distributed antenna system[1] throughout their stations. In that case, it's easy for them to cut power to the actual RF gear without carrier intervention (and without having to worry about those pesky strings of 48V batteries keeping things running.)

The bigger issue to me is that is almost certainly illegal to willfully disrupt 911 service, and it's unlikely that whoever flipped whatever switch, be it disrupting commercial power to carrier-owned base stations or a BART-owned DAS, was able to disrupt texts/voice calls to other parties selectively without disrupting 911 service.

[1] http://www.infinigy.com/PDF/InfinigyNeutralHostWhitepaper.pd...

That would make more sense - I know from renting commercial space (with cell towers on the roof) that the power and service can be independent of the building (i.e. power comes from the street). Maybe that's not true in BART. I'd agree that their "macro-switch" is probably legal (contractual), rather than a physical switch. I'm interested in hearing a file opinion on this, considering that BART is self powered rather than connected to grid(s) the cities it serves?

I would not be surprised if carriers rented space from BART to deploy equipment and antennas. Which would make BART the landlord, and provider of electrical power.