Transit authorities in cities across the country are quietly installing microphone-enabled surveillance systems on public buses that would give them the ability to record and store private conversations, according to documents obtained by a news outlet.

The systems are being installed in San Francisco, Baltimore, and other cities with funding from the Department of Homeland Security in some cases, according to the Daily, which obtained copies of contracts, procurement requests, specs and other documents.

The use of the equipment raises serious questions about eavesdropping without a warrant, particularly since recordings of passengers could be obtained and used by law enforcement agencies.

It also raises questions about security, since the IP audio-video systems can be accessed remotely via a built-in web server, and can be combined with GPS data to track the movement of buses and passengers throughout the city.

According to the product pamphlet for the RoadRecorder 7000 system made by SafetyVision, “Remote connectivity to the RoadRecorder 7000 NVR can be established via the Gigabit Ethernet port or the built-in 3G modem. A robust software ecosystem including LiveTrax vehicle tracking and video streaming service combined with SafetyNet central management system allows authorized users to check health status, create custom alerts, track vehicles, automate event downloads and much more.”

The systems use cables or WiFi to pair audio conversations with camera images in order to produce synchronous recordings. Audio and video can be monitored in real-time, but are also stored onboard in blackbox-like devices, generally for 30 days, for later retrieval. Four to six cameras with mics are generally installed throughout a bus, including one near the driver and one on the exterior of the bus.

Cities that have installed the systems or have taken steps to procure them include San Francisco, California; Eugene, Oregon; Traverse City, Michigan; Columbus, Ohio; Baltimore Maryland; Hartford, Connecticut; and Athens, Georgia...