The state Department of Transportation is proposing to keep data for 30 days on how fast people drive under the Massachusetts Turnpike’s new all-electronic toll gantries, raising concern among privacy advocates.
MassDOT officials have said previously that speed data needs to be gathered to synchronize the new tolling system’s cameras so they can snap photos of license plates as cars whiz by.
They have also said they are storing speed data, without identifying information, for research purposes. They reiterated this week there is no plan to use the information to punish speeding motorists.
But the department, for now, is declining to explain why it wants to keep customer-specific speed data for 30 days. Spokeswoman Jacquelyn Goddard said officials want to first present information about privacy and data retention to the MassDOT board at a scheduled meeting Thursday before answering questions.
“Our staff would like to inform the MassDOT Board first on this topic. Then we are happy to answer detailed questions,” Goddard said in a statement.
The department has said previously that it planned to retain tolling data “only as necessary” to accurately charge and collect tolls.
Privacy advocates said the driving public is owed a clear explanation.
The state should say “why it is collecting personally identifiable speed data in the first place, and how it arrived at a 30-day retention period for those records,” said Kade Crockford, director of the Technology for Liberty Project at the American Civil Liberties Union of Massachusetts. “It’s not clear what business purpose the collection and retention of these data serves.”
The advocates worry that Massachusetts could change its mind someday and use speed data — as some other states do — to punish speeding drivers.
They are also concerned that speed and other data captured by electronic tolling could wind up being used against drivers if they are turned over for use in criminal or civil court cases, or stolen by hackers. MassDOT has turned over tolling records when subpoenaed in the past.
The new metal gantries along the Massachusetts Turnpike are scheduled to start collecting tolls on Oct. 28. Toll booths that have bottlenecked traffic for decades are slated to come down.
Drivers will no longer have to stop, or even slow down, to pay tolls. Instead, vehicles with E-ZPass transponders will be charged automatically when they pass under sensors installed on the gantries. Vehicles without transponders will have their license plates photographed by cameras mounted on the gantries, and a bill will be mailed to car owners.
Since testing of the system began in June, it has been quietly capturing information on vehicles that go by, including their speed. Data have been collected from vehicles driving on the Tobin Bridge since the system there was activated in 2014.
All the records have been stored indefinitely. The department has said it does not want to delete any data until it can consult with the state Records Conservation Board, which sets standards for the management and preservation of government records in Massachusetts.
MassDOT is scheduled to bring its proposed “retention schedule” for all-electronic tolling records before the board on Wednesday.
In addition to proposing 30-day retention for speed data, the state is calling for retaining electronic records on toll transactions for seven years. That would include data on the location, date, time, license plate, and transponder number for each transaction, but it would exclude speed data.
Meanwhile, videos of vehicles passing under toll gantries would be kept for 180 days, and images of license plates would be kept for seven years if the license plate imaged was used to process the transaction, or for three months if the image was not used for billing purposes.
Crockford said in an e-mail that several portions of the proposed policy raised red flags.
“Seven years is an awfully long time to amass records showing when and where people have been driving. The longer the retention period, the more data. The more data, the more detailed a story the information tells about individual motorists,” she said.
“Data privacy best practices for industry and government say ‘Don’t collect what you don’t need to fulfill system requirements, and don’t retain information after those needs have been met,’ ” she added.
Crockford said she hopes MassDOT will explain its reasoning behind various aspects of the proposal.
“It’s difficult to assess the privacy-protective value of this policy without more information about why MassDOT thinks it needs to retain these data for so long, and under what circumstances — and with what kind of oversight — outside parties might access them,” Crockford said.