The City and County of San Francisco will equip nearly 7,600 fleet vehicles with a telematics system following preliminary approval from the Board of Supervisors on Tuesday that includes an exemption for police and fire vehicles following union objections.

The plan is expected to save taxpayers money, reduce collisions, and prompt employees to drive more slowly.

Law enforcement unions had opposed Supervisor Norman Yee's plan, which was proposed in April of 2015. Following negotiations, Yee amended his plan to exempt vehicles used by the Sheriff’s Department, Police Department and juvenile and adult probation departments, according to a spokeswoman for Yee.

"Telematics will increase safety, reduce liability, will be used as a tool to improve driving habits, will help us meet our climate goals, and potentially save lives," Yee said. "I am happy that San Francisco will be joining other jurisdictions in our effort to increase safety and efficiency of our fleet."

Under the plan, about 75% of the city's vehicles would be required to have tracking systems. Telematics systems have already been installed on 39% of the city's vehicles. The city now maintains a contract with USA Fleet Solutions that includes roadside assistance such as 25 miles of towing, fuel delivery, tire changes, and lost or stolen vehicle recovery.

Mayor Ed Lee's budget for 2016-2017 includes $1.7 million to purchase and install the black boxes. The city has also budgeted $1.8 million in annual service fees for training and support. The city plans to produce a safety video for drivers.

To bolster the plan, the city's Budget and Legislative Analyst's Office studied several other agencies' use of the technology, including Yolo County, Riverside County, and Sacramento County. San Francisco's fleet consists of 7,589 units in addition to so-called revenue units such as buses and trollies that have already been equipped with advanced telematics.

The board of supervisors unanimously approved the plan on June 7 and will take a final vote on June 14.