Some City of Winnipeg workers are concerned about the use of global positioning systems to keep track of their vehicles.

The city has already installed GPS devices in several of its vehicles, including sanding trucks and street sweepers, and plans to outfit the rest of the fleet. Forestry vehicles are next on the list.

The city says the systems will help improve efficiencies by tracking workers more closely.

"[The city is] looking for a faster response time, and by knowing where the vehicles are they can assign the closest vehicle to a particular call," said Ed Richardson, a communications systems engineer with the city.

The union that represents the workers approves if the GPS is used for tracking routes and improving efficiency and safety, but there is concern the data could be used as a way to monitor workers' movements.

"If they're going to be used for discipline or to micromanage unnecessarily, then of course we would be opposed," said Mike Davidson, president of CUPE Local 500, which represents city employees.