‘L’ System Slow Zone Map January 31, 2016 Notes Overall system slow zones in January 2016 were 5.7% for the month, an increase from 5.5% in December 2015. Slow zones were added to the westbound Green Line tracks near California ahead of future track structure repair work. A portion of slow zones were removed from the Brown and Red lines due to the completion of ongoing track maintenance work. Chicago Transit Authority