According to the MBTA, it’s been at least 20 years since the busy subway line, running south from Alewife toward Braintree and back again, was last operating at full speed along the length of its more than 22 miles of track and past its nearly two dozen stations.

The MBTA Red Line is now free of slow zones for the first time in decades thanks to recent track improvements.

The MBTA's Red Line doesn't have any speed restriction zones for the first time in more than 15 years. Why it matters: Getting the T's most popular line into shape has been a long-term goal of MBTA general manager Phillip Eng and the agency's focus on repairs,