The Chicago Transit Authority is promising a faster, more reliable purple line express by November of this year.

CTA officials and Mayor Rahm Emanuel dropped by the Howard station Thursday to announce a $30 million renovation of the Purple Line tracks between the Lawrence and Jarvis stops in Chicago. This is on top of work that was already done in 2013 to renovate tracks and eliminate slow zones on the same line.

Dorval Carter Jr., recently named president of the CTA, said this would be the biggest investment in the train line that runs from downtown Chicago to the near northern suburbs in the last 40 years.

“By replacing track ties, running rail and other improvements on this century old structure, riders will get a commute that has far fewer slow zones and that is smoother and more comfortable,” Carter said.

CTA officials say around 13,000 passengers ride the Purple Line express each week, which totals up to about 3.5 million riders each year. Carter said normal Purple Line express traffic shouldn’t be affected by the construction, as work will take place solely on weeknights and weekends. The work is also supposed to be out of the way of normal Red Line service, though there may be occasional reroutes.

Construction is set to begin on July 20.

Lauren Chooljian is WBEZ’s city politics reporter. Follow her @laurenchooljian.