CHICAGO (CBS) — Chicago Transportation Commissioner Gabe Klein — best known for spearheading the mayor’s effort to make the city more bike friendly, and for bringing speed cameras to city streets — is stepping down to return to the private sector.

Klein, 42, said he always planned to leave after about two years of running the Chicago Department of Transportation. He wanted to work in public service for four years, and had two years running the Transportation Department in Washington, D.C., before joining Mayor Rahm Emanuel’s cabinet in May 2011.

READ MORE: Milixen Ardon And Wilfredo Cruz Charged With Murder Of 2-Year-Old Alisson Zelayz, Who Suffered Burns And Bruises In Chicago Lawn

He plans to return to D.C., where his wife lives while working for the federal government.

“Gabe Klein has made a tremendous impact on Chicago and his ideas and leadership have changed the way we approach transportation and made our city a safer place to live, work and play,” Emanuel said in a statement on Klein’s resignation. “I thank him for his dedication to Chicago and endless energy in moving our city forward and wish him success in all his future endeavors.”

READ MORE: Officer Shoots Suspect In Kenosha County, Sources Say Police K-9 Also Wounded

Klein led the effort to bring the Divvy bike sharing program to Chicago, which has grown to approximately 4,000 bikes and 400 docking stations; and he also introduced the first protected bike lanes on city streets.

He also spearheaded Emanuel’s plan to install speed cameras near schools and parks. The cameras are designed to issue tickets to anyone caught going 6 mph or more over the speed limit near parks and schools while they are open.

MORE NEWS: Two Chicago Police Officers Wounded By Accidental Friendly Fire While Confronting Suspect In Lyons, Police Say

The Emanuel administration has estimated $15 million in speed camera revenue for the rest of the year, and $70 million in revenue next year. However, aldermen believe those estimates are conservative, based on the more than 200,000 warnings issued during the first 40 days of testing at four locations this summer. Those warnings would have brought in up to $20 million in fines, had they been actual tickets. The city expects to have speed cameras at 50 locations by the end of the year.