Georgia legislators have already spent much of the 2015 legislative session focused on transportation, seeking new revenue to upgrade a struggling system or roads, rail and other infrastructure.

Now, they will also have to deal with a new transportation chief.

Department of Transportation Commissioner Keith Golden is stepping down. Spokesman David Spear said his last day will be Jan. 31.

Golden was a 25-year veteran of the DOT when he took the reins of the agency — and its annual budget of roughly $2 billion — following the September 2011 ouster of Vance Smith.

Since he took the helm, he has faced increasing fiscal challenges with a tight budgets and a growing list of transportation priorities. He also took some heat for his role in the disastrous state response to last year’s Jan. 28 snowy weather, and he was part of the team assigned to make sure it never happened again.

Gov. Nathan Deal’s office had no immediate comment on Golden’s announcement.

Golden said in his farewell letter that he wanted to participate in the work of the Joint Transportation Infrastructure Study Committee, which recently reported that the state would need to find $1 billion to $1.5 billion in new annual revenue just to maintain the state’s faltering transportation system.

“The Study Committee completed their work on the last day of December with a menu of options for consideration,” Golden wrote. “Knowing that I would potentially retire this year, I did not think it would be appropriate for me to be overly active in seeking the much needed funding.”