Air carrier First Officer reported needing to avoid tug drivers that have been intruding into the Ramp Area due to the lack of clear road markings for the G; H; K; and L gates at ORD Airport.

Narrative

Hello; I would like to submit a general safety concern. I am a FO based in ORD and have flown over 700 hours now in and out of ORD. My concern is the missing access road markings in certain Ramp areas. I noticed all of Terminal 1; and all E and F gates have access roads painted to allow luggage tugs; fuel trucks; catering trucks; etc.; a safe way to move around the Ramp without interfering with aircraft movement. These road markings are not marked for all G; H; K; and L gates. I have had numerous times seen luggage tugs drive straight over the Ramp and sometimes double or triple stack behind aircraft at the gate; thus bringing them more intruding into the Ramp Area. There needs to be clear access road markings behind the gates in Terminal 3 and G gates. We have had to stop before because a tug was way behind the gate driving and clearly in our path of movement in the Ramp Area. Since there are no markings right now; tug drivers don't have a boundary to reference and go beyond the limits of driving in the Ramp Area. Soon or later there's going to be a wing tip hitting a tug; even though the aircraft is on the line. Clear road markings painted behind the gates would make it easier for tugs to see where they are allowed to drive.