From Markiya R/A, go straight to Immigration R/A (note: do not take the underpass, take the right lane going to Immigration R/A

Then you have to go left at Immigration R/A.

Then take the 1st service road at your right and just go straight (parallel service road of the new highway /Feb 22 road)

Approx 200 meters, you can see the parking area for visitors and visa applicants of US Embassy. Signages are visible as well.

Hope this helps.