Drobeta-Turnu_Severin is a city in Romania.
East towards Bucharest
Walk to the roundabout in the eastern outskirts of the city where the big road going around Severin intersects with E70.
There's some fence (Oct 2020) so you can't stand directly at the roundabout but about 20-30m up the road there's a spot where cars can pull in on the grass (just by the big sign with directions). It's a busy roundabout during day and a line of cars and trucks will build when the big trucks need time to enter the roundabout. It gives the drivers time to pick you up. Definitely bring a sign saying either Calafat/Sofia or Craiova/Bucharest depending on where you're going.
Note that you should stand by the northern entrance to the roundabout, and not along E70 as it's completely fenced up by the roadside.
South towards Sofia
Read the section for going east
Places to avoid
Inside Drobeta-Turnu Severin there's a penny market with a large bus stop in front. Apparently locals hitchhike here sometimes, but it's not a very good spot. Also, people who pulls over are likely to ask for money here.