Not many obstacles till BVRT at least. Earth work was in good progress between Akividu and Vijayawada, largely completed, about an year ago and all small culverts were ready, with only two major bridges on the route, both at BZA outer only. The most persistent obstacle was the lack of funds. :(
A few long distance trains used to run in the loop line earlier too, but they were all crawlers. After MAS-VSKP route started getting doubled and electrified, all of these trains were sped up and diverted via the main line, mainly because of the need for traction change and slower run in the single route. Hopefully, once it becomes FEDL, this line may get back...
more... some long distance trains too!