When the majority of your layout consists of 18” modules, you have “Edge Problems”.
A row of bushes helped, but it needed more. The South Philly viaduct really should have a refinery scene behind it but I got tired of viewing long tracks with nothing but “sky” behind them so I added some hills/mountains by taking 1/8’ masonite, painting it dark green, and adding mixes of Woodland Scenices extra course turf, course turf, and a grass blend to it while the paint was still wet. Hairspray and addition “turfs” were added in the second phase. At least now it takes the eye somewhat away from the wall. I still need to hide the viaduct seams with some vine growth.
I repeated the process in North Woodbury and South Westville to add depth to the scenes and hide tree shadows from appearing on the walls during photography.