Complex sentence: These plans were never completed and instead all four busy roads converge at the same level on the single roundabout, made more complicated as the rounabout is currently cut in two by the dual carriageway, which is currently on the same level.
Split into simpler sentences: These plans were never completed and instead all four roads converge at the same level on the single roundabout. The matter is made more complicated as the roundabout is bisected by the dual carriageway on the same level.