Complex sentence: In Rochester, PA 51/PA 65 meet with Pennsylvania Route 18; the concurrency ends in downtown Rochester, when PA 51 begins a concurrency with Pennsylvania Route 68.
Split into simpler sentences: In Rochester, PA 51/PA 65 meet with Pennsylvania Route 18. In downtown Rochester, the concurrency between PA 51 and PA 65 ends when PA 51 begins a concurrency with Pennsylvania Route 68.