In 1964 the line at Blodwell Junction was cut back from the point at which the Nantmawr branch to Lllanymynech diverged from the Tanat Valley Light Railway line to Llangynog to the east side of the A495 road bridge. The buffer stops were located at the point where the Blodwell Junction station goods facilities had been.

This meant that the original line from Nantmawr and the 1904 Tanat Valley line from Porthywaen joined each other as single track railways with no run around facilities as there had been on the west side of the A495 road bridge. Mineral trains coming from the quarries on the Nantmawr line therefore had to stop short of the junction with the Porthywaen line. The engine was then uncoupled and it ran through the junction where it reversed onto the Porthywaen line. With the aid of a brake van the wagons were then gravity worked through the junction. The locomotive was then able to back onto the wagons and it was facing the right way to continue its journey northwards through Oswestry and on to Gobowen. In the reverse direction empty wagons had to be propelled for a short distance onto the Nantmawr branch where there were sidings that allowed a run around move to be made.

On 21 October 1971 stone traffic ceased to run from Nantmawr Quarry but it continued to operate from Llanddu Quarry which was served by sidings on the Nantmawr branch close to its junction with the Porthywaen line. Therefore the same method of gravity working had to continue.

To eradicate the gravity working British Rail installed a run around loop at Blodwell in 1985. The western end of the loop was close to the site of the Blodwell junction station goods facilities. The eastern end was on the Porthywaen line just to the east of the junction. The line was extended at its western end right up to the A495 road bridge.

The run around loop had a relatively short life as rail traffic ceased to run from Llanddu Quarry in 1989.