Complex sentence: Thus the track bed itself could only be sold off as one job lot, unless an Abandonment Order were first obtained, which would extinguish the LRO and allow the trackbed to be sold off piecemeal.
Split into simpler sentences: Thus the track bed itself could only be sold off as one job lot, unless an Abandonment Order were first obtained. An Abandonment Order would extinguish the LRO and allow the trackbed to be sold off piecemeal.