Rails are fairly ubiquitous whether for tramming out produce or waste. The term "drainage adit" will refer to the lowest level of natural drainage, shafts often pumped to that level. What looks unusual in this example is the absence of a channel for the water, this enables people using the level to keep their feet dry.
The care taken with the stone arching is not unusual, its quite prolific in the north Pennines, but other good examples to be seen in Wales. Talybont deep adit for example. Usually where the level passes through bad ground in Wales, or sometimes 'cut and cover' entrance section. North Pennines its oftern where the level passes through stopes and backfilled on top.