The existence of this road is based on the Antonine Itinerary which mentions a distance of 20 Roman Miles between Bremetennacum and Coccium. The only way this distance can be correct is by a direct line between the two. A route this way however was never identified by 19th century antiquarians or Margary even, but  David Ratledge, on his Roman Roads in Lancashire webpage, presents some possibilities. Here is an extract:-

On the direct route are 4 occurrences of street or causeway names (see map). As yet most are best regarded as possible rather than likely indicators.
If there were a road it would, more than likely, have branched off the Ribchester to Manchester road after crossing the Ribble. There are some very faint traces visible and again ascending obliquely up Mellor Hill in the Lidar imagery but really of low confidence.
At Causeway Farm, near Riley Green, the ford across the River Darwen below Lodge Farm was apparently known as the “Roman Ford”. Any trace of a road seems lost across the golf course but perhaps appears further north across Long Lane at Cabin Hill/Woodcock Hill (Ref: Dixon – Journeys through Brigantia – Book 11). There are some Lidar indications but not overwhelming ones. More work needed.
In 1962 Chorley Arch Soc excavated Heapey Fold Lane south of Healey Nab not far from Kays Farm. This is the only excavation to ever have been carried on this route (that is prior to our excavations at Toddington Lane). At the time though, they were assuming Blackrod to be the Roman station of Coccium. They found a cobbled surface and kerbing heading towards Heapey (in previous years a hoard of Roman coins together with a silver necklace had been found at Heapey, but not exactly sure where). You can see details of Chorley’s excavations here.

Another of David Ratledge’s suggestions is the Common at Adlington, a road which points directly towards Wigan. This route would have crossed the River Douglas at Arley and then, travelling through  Red Rock, would have crossed the Douglas again somewhere near Leyland Mill Lane. In 2015, our attention was drawn to culvert under Wingates Road at the bottom of Leyland Mill Lane which had striking similarities to culverts seen under known Roman roads in north Lancashire. You can see details of our site visit here.

In 2016 Mrs Pendlebury, who lives on Toddington Lane in Haigh, contacted us regarding what she thought was a Roman milestone near her house which had recently been broken. Her claim that it was Roman came from her belief that the lane itself was Roman. We therefore decided we must investigate. You can see details of investigations here.

If we accept the possibility of Toddington Lane being Roman (this route would certainly avoid the double river crossing of the Douglas) then the projected alignment points to the western edges of the ridge on which Blackrod sits. Recent geophysics in the field on the west side of Dark Lane by the Society have failed to find any evidence (see Newsletter No.208) but Alan Bury, a local historian, has obtained permission to excavate which hope to carry out next year. You can see more details of our investigations here.