The Grane Road is the road between Blackburn and Haslingden; as 30907 says it crossed under the railway south of Haslingden station. It used to pass the settlement of Haslingden Grane before the village was swept away for construction of reservoirs in the 19th century. I believe that a mineral railway was constructed connecting the works sites with the Accrington to Bury line, but I don't know when it closed. Ogden Reservoir (the middle one of the three) was built in 1912, and an Ordnance Survey map dated 1923 shows the mineral line passing below the dam and heading up into the quarries on the south side of the valley. I don't know if the mineral line was physically connected to the main line or not. However, even if exchange sidings were only provided, some sort of signalling would have been needed, either by signal box or ground frame. Perhaps this is the reference on your map?
Adding to the above.
The Godfrey Edition Map (1909 reprint) cuts off tantalisingly close to the area in question, and the sheet immediately south hasn't been reprinted (or hadn't). However it does show the two running lines and a parallel third line on the west side - presumably a headshunt for sidings - as, at the bottom edge of the map, this third line splits into two. The third line runs north of Grane Road Bridge for a while, has a crossover to the main lines immediately north of the road bridge, and splits immediately south of the road bridge.
I'm struggling with precise detail because I need new specs and there is a ward boundary running down one of the running lines!
The OS Pathfinder map (green cover) shows an area of white where the main line used to run and a wider area of white south of Grane Road - where the sidings referred to above would run to (i.e. on the west side of the line). An indication of former sidings of some kind.
The route of the line to Grane reservoirs / quarries can be followed through field boundaries.
There were several mills in the immediate area, including one on the opposite side of the tracks. These would have coal inbound for the boilers and finished cotton goods outbound. So some demand for a goods yard of some kind.
Further, Hutch Bank Quarry (to the north and still in operation today), had a tramway which ran from the north side of Grane Road, near to the railway bridge, up, into and around the quarry.
As a youth I was fascinated by this old quarry (inactive at the time) where the remnants of the tramway route, and it's tunnels through the spoils heaps could be seen.
On a related topic, I happened to walk (as far as remains possible) the route from Bacup to Rawtenstall just last week.
Hope this helps.