This article is about the Class III road numbered C612 maintained by DfI Roads. For other roads numbered C612, see C612.
The C612 is easily Northern Ireland's longest class III route and at a total length of 62km, quite possibly the longest in the whole of the UK. It connects vast swathes of rural County Tyrone on its long journey which starts on the A29 in Cookstown. The road follows Orritor Road westwards out of the town along what used to be numbered as the A53, as far as Orritor itself. The road continues beyond the end of the former A53 westwards and before too long a spur heads south across the upper reaches of the Ballinderry River and links to the A505. Further along another spur links to the A505 at Dunnamore Bridge, albeit a shorter one. After passing through Dunnamore village the road passes through more of an upland landscape as it reaches the southern edge of the Sperrins. Soon another spur turns off to the left and meets the B46 to the west. After this third spur the road turns north west and descends into the upper reaches of the valley of the Owenkillew River. The road follows the main river on its northern side as it turns to the west, crossing over the tributary Coneyglen and Glenlark rivers as it does so. Eventually the road comes to a crossroads from which the route continues north and south. Going north, the road ascends up into Barnes Gap and down the other side to meet the C611. Going south, the road soon swings westwards and continues to follow the Owenkillew River downstream. A spur leads south across the river towards the B46 at Drumlea Bridge. The spur continues southwards from the other side of the bridge and climbs onto the lower eastern slopes of the large and gentle sloping 542m high Mullaghcarn massif. As the road drops back down into the village of Mountfield it TOTSOs south west and via Killyclogher Road and Barony Road it connects to the A505 bypass on both sides of the village. Back at the Owenkillew River, the road soon meets the B48 and continues north westwards from a junction just south of here. This long road finally comes to a long overdue end point on the B47 near Corrickbeg.