This article is about the Class III road numbered C557 maintained by DfI Roads.
For other roads numbered C557, see C557
The C557 is a Y shaped route which follows some of the old route of the A6 between Castledawson and Maghera. The road leaves the modern A6 east of Castledawson and crosses the A54 at a crossroads, with past importance evident as the road takes priority over the A54 through the junction. The road eventually comes to Knockloughrim, where the C550 passes through from north to south. To the west of the village a spur leads west back to the A6. The old A6 TOTSOs north from this spur and heads towards Maghera. Another spur heads west to meet the A6 and continues further west to eventually meet the A29. Following the old A6 the road comes to an end on the A42 just outside Maghera, once again with past importance highlighted by the fact that A42 traffic heading east from here has to turn off to continue.