The B1518 follows the pre-bypass A15 out of Sleaford to the north.
The road starts in Sleaford town centre at the northwest corner of the B1517 one-way loop. We head north, initially along a road no wider than the B1517 we have left but two-way traffic has to be fitted in.
The road widens out as it reaches the suburbs. It goes over the Sleaford to Lincoln railway line and then passes through the suburb of Holdingham. After a roundabout serving a new housing estate the road ends at the next, much larger roundabout, where the A15 western bypass meets the A17 northern bypass.