The B1502 follows part of the original route of the A414 east of Hertford.
The route starts on the A119 to the east of Hertford town centre and heads eastwards through the suburbs along Stanstead Road; this refers to the village of Stanstead Abbots a short distance from the eastern end of the B1502. We soon reach a large roundabout where we meet the A414 and cannon off the A10 and then follow a course parallel to the latter, which is generally hidden in a cutting or behind trees to the left.
It's not long before we bear right then sharply left to run under the A10, after which we follow a straight route along the edge of Great Amwell. The road ends at a roundabout where we rejoin the A414. The B181 now continues along that road's pre-bypass route.