|Length:||9.6 miles (15.4 km)|
|Meets:||A47, A15, A605, A1260, A1(M), A1|
|Route outline (key)|
The A1139 forms the southern and eastern sides of the Peterborough ring road.
The road starts outside the Peterborough urban area on the A47 Eye bypass. It heads south, passing to the west of the village on non-primary S2 before reaching a roundabout in the Newark area of Peterborough. The A15 spur which forms the city's eastern bypass ends here and the A1139 takes on that road's primary D2 status. This being a main road through Peterborough we now gain junction numbers, counting down from J8 at this roundabout.
We now head south on a grade-separated road through the eastern suburbs. There are a couple of GSJs to serve residential areas and industrial estates and presently we cross the River Nene and the Peterborough to Ely railway line. After going over the A605 we meet that road (which is not signed) at a partial GSJ in the Stanground area of town. The two roads run adjacent to the next GSJ, with full access, after which the A605 heads eastwards to bypass Stanground whilst we continue west.
We go over the East Coast Main Line and the A15 before crossing the A1260 at a roundabout GSJ. That road now heads north as the western side of the city ring road whilst we continue on ahead past several suburbs with a two-word name, the first of which is Orton. A spur of the A1139 heads north from Orton Southgate to the A605 in Orton Brimbles, whilst the (shorter) mainline continues ahead to end at the next roundabout, which is A1(M) J17. There is a north- to eastbound sliproad here to bypass the roundabout which goes under the westbound A1139 carriageway to become the right-hand lane of the eastbound carriageway. All four roads at this roundabout have different numbers: ahead is the A605, right is the A1 and left is the A1(M).