The B170 is a short B-road on the edge of London.
The route starts on the A121 in Buckhurst Hill and heads east along Palmerston Road. It crosses the Central Line by Buckhurst Hill station and then leaves the urban area before crossing first the River Roding and then the M11 just to the south of the works unit which occupies the site of the planned, but never built, Chigwell services.
The turn to the left (Roding Lane), immediately after the motorway bridge, is the original route but today we continue straight on along Chigwell Rise, built by a private developer in the 1930s and adopted by Essex County Council as part of the B170 in 1935. The route ends at a mini-roundabout on the A113 in Chigwell about 500 metres south-west of the original Roding Lane terminus, which is by St Mary's church.