Crossing the A34
The A4185 runs along a short stretch of the former A34 near Didcot that now provides access to the Harwell and Rutherford research laboratories.
The road starts at the Chilton Junction where there is a full-access diamond interchange GSJ with the current route of the A34. It then heads north past the main access to the labs before continuing across open fields to end at a roundabout with the A417 and A4130. The latter continues north along the ex-A34 from here, meeting the current road at a full-access junction.