- A420 between A4044 and A420 split, Bristol, City of (Grid ref ST597731)
- A420 between Old Market St and Stapleton Rd, Bristol, City of (Grid ref ST598733)
- A420 between Midland Rd and Trinity Rd, Bristol, City of (Grid ref ST600733)
- A420 between Clarence Rd and Stapleton Rd, Bristol, City of (Grid ref ST600734)
- A420 between Trinity Rd and Easton Way roundabout, Bristol, City of (Grid ref ST602734)
- A420 between A4320 and B4467, Bristol, City of (Grid ref ST610733)
- A420 between B4467 and A431, Bristol, City of (Grid ref ST620735)
- A420 between A431 and A4017, Bristol, City of (Grid ref ST640738)
- A420 between A4017 and Bristol, City of boundary, Bristol, City of (Grid ref ST644739)
- A420 between South Gloucestershire boundary and A4017, South Gloucestershire (Grid ref ST646738)
- A420 between A4017 and A4174, South Gloucestershire (Grid ref ST648738)
- A420 between A4017 and A4174, South Gloucestershire (Grid ref ST650738)
- A420 between A4017 and A4174, South Gloucestershire (Grid ref ST658737)
- A420 between A4175 and A4175, South Gloucestershire (Grid ref ST668735)
- A420 between A4175 and A4175, South Gloucestershire (Grid ref ST670735)
- A420 between A4175 and Bath Road, South Gloucestershire (Grid ref ST700728)
- A420 between Bath Road and A46(T), South Gloucestershire (Grid ref ST720723)
- A420 between A46(T) and South Gloucestershire boundary, South Gloucestershire (Grid ref ST750729)
- A420 between Wiltshire boundary and B4039, Wiltshire (Grid ref ST800740)
- A420 between B4039 and A350, Wiltshire (Grid ref ST900745)
- A420 between A350 and B4528 N, Wiltshire (Grid ref ST905742)
- A420 between B4528 Hardenhuish Lane and Park Lane, Wiltshire (Grid ref ST911739)
- A420 between Park Lane and New Rd, Wiltshire (Grid ref ST916737)
- A420 between Marshfield Rd/Audley Rd and Ivy Lane, Wiltshire (Grid ref ST917738)
- A420 between A4 and A420 Split, Wiltshire (Grid ref ST917734)
- A420 between A419 and supermarket roundabout, Swindon (Grid ref SU187865)
- A420 between supermarket roundabout and Swindon boundary, Swindon (Grid ref SU200870)
- A420 between Oxfordshire boundary and A 417 JCT SOUTH Faringdon, Oxfordshire (Grid ref SU237899)
- A420 between A417 and A417, Oxfordshire (Grid ref SU299951)
- A420 between A415 Rnbt Kingston Bagpuize and A417 JCT FARINGDON, Oxfordshire (Grid ref SU400985)
- A420 between A415 Jct Kingston Bagpuize and A 338 JCT, Oxfordshire (Grid ref SP450006)
- A420 between A338 Tobney Wood and A34 Botley, Oxfordshire (Grid ref SP465042)
- A420 between A34(T) and Hollybush Row, Oxfordshire (Grid ref SP499062)
- A420 between Botley Road and Thames St/Speedwell St, Oxfordshire (Grid ref SP508059)
- A420 between A4144 St Aldgates and Speedwell St, Oxfordshire (Grid ref SP513056)
- A420 between Thames St and St Aldgates, Oxfordshire (Grid ref SP513057)
- A420 between Speedwell St and Longwall St, Oxfordshire (Grid ref SP514060)
- A420 between Thames St and Speedwell St, Oxfordshire (Grid ref SP514057)
- A420 between Longwall St and A4158 Iffley Rd roundabout, Oxfordshire (Grid ref SP520062)
- A420 between The Plain and A420 London Rd, Oxfordshire (Grid ref SP550073)