- A4020 between M40 and Buckinghamshire boundary, Buckinghamshire (Grid ref TQ048850)
- A4020 between Hillingdon boundary and B467 Harefield Rd, Hillingdon (Grid ref TQ052845)
- A4020 between B467 Harefield Rd and A4007/Hillingdon Rd roundabout, Hillingdon (Grid ref TQ053841)
- A4020 between A408/Oxford Rd roundabout and A437, Hillingdon (Grid ref TQ060835)
- A4020 between A437 and A437, Hillingdon (Grid ref TQ072827)
- A4020 between A312 and A312, Hillingdon (Grid ref TQ100814)
- A4020 between A312 and Hillingdon boundary, Hillingdon (Grid ref TQ114807)
- A4020 between Ealing boundary and A3005, Ealing (Grid ref TQ124804)
- A4020 between A3005 and A4127 Greenford Rd, Ealing (Grid ref TQ140802)
- A4020 between Greenford Rd and Windmill Lane, Ealing (Grid ref TQ142802)
- A4020 between A4127 Windmill Lane and A3002, Ealing (Grid ref TQ151801)
- A4020 between A3002 and A4001, Ealing (Grid ref TQ153801)
- A4020 between A4001 and A406(T), Ealing (Grid ref TQ160802)
- A4020 between A406(T) and A4000 Gunnersbury Lane, Ealing (Grid ref TQ189804)
- A4020 between Steyne Rd and Horn Lane, Ealing (Grid ref TQ200801)
- A4020 between Market Place and Ealing boundary, Ealing (Grid ref TQ210800)
- A4020 between Hammersmith and Fulham boundary and Wood Lane / Shepherd's Bush Green, Hammersmith and Fulham (Grid ref TQ232800)
- A4020 between A219 and A3220 Holland Rd roundabout, Hammersmith and Fulham (Grid ref TQ236799)