A-road
A4020 traffic and collisions
The A4020 is an A-road of 14.4 miles, from Hammersmith and Fulham to Buckinghamshire. This page covers its traffic at 18 DfT count points since 2000 and the collisions police recorded on it.
- Traffic in 2025 120m vehicle miles
- Average daily traffic 22,796 vehicles a day, both directions
- Busiest section 34,417 A4127 Greenford Rd to A3005
- HGV share 2.1% of vehicle miles
- Traffic since 2019 −11.5% same count points
- Collisions, 2021 to 2025 1,172 197.3 per 100m vehicle miles
How busy is the A4020?
On an average day in 2025, 22,796 vehicles passed each point on the A4020, counting both directions. The busiest section is A4127 Greenford Rd to A3005 (Ealing), with 34,417 a day; the quietest listed is Wood Lane / Shepherd's Bush Green to Market Place, with 13,233.
Busiest sections, 2025
A4127 Greenford Rd to A3005 carries 1.5 times the road’s average flow.
| Section | Vehicles a day |
|---|---|
| A4127 Greenford Rd to A3005 Ealing · 0.9 mi · HGVs 3.0% | 34,417 |
| A437 to A408/Oxford Road roundabout Hillingdon · 1.6 mi · HGVs 2.6% | 30,234 |
| At A312 Hillingdon · 2.7 mi · HGVs 1.8% | 28,263 |
| A3005 to A312 Ealing, Hillingdon · 1.3 mi · HGVs 1.5% | 27,438 |
| A3002 to A4127 Windmill Lane Ealing · 0.6 mi · HGVs 2.8% | 20,016 |
| B467 Harefield Rd to M40 Hillingdon, Buckinghamshire · 1.1 mi · HGVs 2.7% | 18,829 |
| A406(T) to A4001 Ealing · 2.1 mi · HGVs 2.0% | 16,695 |
| A4000 Gunnersbury Lane to A406(T) Ealing · 0.7 mi · HGVs 3.0% | 14,513 |
| Wood Lane / Shepherd's Bush Green to Market Place Hammersmith and Fulham, Ealing · 2.0 mi · HGVs 1.4% | 13,233 |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Route
Hammersmith and Fulham to Buckinghamshire · 14.4 miles
A4020 traffic and collisions by section
15 sections between junctions, in route order. Each is the average of its DfT count points, weighted by length.
Sections Tap a column heading to sort
| # | |||
|---|---|---|---|
| 1 | A219 to A3220 Holland Road roundaboutHammersmith and Fulham | 24,251 | 37 |
| 2 | Wood Lane / Shepherd's Bush Green to Market PlaceHammersmith and Fulham, Ealing | 13,233 | 271 |
| 3 | Steyne Rd to Horn LaneEaling | 14,133 | 30 |
| 4 | A4000 Gunnersbury Lane to A406(T)Ealing | 14,513 | 72 |
| 5 | A406(T) to A4001Ealing | 16,695 | 237 |
| 6 | A4001 to A3002Ealing | 19,539 | 18 |
| 7 | A3002 to A4127 Windmill LaneEaling | 20,016 | 27 |
| 8 | Greenford Rd to Windmill LaneEaling | 34,928 | 10 |
| 9 | A4127 Greenford Rd to A3005Ealing | 34,417 | 52 |
| 10 | A3005 to A312Ealing, Hillingdon | 27,438 | 124 |
| 11 | At A312Hillingdon | 28,263 | 192 |
| 12 | At A437Hillingdon | 20,504 | 15 |
| 13 | A437 to A408/Oxford Road roundaboutHillingdon | 30,234 | 56 |
| 14 | A4007/Hillingdon Road roundabout to B467 Harefield RdHillingdon | 28,346 | 17 |
| 15 | B467 Harefield Rd to M40Hillingdon, Buckinghamshire | 18,829 | 14 |
Vehicles a day is the average daily flow in 2025. “Since 2019” compares the same count points. Collisions are those with the A4020 as the first road, placed on the nearest section by their recorded position; rates (per 100 million vehicle miles) are shown for sections of half a mile or more with 10 or more.
A4020 traffic by vehicle type
Cars and taxis make up 78.3% of the vehicle miles on the A4020. HGVs account for 2.1%.
Vehicle mix, 2025
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
HGV share of traffic
| Year | HGV share |
|---|---|
| 2000 | 2.4% |
| 2001 | 2.1% |
| 2002 | 2.2% |
| 2003 | 2.3% |
| 2004 | 2.6% |
| 2005 | 2.8% |
| 2006 | 2.2% |
| 2007 | 2.5% |
| 2008 | 2.5% |
| 2009 | 2.4% |
| 2010 | 2.5% |
| 2011 | 2.6% |
| 2012 | 2.7% |
| 2013 | 3.1% |
| 2014 | 2.9% |
| 2015 | 2.7% |
| 2016 | 2.7% |
| 2017 | 2.4% |
| 2018 | 1.6% |
| 2019 | 1.5% |
| 2020 | 1.9% |
| 2021 | 1.9% |
| 2022 | 2.1% |
| 2023 | 2.2% |
| 2024 | 2.1% |
| 2025 | 2.1% |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
A4020 traffic trend
Traffic on the A4020 came to 120 million vehicle miles in 2025. At the count points present in both years, it is down 11.5% on 2019, before the pandemic, and down 10.2% on 2015.
Vehicle miles a year
Like for like, traffic is down 27.7% on 2000.
| Year | Vehicle miles |
|---|---|
| 2000 | 163m |
| 2001 | 165m |
| 2002 | 161m |
| 2003 | 160m |
| 2004 | 157m |
| 2005 | 149m |
| 2006 | 146m |
| 2007 | 135m |
| 2008 | 138m |
| 2009 | 136m |
| 2010 | 128m |
| 2011 | 129m |
| 2012 | 129m |
| 2013 | 131m |
| 2014 | 130m |
| 2015 | 130m |
| 2016 | 129m |
| 2017 | 128m |
| 2018 | 134m |
| 2019 | 135m |
| 2020 | 108m |
| 2021 | 115m |
| 2022 | 120m |
| 2023 | 119m |
| 2024 | 120m |
| 2025 | 120m |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Average daily flow
| Year | Vehicles a day |
|---|---|
| 2000 | 31,658 |
| 2001 | 32,028 |
| 2002 | 31,181 |
| 2003 | 31,061 |
| 2004 | 30,587 |
| 2005 | 28,989 |
| 2006 | 28,297 |
| 2007 | 26,178 |
| 2008 | 26,734 |
| 2009 | 26,411 |
| 2010 | 24,920 |
| 2011 | 25,103 |
| 2012 | 25,041 |
| 2013 | 25,387 |
| 2014 | 25,183 |
| 2015 | 25,300 |
| 2016 | 25,092 |
| 2017 | 24,830 |
| 2018 | 25,542 |
| 2019 | 25,767 |
| 2020 | 20,468 |
| 2021 | 21,878 |
| 2022 | 22,847 |
| 2023 | 22,725 |
| 2024 | 22,785 |
| 2025 | 22,796 |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
The chart counts the whole road as it was each year, so new or renumbered stretches move it. The percentage changes compare only count points present in both years. In 2025, 6 of the 18 count points were counted; DfT estimated the rest from earlier counts and local trends.
A4020 collisions
Police recorded 1,172 collisions with the A4020 as the first road from 2021 to 2025, 169 of them fatal or serious, including 4 fatal. That is 197.3 per 100 million vehicle miles, higher than the 31.5 for all A-roads in Great Britain. On average there were 16.3 a year for each mile of road.
Reported collisions by year
Down 8.5% from 2021 to 2025.
| Year | Slight | Fatal or serious |
|---|---|---|
| 2021 | 208 | 28 |
| 2022 | 224 | 43 |
| 2023 | 205 | 35 |
| 2024 | 183 | 30 |
| 2025 | 183 | 33 |
Source:DfT STATS19,UK Motoring analysis 2021 to 2025 Updated
Sections with the highest collision rates
Per 100 million vehicle miles, 2021 to 2025. Sections of half a mile or more with 10 or more collisions.
| Section | Per 100m vehicle miles |
|---|---|
| Wood Lane / Shepherd's Bush Green to Market Place Hammersmith and Fulham, Ealing · 271 collisions | 543.5 |
| A4000 Gunnersbury Lane to A406(T) Ealing · 72 collisions | 389.5 |
| A406(T) to A4001 Ealing · 237 collisions | 376.2 |
| A3005 to A312 Ealing, Hillingdon · 124 collisions | 197.0 |
| At A312 Hillingdon · 192 collisions | 140.9 |
| A3002 to A4127 Windmill Lane Ealing · 27 collisions | 123.4 |
| A4127 Greenford Rd to A3005 Ealing · 52 collisions | 91.1 |
| A437 to A408/Oxford Road roundabout Hillingdon · 56 collisions | 62.3 |
Source:DfT STATS19,UK Motoring analysis 2021 to 2025 Updated
A further 119 collisions were recorded at junctions where the A4020 was the second road; they are not in the figures above. Fatal or serious uses DfT’s adjusted serious figures. 100.0% of the collisions could be placed on a section. How we count collisions
Council areas on the A4020
In route order. Each is the highway authority DfT files the count points under.
- Hammersmith and Fulham
- Ealing
- Hillingdon
- Buckinghamshire
Data sources and methodology
| Figures | Source | Period | Records | Updated |
|---|---|---|---|---|
| Traffic counts and vehicle mix | Road traffic statistics (AADF by count point) Department for Transport Derived statistics UK Motoring | 2000 to 2025 | 18 count points in 2025 | 15 September 2026 |
| Reported collisions | Road safety open data (STATS19) Department for Transport Derived statistics UK Motoring | 2021 to 2025 | 1,172 reported collisions | 15 September 2026 |
- Annual average daily flow (AADF) is the average number of vehicles passing a point on a typical day of the year, both directions combined.
- Vehicle miles are AADF multiplied by link length and 365, summed over every count point link on the road.
- Sections join count point links between junctions, using the link lines in DfT’s major road database.
- STATS19 covers personal injury collisions reported to the police. Damage-only collisions are not included, and not every injury collision is reported.
- Serious and slight figures are DfT’s adjusted estimates, which allow for police forces moving to injury-based reporting.
- Counts of one or two collisions below Great Britain level are shown as “fewer than 3”.
Contains public sector information licensed under the Open Government Licence v3.0.