Trunk A-road
A312 traffic and collisions
The A312 is a trunk A-road of 14.7 miles, from Harrow to Richmond upon Thames. This page covers its traffic at 19 DfT count points since 2000 and the collisions police recorded on it.
- Traffic in 2025 185m vehicle miles
- Average daily traffic 34,428 vehicles a day, both directions
- Busiest section 63,188 A4020 Uxbridge rd to A132
- HGV share 3.3% of vehicle miles
- Traffic since 2019 −2.6% same count points
- Collisions, 2021 to 2025 828 96.1 per 100m vehicle miles
How busy is the A312?
On an average day in 2025, 34,428 vehicles passed each point on the A312, counting both directions. The busiest section is A4020 Uxbridge rd to A132 (Hillingdon, Hounslow), with 63,188 a day; the quietest listed is A313 to A311, with 13,562.
Busiest sections, 2025
A4020 Uxbridge rd to A132 carries 1.8 times the road’s average flow.
| Section | Vehicles a day |
|---|---|
| A4020 Uxbridge rd to A132 Hillingdon, Hounslow · 1.3 mi · HGVs 2.7% | 63,188 |
| M4 to A312 North Hyde Rd Hounslow · 0.6 mi · HGVs 4.8% | 55,591 |
| A4 to M4 J3 Hounslow · 1.2 mi · HGVs 4.3% | 54,117 |
| A4180 to A4020 Ealing, Hillingdon · 2.2 mi · HGVs 3.4% | 51,056 |
| A40 to A4180 Ealing · 0.9 mi · HGVs 3.0% | 32,597 |
| A30/A312/A4 to A315 Hounslow · 1.2 mi · HGVs 3.1% | 27,733 |
| A316 to A313 Hounslow, Richmond upon Thames · 0.8 mi · HGVs 1.3% | 25,814 |
| A314 to A316 Hounslow · 0.6 mi · HGVs 3.8% | 25,627 |
| A244 to A314 Hounslow · 1.1 mi · HGVs 3.3% | 21,215 |
| A4090 to A40(T) Ealing · 1.3 mi · HGVs 2.9% | 17,902 |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Route
Harrow to Richmond upon Thames · 14.7 miles
A312 traffic and collisions by section
16 sections between junctions, in route order. Each is the average of its DfT count points, weighted by length.
Show all 16 sections Tap a column heading to sort
| # | |||
|---|---|---|---|
| 1 | A404 to A4005Harrow | 14,170 | 21 |
| 2 | A4005 to A4090Harrow | 15,537 | 61 |
| 3 | At A4090Ealing | 32,856 | 9 |
| 4 | A4090 to A40(T)Ealing | 17,902 | 134 |
| 5 | A40 to A4180Ealing | 32,597 | 98 |
| 6 | A4180 to A4020Ealing, Hillingdon | 51,056 | 79 |
| 7 | A4020 Uxbridge rd to A132Hillingdon, Hounslow | 63,188 | 74 |
| 8 | M4 to A312 North Hyde RdHounslow | 55,591 | 65 |
| 9 | A4 to M4 J3Hounslow | 54,117 | 66 |
| 10 | A30 to A4(T)Hounslow | 39,371 | 21 |
| 11 | A30/A312/A4 to A315Hounslow | 27,733 | 40 |
| 12 | A315 to A244Hounslow | 23,121 | 23 |
| 13 | A244 to A314Hounslow | 21,215 | 45 |
| 14 | A314 to A316Hounslow | 25,627 | 46 |
| 15 | A316 to A313Hounslow, Richmond upon Thames | 25,814 | 32 |
| 16 | A313 to A311Richmond upon Thames | 13,562 | 14 |
Vehicles a day is the average daily flow in 2025. “Since 2019” compares the same count points. Collisions are those with the A312 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.
A312 traffic by vehicle type
Cars and taxis make up 77.6% of the vehicle miles on the A312. HGVs account for 3.3%, rising to 4.8% on M4 to A312 North Hyde Rd.
Vehicle mix, 2025
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
HGV share of traffic
| Year | HGV share |
|---|---|
| 2000 | 4.3% |
| 2001 | 4.5% |
| 2002 | 4.6% |
| 2003 | 4.8% |
| 2004 | 4.7% |
| 2005 | 4.3% |
| 2006 | 4.1% |
| 2007 | 4.6% |
| 2008 | 4.8% |
| 2009 | 3.9% |
| 2010 | 3.9% |
| 2011 | 3.6% |
| 2012 | 4.1% |
| 2013 | 4.3% |
| 2014 | 4.0% |
| 2015 | 3.8% |
| 2016 | 3.9% |
| 2017 | 3.5% |
| 2018 | 3.3% |
| 2019 | 3.7% |
| 2020 | 4.3% |
| 2021 | 4.4% |
| 2022 | 4.3% |
| 2023 | 4.4% |
| 2024 | 3.6% |
| 2025 | 3.3% |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
A312 traffic trend
Traffic on the A312 came to 185 million vehicle miles in 2025. At the count points present in both years, it is down 2.6% on 2019, before the pandemic, and down 3.2% on 2015.
Vehicle miles a year
Like for like, traffic is down 16.0% on 2000.
| Year | Vehicle miles |
|---|---|
| 2000 | 194m |
| 2001 | 193m |
| 2002 | 187m |
| 2003 | 186m |
| 2004 | 183m |
| 2005 | 182m |
| 2006 | 179m |
| 2007 | 173m |
| 2008 | 172m |
| 2009 | 181m |
| 2010 | 182m |
| 2011 | 183m |
| 2012 | 176m |
| 2013 | 174m |
| 2014 | 169m |
| 2015 | 169m |
| 2016 | 167m |
| 2017 | 156m |
| 2018 | 171m |
| 2019 | 177m |
| 2020 | 143m |
| 2021 | 163m |
| 2022 | 171m |
| 2023 | 173m |
| 2024 | 171m |
| 2025 | 185m |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Average daily flow
| Year | Vehicles a day |
|---|---|
| 2000 | 37,928 |
| 2001 | 37,756 |
| 2002 | 36,630 |
| 2003 | 36,394 |
| 2004 | 35,829 |
| 2005 | 35,578 |
| 2006 | 34,980 |
| 2007 | 33,935 |
| 2008 | 33,563 |
| 2009 | 35,434 |
| 2010 | 35,639 |
| 2011 | 35,806 |
| 2012 | 34,389 |
| 2013 | 34,135 |
| 2014 | 33,137 |
| 2015 | 33,054 |
| 2016 | 32,611 |
| 2017 | 32,183 |
| 2018 | 32,963 |
| 2019 | 34,192 |
| 2020 | 27,523 |
| 2021 | 31,393 |
| 2022 | 32,944 |
| 2023 | 33,345 |
| 2024 | 32,935 |
| 2025 | 34,428 |
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 (88.4% of today’s road for 2019). In 2025, 6 of the 19 count points were counted; DfT estimated the rest from earlier counts and local trends.
A312 collisions
Police recorded 828 collisions with the A312 as the first road from 2021 to 2025, 102 of them fatal or serious, including 3 fatal. That is 96.1 per 100 million vehicle miles, higher than the 31.5 for all A-roads in Great Britain. On average there were 11.3 a year for each mile of road.
Reported collisions by year
Up 8.3% from 2021 to 2025.
| Year | Slight | Fatal or serious |
|---|---|---|
| 2021 | 134 | 22 |
| 2022 | 143 | 21 |
| 2023 | 165 | 20 |
| 2024 | 132 | 22 |
| 2025 | 152 | 17 |
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 |
|---|---|
| A4090 to A40(T) Ealing · 134 collisions | 359.0 |
| A4005 to A4090 Harrow · 61 collisions | 195.5 |
| A314 to A316 Hounslow · 46 collisions | 170.3 |
| A40 to A4180 Ealing · 98 collisions | 167.7 |
| A404 to A4005 Harrow · 21 collisions | 115.9 |
| A4180 to A4020 Ealing, Hillingdon · 79 collisions | 112.0 |
| A244 to A314 Hounslow · 45 collisions | 105.7 |
| M4 to A312 North Hyde Rd Hounslow · 65 collisions | 105.6 |
Source:DfT STATS19,UK Motoring analysis 2021 to 2025 Updated
A further 170 collisions were recorded at junctions where the A312 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 A312
In route order. Each is the highway authority DfT files the count points under.
- Harrow
- Ealing
- Hillingdon
- Hounslow
- Richmond upon Thames
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 | 19 count points in 2025 | 15 September 2026 |
| Reported collisions | Road safety open data (STATS19) Department for Transport Derived statistics UK Motoring | 2021 to 2025 | 828 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.