Trunk A-road
A421 traffic and collisions
The A421 is a trunk A-road of 48.9 miles, from Bedford to West Northamptonshire. This page covers its traffic at 27 DfT count points since 2000 and the collisions police recorded on it.
- Traffic in 2025 621m vehicle miles
- Average daily traffic 34,816 vehicles a day, both directions
- Busiest section 71,980 A421 split to A5134
- HGV share 7.9% of vehicle miles
- Traffic since 2019 +0.7% same count points
- Collisions, 2021 to 2025 342 11.7 per 100m vehicle miles
How busy is the A421?
On an average day in 2025, 34,816 vehicles passed each point on the A421, counting both directions. The busiest section is A421 split to A5134 (Bedford), with 71,980 a day; the quietest listed is A4421 to A43, with 10,351.
Busiest sections, 2025
A421 split to A5134 carries 2.1 times the road’s average flow.
| Section | Vehicles a day |
|---|---|
| A421 split to A5134 Bedford · 2.0 mi · HGVs 7.3% | 71,980 |
| A600 to A6(T) Bedford · 1.9 mi · HGVs 7.7% | 66,139 |
| A5134 to A507 Bedford, Central Bedfordshire · 7.2 mi · HGVs 9.2% | 56,643 |
| A603 to A600 Bedford · 0.7 mi · HGVs 7.9% | 50,936 |
| A603 Bedford · 2.3 mi · HGVs 9.0% | 44,932 |
| A421 North before M1 to A5130 Milton Keynes · 1.8 mi · HGVs 7.6% | 35,700 |
| Grafton St to Rhoscolyn Drive Milton Keynes · 2.1 mi · HGVs 4.0% | 35,095 |
| A507 to A421 North before M1 Central Bedfordshire · 2.2 mi · HGVs 8.5% | 34,742 |
| Count point 92166 Bedford · 4.0 mi · HGVs 11.0% | 33,329 |
| Rhoscolyn Drive to B4034 Milton Keynes · 0.6 mi · HGVs 4.0% | 31,937 |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Route
Bedford to West Northamptonshire · 48.9 miles
A421 traffic and collisions by section
19 sections between junctions, in route order. Each is the average of its DfT count points, weighted by length. 4 short link roads and spurs (1.9 miles) count in the road’s totals but are not listed.
Show all 19 sections Tap a column heading to sort
| # | |||
|---|---|---|---|
| 1 | Count point 92166Bedford | 33,329 | 25 |
| 2 | Count point 92167Bedford | 28,102 | 3 |
| 3 | A603Bedford | 44,932 | 6 |
| 4 | A603 to A600Bedford | 50,936 | fewer than 3 |
| 5 | A600 to A6(T)Bedford | 66,139 | 26 |
| 6 | A421 split to A5134Bedford | 71,980 | 31 |
| 7 | A5134 to A507Bedford, Central Bedfordshire | 56,643 | 33 |
| 8 | A507 to A421 North before M1Central Bedfordshire | 34,742 | 25 |
| 9 | A421 North before M1 to A5130Milton Keynes | 35,700 | 9 |
| 10 | A5130 to Larsborough Rd/Bransworth AveMilton Keynes | 28,589 | 8 |
| 11 | Larsborough Rd/Bransworth Ave to A4146Milton Keynes | 35,736 | 10 |
| 12 | A4146 to A421 splitMilton Keynes | 31,425 | 42 |
| 13 | Grafton St to Rhoscolyn DriveMilton Keynes | 35,095 | 21 |
| 14 | Rhoscolyn Drive to B4034Milton Keynes | 31,937 | fewer than 3 |
| 15 | B4034 to B4033 Nash RdMilton Keynes, Buckinghamshire | 20,806 | 20 |
| 16 | B4033 Nash Rd to A413Buckinghamshire | 16,198 | 11 |
| 17 | At A413Buckinghamshire | 26,106 | 3 |
| 18 | A413 to A4421Buckinghamshire | 26,498 | 12 |
| 19 | A4421 to A43Oxfordshire, West Northamptonshire | 10,351 | 12 |
Vehicles a day is the average daily flow in 2025. “Since 2019” compares the same count points. Collisions are those with the A421 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.
A421 traffic by vehicle type
Cars and taxis make up 76.0% of the vehicle miles on the A421. HGVs account for 7.9%, rising to 13.5% on Count point 92167.
Vehicle mix, 2025
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
HGV share of traffic
| Year | HGV share |
|---|---|
| 2000 | 8.4% |
| 2001 | 8.5% |
| 2002 | 9.0% |
| 2003 | 9.4% |
| 2004 | 8.4% |
| 2005 | 8.4% |
| 2006 | 9.1% |
| 2007 | 9.2% |
| 2008 | 8.7% |
| 2009 | 8.2% |
| 2010 | 8.9% |
| 2011 | 8.6% |
| 2012 | 7.9% |
| 2013 | 7.8% |
| 2014 | 7.6% |
| 2015 | 7.8% |
| 2016 | 7.8% |
| 2017 | 8.0% |
| 2018 | 7.9% |
| 2019 | 7.8% |
| 2020 | 9.2% |
| 2021 | 9.1% |
| 2022 | 8.3% |
| 2023 | 8.1% |
| 2024 | 8.1% |
| 2025 | 7.9% |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
A421 traffic trend
Traffic on the A421 came to 621 million vehicle miles in 2025. At the count points present in both years, it is up 0.7% on 2019, before the pandemic, and up 12.4% on 2015.
Vehicle miles a year
Like for like, traffic is up 37.9% on 2000.
| Year | Vehicle miles |
|---|---|
| 2000 | 362m |
| 2001 | 356m |
| 2002 | 351m |
| 2003 | 348m |
| 2004 | 352m |
| 2005 | 350m |
| 2006 | 365m |
| 2007 | 374m |
| 2008 | 371m |
| 2009 | 366m |
| 2010 | 341m |
| 2011 | 366m |
| 2012 | 430m |
| 2013 | 438m |
| 2014 | 468m |
| 2015 | 492m |
| 2016 | 512m |
| 2017 | 545m |
| 2018 | 569m |
| 2019 | 595m |
| 2020 | 446m |
| 2021 | 527m |
| 2022 | 588m |
| 2023 | 601m |
| 2024 | 584m |
| 2025 | 621m |
Source:DfT,UK Motoring analysis 2000 to 2025 Updated
Average daily flow
| Year | Vehicles a day |
|---|---|
| 2000 | 21,927 |
| 2001 | 21,546 |
| 2002 | 21,281 |
| 2003 | 21,092 |
| 2004 | 21,451 |
| 2005 | 21,323 |
| 2006 | 22,244 |
| 2007 | 22,872 |
| 2008 | 22,668 |
| 2009 | 22,324 |
| 2010 | 20,811 |
| 2011 | 21,972 |
| 2012 | 25,752 |
| 2013 | 26,253 |
| 2014 | 28,062 |
| 2015 | 29,472 |
| 2016 | 30,695 |
| 2017 | 32,174 |
| 2018 | 32,739 |
| 2019 | 34,246 |
| 2020 | 25,853 |
| 2021 | 30,152 |
| 2022 | 33,616 |
| 2023 | 34,375 |
| 2024 | 33,400 |
| 2025 | 34,816 |
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 (50.7% of today’s road for 2019). In 2025, 11 of the 27 count points were counted; DfT estimated the rest from earlier counts and local trends.
A421 collisions
Police recorded 342 collisions with the A421 as the first road from 2021 to 2025, 81 of them fatal or serious, including 5 fatal. That is 11.7 per 100 million vehicle miles, lower than the 31.5 for all A-roads in Great Britain. On average there were 1.4 a year for each mile of road.
Reported collisions by year
Down 16.9% from 2021 to 2025.
| Year | Slight | Fatal or serious |
|---|---|---|
| 2021 | 51 | 20 |
| 2022 | 55 | 18 |
| 2023 | 46 | 16 |
| 2024 | 59 | 18 |
| 2025 | 49 | 10 |
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 |
|---|---|
| A4146 to A421 split Milton Keynes · 42 collisions | 114.4 |
| A413 to A4421 Buckinghamshire · 12 collisions | 25.9 |
| A507 to A421 North before M1 Central Bedfordshire · 25 collisions | 18.8 |
| Grafton St to Rhoscolyn Drive Milton Keynes · 21 collisions | 16.4 |
| A4421 to A43 Oxfordshire, West Northamptonshire · 12 collisions | 15.6 |
| B4034 to B4033 Nash Rd Milton Keynes, Buckinghamshire · 20 collisions | 15.1 |
| A421 split to A5134 Bedford · 31 collisions | 12.2 |
| A600 to A6(T) Bedford · 26 collisions | 11.8 |
Source:DfT STATS19,UK Motoring analysis 2021 to 2025 Updated
A further 91 collisions were recorded at junctions where the A421 was the second road; they are not in the figures above. Fatal or serious uses DfT’s adjusted serious figures. How we count collisions
Council areas on the A421
In route order. Each is the highway authority DfT files the count points under.
- Bedford
- Central Bedfordshire
- Milton Keynes
- Buckinghamshire
- Oxfordshire
- West Northamptonshire
Planned closures on the A421 in England
National Highways has 7 planned closures on the A421 between 16 September 2026 and 30 September 2026, 6 of them starting in that period. 6 close a carriageway rather than a lane or slip road, and 6 start between 7pm and 6am.
-
Carriageway A1 northbound Black Cat Roundabout to Wyboston carriageway closure
-
Carriageway A421 eastbound Water End Interchange to Black Cat Roundabout carriageway closure
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Carriageway A1 northbound Tempsford to Black Cat Roundabout carriageway closure
-
Carriageway A1 northbound Black Cat Roundabout to Wyboston carriageway closure
-
Carriageway A421 eastbound M1 Jct 13 to A6 Marsh Leys carriageway closure
-
Lane or slip A421 eastbound Renhold to Black Cat roundabout (MP 27/0 - 27/5)- lane 2 closure
1 more planned closure in this period are not shown.
Planned closures only: National Highways can cancel or change them, and closures caused by incidents are not shown. Council roads in England are not covered. Roadworks and closures across the UK
Source:National Highways 2026-09-16 to 2026-09-30 Updated
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 | 27 count points in 2025 | 15 September 2026 |
| Reported collisions | Road safety open data (STATS19) Department for Transport Derived statistics UK Motoring | 2021 to 2025 | 342 reported collisions | 15 September 2026 |
| Planned closures | Transport Data Feeds (DATEX II) National Highways | 2026-09-16 to 2026-09-30 | 2,304 planned closure schemes | 16 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.
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