County council · England

Road risk in Hertfordshire

Hertfordshire ranks 173 of 192 British highway authorities on our road risk score. Here is what the official record shows, and how it compares.

Lowest riskRisk score 28.3/100ONS code E10000015

Police recorded 1,538 injury collisions in Hertfordshire in 2025, hurting 2,094 people, of whom 349 were killed or seriously injured and 23 were killed. Set against the traffic its roads actually carry, that is 51.1 killed or seriously injured per billion vehicle miles, 37% below the median ranked authority (80.5).

Collisions: 1,538 in 2025
People hurt: 2,094 casualties
Killed or seriously injured: 349
Killed: 23
KSI per billion vehicle miles: 51.1 (median 80.5)
KSI, three-year average: 349.9 a year
Severity-adjusted KSI, 2025: 375 (recorded: 349)
Severity-adjusted KSI, three-year average: 381.9 a year (recorded: 349.9)
KSI per 100,000 residents: 28.2 — rank 141
Population: 1,239,398
Risk score: 28.3/100 — rank 173 of 192

Compiled by Stephen Hall, Data lead, Swift Assist. Source: DfT STATS19 and DfT road traffic estimates (2025), OGL v3. Updated 2026-10-08.

Direction of travel

Five years of collisions in Hertfordshire

Across 2021–2025, recorded collisions were down 3.8%, with 2023 the worst year of the period at 1,813 collisions.

Collisions per year in Hertfordshire

2025: 1,538 (down 6.7% on the year before) · peak 1,813 in 2023 · -3.8% across the period

Axis clipped to the data range to show year-on-year movement.

Two ways of measuring

Hertfordshire looks less dangerous per mile driven than per resident

Divide casualties by the people who live here and Hertfordshire ranks 141. Divide by the miles actually driven on its roads and it ranks 173 — a difference of 32 places.

That gap runs the other way: relative to the traffic its roads carry, Hertfordshire does less harm than its casualty count per resident implies. Places with heavy local travel and few through routes tend to look worse per head than the volume of driving warrants. Neither number is the true one. Which you should use depends on whether you are asking how safe it is to live somewhere or how safe it is to drive there.

Who is being hurt

Pedestrians, cyclists and riders in Hertfordshire

These are the road users with the least protection when something goes wrong, and they carry a disproportionate share of the serious injuries. Across 1,538 collisions in Hertfordshire, the three groups appear 593 times between them — an involvement rate of 38.6%.

Road user	Collisions	Share of all collisions
Pedestrians	217	14.1%
Cyclists	180	11.7%
Motorcyclists	196	12.7%

A single collision can involve more than one of these groups and is then counted in each row, so the rows do not add up to a share of the total.

Darkness, weather and the time of year

When collisions happen in Hertfordshire

DfT records the light level and road surface at every collision, but publishes neither below national level. These are Hertfordshire’s own shares over 4,999 collisions, with the national figure beside each one for comparison.

Share of collisions	Hertfordshire	National	How it reads
In darknessAny collision where the officer recorded darkness, lit or unlit.	26.6%	28.7%	close to the national figure
In darkness, no street lightingThe rural lighting picture rather than the urban speeding one.	5.2%	6.3%	below the national figure
On a wet road surfaceWet, damp or standing water at the scene.	24.9%	24.5%	close to the national figure
On snow or iceRare everywhere, and concentrated in a handful of authorities.	1.1%	1.4%	below the national figure

On the darkness share, Hertfordshire ranks 132 of 192 authorities, counting from the highest.

The winter effect. Collisions in Hertfordshire run 2.3% lower from November to January than from May to July — against 4.5% lower nationally. That is 1,272 collisions against 1,302.

What this does not tell you

A share is not a rate. A high darkness share means darkness accounts for more of Hertfordshire’s collisions — not that its roads are more dangerous overall. Read it alongside the casualties-per-mile-driven figure above.
Condition is recorded, not tested. The officer records the surface and light level at the scene. It is an observation, not a measurement, and it is not a finding that the condition caused the collision.
Exposure is not controlled for. Fewer people travel at 3am than at 3pm, so a collision in darkness is drawn from a smaller pool of journeys. Without hourly traffic counts, these shares describe when collisions happen rather than how risky an hour is.

Every authority compared on the same measures: winter road risk across Britain.

Inside the county

Where the casualties fall across Hertfordshire’s districts

Hertfordshire is the highway authority, but the collisions are spread unevenly across the 10 districts within it.

District	Collisions	Casualties	KSI
St Albans	230	326	47
Hertsmere	223	317	43
Dacorum	161	207	44
North Hertfordshire	158	225	43
East Hertfordshire	157	227	33
Watford	150	181	29
Broxbourne	128	155	35
Welwyn Hatfield	122	160	28
Three Rivers	114	168	28
Stevenage	95	128	19

Benchmark

Hertfordshire against similar authorities

ONS does name statistical neighbours for Hertfordshire, but most of them are lower-tier districts that we do not publish as authority pages — they are not highway authorities, so their road figures belong to the county above them. Rather than compare against pages that do not exist, these are the authorities nearest to Hertfordshire in the national table. That is a weaker comparison and we would rather say so than imply a like-for-like match we cannot actually make. Within this group Hertfordshire is 12 of 21 on casualties per mile driven, against a group median of 53.

Authority	KSI / bn miles	Score	National rank
Rochdale	62.6	29.8	169
Redcar and Cleveland	62	28	175
Aberdeenshire	55.8	27.7	177
Worcestershire	53	28.9	170
West Lothian	53	28.2	174
Hertfordshire (this page)	51.1	28.3	173
Middlesbrough	50.8	28.8	172
Windsor and Maidenhead	38.9	28.8	171
Cardiff	26.7	27.8	176

National position

Hertfordshire against its closest comparators

Hertfordshire sits 173 of 192 nationally, and 139 of 148 within England. These are the authorities nearest to it in the table.

#	Authority	Score	KSI / bn miles
171	Windsor and Maidenhead	28.8	38.9
172	Middlesbrough	28.8	50.8
173	Hertfordshire (this page)	28.3	51.1
174	West Lothian	28.2	53
175	Redcar and Cleveland	28	62

See all 192 authorities →

Common questions

Road risk in Hertfordshire, answered

How dangerous are the roads in Hertfordshire?

In the latest official DfT figures, 1,538 road collisions in Hertfordshire injured or killed 2,094 people, 349 of them killed or seriously injured. Measured against the traffic its roads actually carry, that is 51.1 people killed or seriously injured per billion vehicle miles, against a median of 80.5 across the ranked authorities — placing Hertfordshire 173 of 192 authorities on our combined score, where 1 is the highest risk. The score weighs that rate alongside who is being hurt, the five-year trend and how often a serious collision proves fatal, so the rank is not the rate alone.

Are road casualties in Hertfordshire rising or falling?

Across 2021–2025, recorded collisions in Hertfordshire were down 3.8%, with 2023 the worst year of the period at 1,813 collisions. Year-to-year movement in a single authority is noisy, so the five-year direction carries more than any single year's change.

Who is being hurt on Hertfordshire's roads?

In Hertfordshire there were 217 collisions involving pedestrians, 180 involving cyclists and 196 involving motorcyclists, out of 1,538 in total. Added together that is an involvement rate of 38.6%, though a collision involving two of those groups is counted in both figures, so it is a comparable index rather than a clean share.

Who is responsible for road safety in Hertfordshire?

Hertfordshire is a county council, and is the highway authority for its own roads. That means it sets local speed limits, designs junctions and crossings, and decides safety scheme spending. Motorways and most trunk roads are managed separately by National Highways in England, Transport Scotland, or the Welsh Government, so the worst road in an area is often not the council's to change. Enforcement sits with the local police force.

Where does this data come from?

DfT STATS19, the record police complete at the scene of every injury collision, published annually under the Open Government Licence, combined with DfT's own road traffic estimates for the mileage denominator. Collision, casualty and KSI counts on this page are for 2025; only the trend compares 2021–2025. STATS19 counts collisions police attended and recorded, so collisions never reported do not appear, and under-reporting is known to be worst for cyclists and for slight injuries.

What this means for you

What actually changes the odds in Hertfordshire

Data is only useful if it changes what you do. These three are picked from Hertfordshire’s own figures above, each with the number that prompted it. Every guide explains how the thing works before it suggests buying anything, and most cost less than a third of a typical insurance excess.

Alarmed disc lock

£20–£50

Motorcyclists are in 13% of Hertfordshire's collisions, and bikes are also lifted rather than ridden away. An alarmed disc lock covers the theft half for about £30.

How it works →

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