Where London’s roads are most dangerous

The question

Raw casualty counts make central London look like the most dangerous place to travel, partly because so many people work and travel there. Dividing by residents makes it worse: the City of London has about 7,400 residents but about 360,000 people there on a working day. So I measured casualties against the workday population, the people actually present on a typical weekday, using the 2011 Census, because the 2021 Census took place during lockdown. Then I added the traffic itself as a third measure.

What I did

• Took every collision recorded by the Metropolitan Police and City of London Police from 2010 to 2025 from the Department for Transport’s STATS19 data, and matched each of the 382,744 with a location to the 2011 ward it happened in.
• Counted people killed or seriously injured (KSI), the measure behind London’s Vision Zero goal, using DfT’s adjusted severity estimates. These correct for the Metropolitan Police’s switch to a new injury-recording system in late 2016, which otherwise makes serious injuries jump by about 57% from 2016 to 2017.
• Measured exposure several ways: workday population, residents, people walking to work (2011 Census), and motor, cycle and bus traffic from DfT’s road traffic counts. For boroughs, motor traffic covers all roads; otherwise only major roads have counted lengths, so traffic views compare casualties on major roads with the traffic on them, using only the years in which an area had counts.
• Valued casualties with DfT’s official figures for the cost to society of each one: about £2.6 million per death, £294,000 per serious injury and £22,640 per slight injury, at 2025 prices.

Explore the map

Show

Fatal Serious Slight

Count

People Cost to society

Per

Workday population Residents Motor traffic Cycle traffic Bus traffic Walking to work

Road user

Everyone Pedestrians Cyclists Motorcyclists Car occupants Bus passengers

Areas

Wards Boroughs

Years:

2022 to 2025

20102025

Highest in this view

Area	Rate a year	People a year

Data: DfT STATS19 (2010 to 2025) and road traffic counts (motor, cycle and bus), 2011 Census walking to work, DfT casualty values (RAS4001, 2025 prices), 2011 Census via Nomis, London Datastore boundaries. Base map © OpenStreetMap contributors. Borough logos belong to the councils.

What I found

The way you measure exposure changes the story. Per resident, the City of London, St James’s and the West End are London’s most dangerous wards. Per workday population, the City falls from 1st to 610th of 625 wards, and St James’s and the West End drop below 500th. Per vehicle-km, the order flips back: the City has the highest rate of any borough, about 49 people killed or seriously injured per 100 million vehicle-km from 2022 to 2025, against about 5 in Havering and Hillingdon. Central streets carry little motor traffic for the number of people walking and cycling on them, so each measure tells part of the story.

For cyclists, the riskiest roads are in outer London. Per kilometre cycled on major roads, Bexley, Bromley and Harrow see about 28 to 32 cyclists killed or seriously injured per 10 million km, against about 9 to 12 in the City of London and Camden, and about 15 across London. Risk per kilometre is lowest where the most people cycle, a pattern often called safety in numbers.

On the workday measure, risk concentrates in inner south and west London. Lambeth, Wandsworth, Kensington and Chelsea, Southwark and Richmond upon Thames have the highest borough rates, at about 6 to 7 people killed or seriously injured a year for every 10,000 people there on a workday. The highest ward, Cremorne in Kensington and Chelsea, averages about 13 a year among roughly 8,000 people.

Most of the people hurt weren’t in cars. From 2022 to 2025, pedestrians made up 32% of those killed or seriously injured, cyclists 27% and motorcyclists 21%: four in five were walking, cycling or riding a motorbike.

Some hotspots are through-routes. In two of the top five wards, East Sheen and Ham, Petersham and Richmond Riverside, about three-quarters of those killed or seriously injured were cyclists, which may reflect the popular cycling routes in and around Richmond Park. Many of the people hurt there are passing through, so a population measure overstates the risk to locals.

The cost to society is large. At DfT’s 2025 values, the casualties reported in London cost about £1.9 billion a year from 2022 to 2025, three-quarters of it from deaths and serious injuries.

London’s roads have become safer, but slowly. Killed or seriously injured casualties averaged about 4,660 a year from 2010 to 2012 and about 3,850 from 2022 to 2025, a fall of roughly 17%, while deaths fell from about 140 a year to about 103. That leaves London a long way from Vision Zero’s goal of no deaths or serious injuries by 2041, and 2025 was the worst year since 2018.

Did 20mph limits help?

Many London boroughs have lowered their default speed limit to 20mph. To test whether that cut serious casualties, I compared areas that switched with areas that didn’t, before and after the switch: a staggered difference-in-differences design, first by borough and then road by road.

Dating the switches. I dated each borough’s switch from the data: the year in which the share of its collisions on 20mph roads jumped by at least 20 percentage points to above 40%. That only works from 2017, because the Metropolitan Police’s 2016 recording change also changed how speed limits were recorded. Council and TfL records broadly confirm the dates:

Borough	From the data	Council and TfL records
Ealing	2020	Phases from 2018, the largest in March 2019, completed in March 2020
Merton	2020	Borough-wide roll-out completed in 2020
Richmond upon Thames	2020	Fully in place by March 2020
Kensington and Chelsea	2021	Borough-wide from 13 November 2020
Wandsworth	2021	Side streets from 2017; council A and B roads from 2020
Westminster	2021	Council roads in 2020; TfL roads from 2020 and 2022

The comparison group is the nine outer boroughs where 20mph roads stayed below a quarter of collisions.

By borough, there’s no evidence of a fall. Before the switch the two groups moved together, which supports the comparison. After it, killed or seriously injured casualties in the switching boroughs were about 12% higher relative to the comparison group, but the 95% interval runs from 2% lower to 31% higher, and a placebo test that gives the same dates to random boroughs produces a gap that large 18% of the time. Using the council dates instead gives almost the same answer, about 13% (1% lower to 30% higher). Per vehicle-km the gap is about 16% (1% to 37%), and a placebo gap that large appears only 4% of the time.

Road by road, the answer is the same. A tighter test compares individual roads: each borough’s stretch of every A and B road. 76 stretches switched from mostly 30mph or more to mostly 20mph between 2018 and 2025, and 39 stayed faster throughout. Collisions on the roads that switched barely changed relative to the others (+1%, from 10% lower to 13% higher), and killed or seriously injured casualties rose about 14% (9% lower to 41% higher), within the range of chance. On A roads, where DfT counts traffic, collisions per vehicle-km rose about 15% (1% lower to 31% higher).

What it can and can’t show. Neither test finds the fall in serious casualties that lower speeds are expected to bring. Richmond’s own review found a similar pattern: fewer collisions overall after its switch, but more serious ones. Most switches happened during the pandemic, when travel changed sharply and unevenly across London, and STATS19 records the limit where a collision happened rather than exact road segments. So these results don’t show that 20mph limits fail; they show that their effect on serious casualties isn’t visible in London’s data so far, which is worth understanding before more schemes are evaluated.

How London compares with Toronto

Toronto’s police publish every collision in which someone was killed or seriously injured. Toronto’s definition of a serious (“major”) injury is narrower than Britain’s, so I compare deaths, which are recorded the same way. From 2019 to 2023, Toronto averaged about 52 road deaths a year, 1.9 per 100,000 residents, against London’s 100, or 1.1 per 100,000: Toronto’s rate is about 60% higher. Pedestrians are about half of road deaths in both cities; London loses more motorcyclists and cyclists, Toronto more people in vehicles. London’s rate has drifted down since 2010, while Toronto’s rose to a peak in 2016, the year the city adopted its Vision Zero road safety plan, and has fallen since.

Caveats

• The workday population comes from 2011. London’s daytime population has shifted since, not least with hybrid working.
• Ward figures rest on small numbers: even the highest wards see 10 to 14 people killed or seriously injured a year, so a few collisions can move a ward a long way up or down.
• STATS19 only covers collisions reported to the police, and many slight injuries, especially to cyclists, are never reported.
• The 20mph dates are inferred from the data and checked against council records, not taken from them.
• Cycle and bus traffic only cover counted major roads, and walking to work is a rough, residence-based proxy for pedestrian activity.
• Per-resident comparisons with Toronto use each city’s 2021 census population for every year.

What I’d do next

• Publish the ArcGIS StoryMap version; the layers and draft text are ready in the repo.
• Map Toronto by neighbourhood with the same exposure measures.
• Add TfL’s cycle counts on smaller roads, to fill the gaps in cyclists’ exposure.

This rebuilds and extends the geographic analysis I did for a 2024 LSE group project, which used TfL’s collision feed up to 2019.