Another set of road safety data shows 20mph limits are a positive change.

Collisions resulting in death or serious injury decreased by a quarter (25%) after speed limits were lowered in London, new data suggests.

Official data from Transport for London (TfL) Road Network (TLRN) reveals the improvements. They come after default speed limits were lowered from 30mph to 20mph.

Capital gains

Figures from TfL also evidence that collisions involving vulnerable road users decreased by more than a third (36%).

The decreases in speed limits across the capital are a key part of the Mayor’s Vision Zero goal. His aim is to  eliminate death and serious injury from London’s transport network whilst encouraging  more walking and cycling.

TfL introduced a 20mph speed limit on all of its roads within the central London Congestion Charging zone in March 2020.  Its Vision Zero commitment is to eliminate death and serious injury on the capital’s roads by 2041.

Growing reductions

Currently, more than half of London’s roads have a 20mph speed limit. It means that almost 110km (68 miles) is part of TfL’s network.

TfL is now working to lower speeds on 220km (136 miles) of its roads by 2024 in inner and outer London.

“Sadly, more than 4,000 people are killed and seriously injured on London’s roads every year,” says Will Norman, London’s walking and cycling commissioner. “Lowering speeds is one of the most important things we can do to reduce road danger and make it easier and safer for people to walk, cycle and use public transport, creating a safer, greener London for everyone.”

Monitoring of the 20mph schemes shows that  the number of collisions has reduced by 25% (from 406 to 304). Collisions resulting in death or serious injury have reduced by 25% (from 94 to 71).

Since the 20mph speed limits have been introduced, collisions involving vulnerable road users have decreased by 36% (from 453 to 290),. Meanwhile, collisions involving people walking have decreased by 63% (from 124 to 46).

Slow down

In 2020, speed was a contributing factor to almost half (48%) of fatal collisions. Since the 20mph speed limits have been introduced across London, there have been reductions of 1.7-5mph across most sites surveyed.

Analysis of journey times, traffic flows and speeds suggest that the 20mph speed limit has not increased congestion, according to TfL.

It says it will be undertaking further quantitative analysis to assess the impact on smoothing traffic flows.