"Far more pleasant for walkers and cyclists": 20mph speed limit analysis hailed "astonishing", with drivers' journeys just 45 seconds longer

Initial analysis of the impact of widespread implementation of 20mph speed limits across Wales last week suggests a "dramatic" change in traffic speeds, with the results hailed "astonishing and far greater than would have been predicted".

Rod King MBE, a campaign director at 20's Plenty for Us told Wales Online he hopes the move will make routes "far more pleasant for walkers and cyclists", his comments coming as a report by transport and public health data analysts Agilysis showed an on average reduction in vehicle speed on new 20mph routes of 2.9mph.

Agilysis' Richard Owen said the results were "astonishing" and showed that Welsh drivers had "on the whole" accepted lower speed limits and "have changed their behaviour accordingly".

"There will remain some drivers who choose to break the limit by significant amounts but the drop in speeds on the fastest urban roads has been marked," he said.

> Retired neurologist says increased weight and acceleration of electric vehicles will lead to rise in cycling-related fatalities unless 20mph speed limits are introduced

Agilysis undertook the research after the implementation of the default urban speed limit on 17 September, and collected GPS data from mapping company TomTom to retrieve and analyse speed data within 24 hours of the change.

Looking at the data anonymously provided, Agilysis studied "a very significant sample and more than sufficient for this type of analysis" across a selection of vehicle types — privately owned cars, vans, plus commercial vehicles.

In total, 491.8km of roads that changed from 30mph to 20mph, were analysed across areas such as Cardiff, Newport, Swansea, Wrexham, Rhyl, Merthyr Tydfil, Lampeter, Bangor, Haverfordwest and Newtown. Minor local roads and quiet residential roads were excluded from the analysis as they do not have sufficient sample sizes for the time periods selected.

The headline figure pre-implementation of 20mph speed limits was the average weighted median speed across all the routes was 22.7mph, this dropped to 19.8mph post-implementation.

[Table: Agilysis]

In Cardiff the average weighted median speed dropped from 22.6mph to 19.7mph, while the biggest drop was seen in Rhyl & Prestatyn and Wrexham where the average speeds dropped from 23.2mph to 19.6mph, a reduction of 3.6mph from before the implementation.

[Table: Agilysis] 

The report concluded the change in speed had been "dramatic" and suggested that compliance is "very good". By using results from Cardiff and Wrexham, the report suggests that drivers' journey times were, on average, between 45 and 63 seconds longer.

"The analysis period covered the 6am to 6pm period and compliance is expected to be lower outside of these times," it suggested. "Fewer vulnerable road users (cyclists and pedestrians) are likely to use the roads at these times however and the impact on those killed or seriously injured may be lower. Nevertheless, there are opportunities using this approach to review compliance at different times of the day." 

> James May says 20mph is "plenty fast enough", and hopes "change in attitude" can help end road sectarianism

Rod King of 20's Plenty for Us added: "Our experience from so many implementations across the UK tells us that 20mph limits work, and they work particularly well on the faster urban roads.

"They are not a silver bullet, but do reduce speeds to make streets far more pleasant for walkers and cyclists, they lower faster speeds and produce a more consistent flow of traffic. This in turn makes it safer for all road users. A default urban/village 20mph limit is key to liveability and community life whilst at the same time retaining mobility for all. Well done Wales."

The full report can be accessed here...