Low-traffic neighborhoods significantly reduce the number of motorized vehicles within their boundaries without appearing to push traffic onto roads around their edges, the most comprehensive study to date of such schemes in the UK has concluded.

The research, which was based on traffic count data before and after the installation of 46 LTNs in London, found a reduction in motorized traffic within the zones of 32.7% when measured as the median, and a drop of 46.9% when calculated as the meaning.

Of the 413 highways within the LTNs with before and after traffic counts, the percentage experiencing an average of fewer than 1,000 motor vehicles per day, seen as a good shorthand for a street receptive to more bicyclists and pedestrians, increased from 41 % to 66%.

This could mean “a qualitative change in the local environment” on at least some streets due to LTNs, the researchers said.

LTNs use physical filters such as bollards and planters, or traffic cameras to prevent motor vehicles from using some smaller residential streets as through routes, while bicycle and pedestrian traffic remains unaffected.

Opponents of the schemes, which have proven controversial in some places, with a handful removed, say they do not reduce the overall amount of motorized traffic but merely shift it to other roads.

Graph for LTN traffic data

While the authors behind the research, from the University of Westminster’s Active Travel Academy (ATA), noted they only had usable data for just under half of the 96 LTNs installed in London between March 2020 and May 2021. , but they said there was significant overall evidence of so-called traffic evaporation.

Data from the 174 count points on border roads showed what the authors said was a more mixed picture, but with no apparent evidence that border roads would necessarily see more traffic once an LTN was installed.

Of those monitored, 47% showed a drop in motorized traffic and 53% showed an increase. When measured as a mean, the overall average for border roads increased 2.1%, but fell 1.6% when calculated as a median.

When totals were adjusted using Transport for London data for broader traffic changes, to account for factors such as the Covid-19 pandemic and different seasons, border roads had an overall average increase of 0.7% in motorized traffic, or 82 vehicles per day on average.

Within this, the researchers found what they called “substantial variation in both directions” on bordering roads. They concluded that this was mainly due to factors outside the LTN, such as other works, and said that further investigation could be done to reduce traffic on border routes.

The study noted other caveats, including that most counts were carried out in central London rather than the more distant suburbs, and that the scope and quality of traffic data, provided by councils, varied, and some produced no follow-up.

The researchers also noted the need for more study on other effects of LTNs, including how best to mitigate their impact on people who need to drive for local trips, for example, some people with disabilities.

The research was funded by TfL and the climate charity Possible, and carried out by ATA.

Asa Thomas, a PhD researcher at the academy and the study’s lead author, said the findings pointed to a significant drop in motorized traffic within the LTNs, along with “little indication of a systematic shift of this traffic onto border roads.”

Professor Rachel Aldred, director of the ATA and co-author of the study, said: “Research indicates that there has been a general ‘traffic evaporation’ as a result of these schemes, as the average reduction in motorized traffic on internal roads it is about 10 times higher than the average average rise on border roads, adjusting for background trends.

“This suggests that LTNs not only have substantial benefits within their boundaries, but may also contribute to broader traffic reduction goals.”