We have DfT traffic speed data from 2019 to 2025 for three segments of the High Road between the junctions, east to west, Goldhawk Road, Chiswick Lane, Heathfield Terrace and Chiswick Roundabout. That allows us to separate out speed changes over each year, both on (the first two segments) and off the route of C9.The biggest drop in traffic speeds along the route of C9 was from 2019 to 2020, before C9 opened. There was a further smaller drop from 2020 to 2021. On the last segment, the situation is reversed. I'm a little surprised that the largest drop occurred on those first two segments during COVID before C9 opened, but the two segments give similar results.So while just looking at changes in speed from 2019 to 2024 might suggest C9 opening was associated with a drop in speeds along the High Road, a more detailed analysis suggests speeds were dropping fastest on that stretch before it opened, and the segment of the High Road that saw the biggest drop in 2021 when C9 opened was beyond C9.Michael is correct, you shouldn't pin blame on the 267 service reduction on one short segment of the route when the general picture of reduced ridership across London is very similar, and the 267 is just one of four services along the High Road. What we do know is that along the High Road motor traffic and pollution have dropped while cycling, footfall and retail spend is up. Of course there are multiple factors that have contributed to these changes, but might it be possible C9 is one of them? In any case, the High Road cannot be described as in any kind of death spiral!
Tom Pike ● 1d