Dulwich Alliance statement on the data released so far in the Dulwich Streetspace Review
10 August 2021
The absence of data has plagued the Dulwich Streetspace consultation. Although public meetings in May and June were assured that data would be provided during the consultation, the 9 July Dulwich monitoring report was published just two days before the original closing date. So, many of those responding to the consultation will have done so without the benefit of traffic or air quality data: has the Council considered whether those responding before 9 July should be given a further opportunity to comment?
Even though Cllr Kieron Williams, Leader of the Council, stressed – at a meeting with residents’ associations on 19 July – that extensive work was still needed on the data, some representatives of the Council and local councillors are now starting to say that the monitoring shows that traffic levels have reduced as a result of the LTN schemes, both within the scheme areas and on boundary roads (albeit with a couple of exceptions). It seems that the Council, while still insisting the findings are incomplete and the underlying data has not been made available for review, is already moving towards the conclusion that data so far suggests the scheme is successful.
Further data is promised. At the public meeting on 13 July, the Council said that two more tranches of traffic data were due, the first at the end of July and the second at the end of August. Air quality data, they said, would be released by the end of July. So far, none of this has materialised. However, it’s clear that the Council’s preliminary conclusion, based on the data released so far, simply flies in the face of the experience of people living in Dulwich and in the surrounding areas (the extent to which East Dulwich Grove and Croxted Road have been overwhelmed by traffic, for example) and is inconsistent with previous council reports.
This raises major questions about the validity of the baselines and methodology used, how traffic monitoring has been conducted, and what method the Council has used to adjust the results to separate the impact of the Covid lockdown from the LTN measures. (The Council’s July monitoring report simply states, without further explanation, that data has been adjusted to April 2019 levels ‘for a fairer basis of comparison’.)
This lack of transparency raises yet more questions. For example, how will the Council reflect the major traffic changes over school holidays, or the seasonality of cycling? If traffic has gone down – as claimed – on Lordship Lane and on Croxted Road, why are buses delayed? Why does the Calton Avenue, Burbage Road and Turney Road data not correlate with previous OHS data? Have the east and west Turney Road results been muddled up? Why has monitoring shown such a significant increase in HGV vehicles on East Dulwich Grove?
No safe conclusions from the interim monitoring report can be drawn until the raw data has been made available, the robustness of the traffic numbers has been established and the methodology behind the calculations/comparative figures has been made clear.
We set out below what raw data should, at a minimum, be provided. Until it has been published, it will be impossible for the Council – or the local community – to assess properly the impact of the Dulwich LTNs.
- Data back to January 2019 – before the Champion Hill LTN was implemented in February 2019 – so that the effect of this part of the scheme (which produced an extra 1,000 cars on A roads, and an extra 100 cars an hour at peak times on East Dulwich Grove) can be taken into account.
- Vivacity data on Lordship Lane, by hour/day/direction/vehicle type, from April 2020.
- ATC traffic volume counts by hour/day/direction/vehicle type, at all locations (including the abandoned ATC on Lordship Lane).
- Detailed traffic counts on East Dulwich Road past Goose Green, Crystal Palace Road, Peckham Rye, Barry Road, Underhill Road, Friern Road, Denmark Hill, Red Post Hill, Sunray Avenue, and the South Circular.
- Scoot data for all junctions (again, by hour/day/direction) to look at both congestion and volume. It is pointless to look just at overall figures for the whole week, as these hide the peaks, troughs and problem areas: the breakdown has to be by hour and by day of the week.
- Pedestrian data, when it is made available, must be compared with a baseline: it is not clear when Southwark last carried out pedestrian counts.
- All data (but especially pedestrian and cycling data) needs to be closely correlated not only with Covid lockdowns but also with local changes – for example, the opening of the new Tessa Jowell Centre in November 2019, and the expansion year on year of pupil numbers at Charter School East Dulwich since it opened in January 2019.
- Data also needs to be related to traffic light changes (on, for example, Croxted Road) and compared with changes in data on alternative routes.
- Air quality monitoring – not modelling – data for all roads, but especially boundary roads.
- Calculations of increased journey miles on alternative routes once roads were closed – for example, 0.8 miles from South Circular to the junction of Dulwich Village/East Dulwich Grove junction, but 2.9 miles (greater than three times the distance) to get to the same spot via Lordship Lane. These calculations should be related to air quality data and traffic volume and congestion data in order to estimate the likely increase in vehicle emissions in the area as a whole.
During the meeting with residents’ associations on 19 July, Cllr Williams said that the evidence base the Council is using will be completely transparent and that the Council will provide clarification and answer questions on methodology. Several weeks have now passed since he made this commitment, but no raw data has appeared, and no answers have been forthcoming. We look forward to him keeping his word.