Data

Traffic Data Analysis

The impact of school holidays on traffic in the local area has consistently been visually observed throughout West Dulwich. We are investigating these trends, using available data, so we can better understand what is happening and then help generate solutions.
 

The graph shows Autumn/Winter 2021 term data for Croxted Road from the TFL SCOOT system (we await data sets for Turney & Rosendale road). In this term,  most non catchment schools began half-term holidays on 18 October (the first black data point), state schools began half-term on 25 October (the second black data point). All schools returned on Nov 1st.

Our analysis shows there is notably less traffic (vehicle flow) and significantly fewer traffic jams (congestion) in West Dulwich when non catchment schools are on holiday. This reduces even more when state schools break up.

A tipping point

The reduction in traffic (or vehicle flow) is not as significant as the reduction in congestion. This means that although there are less cars, the reduction in traffic jams (congestion) is much more dramatic. This is because once there is a certain volume of traffic, a tipping point is reached, which means traffic will slow to a crawl.

 

The Dulwich school run is a collective, identifable body of cars that pushes the existing traffic levels over a tipping point to create congestion at peak times.

Croxted final 3.png

Data Source:TFL Scoot 

The good news...

This means it may only take a small reduction in car-use to significantly improve the congestion at peak hours in the area.   We are therefore really excited to start collaborating with schools, parents and councils to see if we can make that change. See Our Focus page for details.

School Run Journeys Estimation

How many journeys per day is the Dulwich & West Norwood school run?
We estimate around 11,000 daily car journeys during term time.

Here is how we worked it out: 

What % of pupils at each school type drive to school?

This depends on many factors but for estimate purposes we identified the following distinctions as key:

Catchment & non-catchment

If it is a catchment school, admissions are based on the distance pupils live from the school with priority given to the nearest.

If it is a non-catchment school there is no consideration given to where pupils live. The percentage of families driving will therefore be lower at catchment schools because pupils live nearer the school so can more easily walk, cycle or scoot.

Around 40% of pupils at schools in Dulwich & West Norwood attend non-catchment schools (9,000 of 22,000) so many of these 9,000 will not live within active travel distance from their school.

Primary & secondary

Secondary school children are older and more able to travel independently. Rates of driving at secondaries will be lower than primary schools for this reason.

Informed by data from HomeRun, an app that works with communities to reduce traffic around the school run, in addition to local data where known (from TFL STARS surveys), we came up with the following assumptions about the % of pupils who are driven to school by school type.

How many pupils in Dulwich & West Norwood parliamentary ward?

Pupil numbers here are 22,000 according to the 2021 census. 9,000 (40%) of these are at non-catchment schools. There is a very high density of non-catchment schools and therefore pupils in this area.

How many families is this?

We have adjusted the pupil numbers down by approximately 20% to get to the number of family units within schools. The average number of children/family in UK is 1.8, but not all siblings will be at the same school due to different ages, school selection processes, single sex schools etc so we have adjusted this down further as an estimate.

Of those pupils who are driven, how many car-pool?

We have assumed that 5% of pupils driven to school currently car-pool.

Workings

To get to our final estimate range we have done as follows:

% of pupils driven to school x 

number of families at the school x 

2.8 car journeys/day x 

95% to allow for car-pooling

= 8,400 to  12,700

journeys per day generated by school run trips in Dulwich & West Norwood.

11,000 is the mid point of this range.

 

Catchment primary 15-25%

Catchment secondary 5-10%

Non-catchment primary 35-45%

Non-catchment secondary 25-35%

What Does this Mean? 

11,000 car journeys per day is a huge number. That is 5,500 in the morning & 5,500 in the afternoon. For comparison, Croxted Road, a key boundary road in West Dulwich has vehicle flows of around 500 per hour between 8-9am. 

Additionally, our analysis shows that non-catchment schools make up about 55% (over 6,000) of the daily car trips but only 41% of the total pupils.

 

Increasing the sustainable travel options available to families at non catchment schools is therefore going to have the biggest impact on reducing traffic levels in West Dulwich.