The concept of charger catchment was introduced by Field Dynamics in our on-street household research (2020), with a comparable conceptual metric being the catchment area of a bus stop or a school (e.g. 1-2 miles).
The advantage of having a catchment based on time is that it will generate isochrones that vary according to the nature of the road network (or urban path network if you are walking). Catchments create polygons, and you can then count up what is inside each one.
An acceptable walk-time to a nearby charger from an on-street household was originally set at five minutes. As there was no ‘standard’ or ‘official’ metric at the time we sensibly invented one! This allowed us to derive statistics – e.g., 90% of non-London on-street households were not within a 5-minute walk of a public charger.
However, this value is already reducing and becoming ever more nuanced. Whilst drivetimes and walk times are useful and provide consistency, we often need to consider other factors.
Many local authorities now view 3 minutes as being the accepted time to walk to a public charger. Recent DfT research suggests 79% of current non-EV drivers walk less than two minutes to their ICE vehicle. However, it’s not just the time, there are also other considerations. Do drivers really want to walk three minutes at night, in the cold? There is also the layout of the road network to consider.
The significance of what is near is also becoming increasingly more nuanced. There are 3 categories:
- What is in the immediate vicinity? What else can I see?
- What is within a short drive? Maybe 5 or even 10 minutes? This covers those drivers who want to make a journey for both primary (I go to charge) and secondary (I do something else whilst I charge) purpose.
- What might be in a broader catchment – this will depend on what the type of location is – e.g., an attraction has a much larger catchment than your local supermarket for instance.
Real life example – CatchmentModeller tool used by over 80 Councils to help support Charger funding applications.
5 STEPS IN THE PROCESS
Decide the type of catchment you want – drivetime or walktime.
Decide the time you want to model travelling – time is the best option. Distance skews results – especially in busy urban areas
Decide what you want to count that is inside your catchment e.g. on-street households, fleet footprint, length and type of road, number of substations
Run this analysis across all your locations (you will need to consider an approach when catchments overlap each other)
Undertake variance analysis