Nearly 30% of heavy commercial vehicles transiting Bath pass through Bathampton (on the A36).

We looked in earlier blogs at the overall patterns of traffic transiting Bath, using council and BathHacked data. 

In this blog we drill into the detail by type of vehicle, essentially car, and light- or heavy-commercial vehicle. We show that more transiting heavy commercial vehicles go through Bathampton on the A36 than use the Batheaston dual-carriageway.

For variety, and to show it's not very sensitive to the time threshold, in this blog we use a 45 minute threshold, and a 2-day sample (31 October and 1 November 2017). The chord diagram, which is aligned roughly geographically, looks like this.

Splitting each chord by type of vehicle, and colouring them not by starting point, but by type of vehicle gives this. Although it shows that cars are by far the biggest number of vehicles, it's hard from this to see if there are differences in the patterns.

A diagram for each could be confusing because the scales are now different: total in and out at Bathampton (Dry Arch) is near 2,000 for cars, 700 for light, and 450 for heavy commercial vehicles. 

Cars and light commercial vehicles have quite similar patterns: for light commercials there's perhaps a little higher proportion on the Swainswick-East link. But heavy commercials are very different:

• a much higher proportion are really crossing town: Bathampton - West;
• there's a much smaller proportion of traffic South-South, or South-West.

As a result, Bathampton has more than twice the share of heavy commercial transits than its share of total transits. 12.5% of all transits (3003/23841 in our sample go in or out at Bathampton (Dry Arch), compared to 28.5% (318/1116) of heavy commercials.

In fact, more transiting heavy commercial vehicles go through Bathampton on the A36 than use the Batheaston dual-carriageway.