search

cyipt / actdev

ActDev - Active travel provision and potential in planned and proposed development sites
https://actdev.cyipt.bike
7 stars 3 forks source link

Baseline mode-split data changed - how come? #154

Closed Siequnu closed 3 years ago

Siequnu commented 3 years ago

I re-ran the Python script mentioned here to re-generate the aggregate mode-split data for sites. The .csv file data this script generates are displayed on the national-level bar chart.

For context, this was previously run sometime near end of February.

I noticed that, in the base-line (current) scenario, the number of commuters in the sites seems to have changed. In the case of Allerton-Bywater, the base mode-split numbers changed from (walk_base,cycle_base,drive_base,other_base) 23, 7, 389, 120 to 22, 6, 396,129. So the site went from having 539 commuters to 553. Similar changes happened to the other sites.

The report gives the following formula for the calculation of the baseline stats Baseline trips = 2011 Census trips from local MSOA(s) / 2011 MSOA population(s) * Number of dwellings at completion * Mean household size — I'm curious as to which of these variables might have changed?

joeytalbot commented 3 years ago

This is probably related to the disaggregation of desire lines. We switched to using disaggregated desire lines for the mode split in both the baseline and go active scenarios, for any site that has <20 desire lines within the study area.

Robinlovelace commented 3 years ago

I think we can close this now. Any objections @Siequnu or @joeytalbot ? It's including a different subset of desire lines I think.

Siequnu commented 3 years ago

Good to get insight into the methodology.