Exploiting census workplace data to build a daytime grid map of England and Wales. David Martin, Samantha Cockings, Alan Smith European Forum for Geostatistics, 10 November 2015

Overview Usual residence New census workplace zones and data for 2011 Space-time population modelling 2011 England and Wales time-specific grids Conclusion 2

Usual residence Conventional census and register population base is usual residence By extension, census geography is itself a geography of usual residence England and Wales census output areas 2001, 2011 designed to maximise data utility in context of residential address locations (threshold size, target size, geographical shape) – mean population 309 Most census counts are therefore representations of the characteristics of the night-time population Workplace questions asked but limited output data in 2001 census Working population has an entirely different spatial distribution to residences 3

4 Photos: David Martin

New census workplace zones and data for 2011 New workplace zones (mean 493 workers) for publication of census statistics relating to the working population at place of work –Some output areas have large workplace populations and can be subdivided into smaller workplace zones – Some output areas can also be workplace zones –Some output areas have small (or zero) workplace populations and need to be combined with others to create a larger workplace zone Implemented using automated zone design procedures very similar to those used for output areas Control over size allows much more workplace data to be published: 25 tables at workplace zone level 5

6 Contains National Statistics and Ordnance Survey Data © Crown copyright and database right 2014 Output areas Workplace zones Unit postcodes

Why worry about non-residential population? It’s a a major component of overall population distribution, especially during day-time Variation over seasons, term times, day of week, time of day and other cycles Understanding time-specific population patterns is of particular relevance where population “exposure” is concerned: e.g. delivery of daytime services, transport planning or emergency planning Widespread interest in day-time, ambient, real-time populations for relevant applications Day-time population distribution also reflects education, health, leisure, transportation and many other activities 7

Night-time model: residential only, conventional grid 8 Residential origin locations e.g. addresses, postcodes, OAs Daytime destination locations e.g. workplaces, schools, hospitals

Day-time model: mixed activities – but which ones? 9 Residential origin locations e.g. addresses, postcodes, OAs Daytime destination locations e.g. workplaces, schools, hospitals

Wednesday morning, school holiday… many grids? 10 Residential origin locations e.g. addresses, postcodes, OAs Daytime destination locations e.g. workplaces, schools, hospitals

Space-time population modelling Population 24/7 project, implemented time-based version of SurfaceBuilder software – original work limited by lack of Open Data and census workplace data Time-specific grids built from library of population centroids, with time profiles –Origins, defining all locations of residential population (output areas) –Destinations, which may contain non-residential populations at specified times (workplaces, schools, etc.) Background layer (road network, water bodies) defines weighting mask Each centroid examined in relation to target time; population redistributed into grid cells according to relevant point in centroid time profile 11

Sources of centroids and time profiles Census population totals by (residential) output areas and workplace zones Non-census destinations populations from Open Data sources on schools, colleges, universities, hospitals and visitor attractions Ordnance Survey OpenData for road network, background mapping Department for Transport Open Data on average annual daily road traffic flows Quarterly Labour Force Survey for working patterns by industry class Administrative and survey data sources on school opening hours, hospital appointment times – many possible extensions 12

13 Acronyms: UoS = University of Southampton, HES = Hospital Episode Statistics, DfT = Department for Transport, NTM = National Transport Model, OS = Ordnance Survey Total population +/- external visitors Private dwellings Non- residential Communal ests. Transport Employment Education Residential Temp accomm. Generalised local Family/social Retail Leisure Tourism Healthcare Rail Metro/subway Air Water RoadLocations Data Sources census area statistics census area statistics (workplace pop) - EduBase (school census), UoS travel survey Visit England - Health and Social Care Information Centre, HES DfT NTMStatistics, OS Meridian OpenData -

2011 England and Wales time-specific grids Demonstrating the feasibility of integrating Open datasets to generate time- specific population models over a large area at 2011 census reference date Census output area centroids as population origin locations, define total population to be modelled Workplace zone centroids for workplace populations, by industry classification School, college, university, hospital, and visitor attractions as destination locations by postcode – treated as additional destination centroids Every destination centroid associated with a standard time profile England and Wales, weekday 02:00 and 14:00 target times, 200 x200m grid 16

2011 term-time weekday 02:00 Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 14:00 Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 02:00 Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 14:00 Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 14+02:00/2 Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 02: Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

2011 term-time weekday 14: Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2015; Copyright © 2015, Re-used with the permission of the Health and Social Care Information Centre. All rights reserved. Contains public sector information licensed under the Open Government Licence v3; © OpenStreetMap contributors

Conclusion 2011 England and Wales workplace zone dataset provides a major component necessary for day-time population grid modelling Other Open Data sources providing increasingly useful evidence for other day- time activities and also for time profiles Different demographic sub-groups display different time-specific geographical distributions We should be developing and using time-specific population grids that are most appropriate to the intended application 24