Commuting to Work by Rail:Using Census Data for Spatial and Temporal Analysis

Presented at

Passenger Demand Forecasting Council Conference 2014Forecasting the Potential for Rail Growth

March 2014

Oliver Duke-Williams, UCLJohn Stillwell, University of Leeds

Outline• Context and definition• Census data products• Examples of analysis of mode of transport with

different census data sets• Access to the census data• Conclusions

Context and definition

Context• Significant supply and demand changes have taken place in labour

markets over last decade: e.g.– Suburbanisation and counterurbanisation (migration)– City living and working – urban renaissance– Feminisation and temporisation of workforce– Economic restructuring – tertiarisation,(e)retail– Home working

• Also key influences of the infrastructure side on travel mode demand with range of current related policy debates:– HS2 (phases 1 and 2)– Road building– Road pricing– Airport expansion– Environmental concerns

• Changes such as these have an impact of the locations of homes and jobs and therefore will be accompanied by changes in commuting behaviour (including mode of travel) and therefore on spatial and temporal commuting patterns

• Dictionary definition (Oxford Dictionary, 2012):

• “a person who travels some distance to work on a regular basis”

• Main Census questions (2001 and 2011)– England, Wales and Northern Ireland:

• “In your main job, what is the address of your workplace?”• “How do you usually travel to work?”

– Scotland:• “What address do you travel to for your main job or course

of study (including school)?”• “How do you usually travel to your main place of work or

study (including school)?”

Commuting Definition and Census Questions

• Census commuting data only captures individuals in formal employment

• Census fails to capture people not in formal employment, such as carers

• What is the appropriate denominator for commuting rate?– Total population– Population aged 16+– Population aged 16-74 or 16-64– Economically active population– Employed population

Commuting Definitional Issues

2001 data products

Six main census datasets in 2001:

– Aggregate statistics– Interaction data (SWS and STS)– Microdata (SARs, SAM and CAMS)– Longitudinal studies– Commissioned tables– Geographical boundaries

2001 Aggregate Statistics: Mode of transport• Published as tables in Key Statistics (KS), Standard Tables (ST)

and Census Area Statistics (CAS) at different geographical levels

• KS015: Travel to work data

• CS119/ST119: Sex and age by mode of transport • CS121/ST121: Sex and distance travelled to work by mode of

transport • CS122/ST122: Sex and socioeconomic group by mode of transport• ST129: Sex and distance travelled to work by mode of transport

(workplace population)• ST tables have more detailed breakdowns that CS tables

2001 Interaction Data • Special Workplace Statistics (SWS) in England, Wales and NI• Special Travel Statistics (STS) in Scotland• Geographical units used in 2001 SWS/STS:

Country Level 1 Level 2 Level 3

England London Boroughs (33), Metropolitan Districts (36), Unitary Authorities (46), Other LAs (239)

CAS wards (7,969) Output areas (165,665)

Wales Unitary Authorities (22) CAS wards ( 881) Output areas (9,769)

Scotland Council Areas (32) ST wards ( 1,176) Output areas (42,604)

NorthernIreland

Parliamentary Constituencies (18)

CAS wards (582 ) Output areas (5,022)

Total Districts (426) Interaction wards (10,608)

Output areas (223,060)

SWS Mode of transport tables

Major problem with 2001 data:Small cell adjustment (SCAM)

• Large proportion of SWS flows are small, particularly at OA level• This poses potential disclosure risks• In 2001, ONS decided to adjust all flows of 1 and 2 to either 0 or 3

(Scotland chose not to follow suit so STS have not been SCAMmed)• SCAM applied post-tabulation – so numbers in each table (e.g.

mode of travel at levels 1, 2, 3 may not sum to the same total)• Has had a major impact on the flow data at OA level

2001 Census Microdata

• Samples of Anonymised Records (SARs)Individual SAR – 1% sample (around 500,000 individuals)Household SAR – 1% sample

• Small Area Microdata (SAM)5% sample (around 3 million individuals)

• Controlled Access Microdata Samples (CAMS)Available from safe setting

Census Longitudinal Data: LS in England and Wales

Source: CeLSIUS web site at http://ucl.ac.uk/celsius

2011 Census data products:Commuting flow data

Commuting data products have evolved

1981

1991

2001

2011

Special Workplace Statistics

SWS

SWS

SWS STSSpecial

Residence Statistics

(SRS)

Special Travel

Statistics

2011 Special Residence Statistics (SRS)• Based on new questions on second residences• Only asked in England and Wales

• Possibly able to analyse the relationships between the use and locations of second addresses for work purposes and commuting behaviour/patterns

2011 Origin-Destination outputs• Level of attribute detail

– Flow tables: headcounts only– Univariate tables: flows disaggregated by a single variable– Multivariate tables: disaggregated by two or more

variables • Levels of security classification

– Open• Open Government Licence (OGL), freely usable

– Safeguarded• Perhaps via some sort of End User Licence (EoL)?

– Secure• Approved Researcher accreditation via Virtual Microdata Lab

(VML)?• New geography of destinations: Workplace Zones

(WPZs)• Phased releases commencing in June(?), 2014

‘Possible’ security classifications for 2011 SWS

Geography SWS Flows/Headcounts

SWS Univariate

SWS Multivariate

LA to LA Public Sex, Age, Method of travel: PublicOthers: safeguarded

Sex by Age: PublicSome variables: safeguardedOther variables:Secure

MSOA to MSOA Public Sex, Age, Method of travel: PublicOthers: Safeguarded

Sex by Age: PublicSome variables: safeguardedOther variables:Secure

OA to OAOA to WPZ

Safeguarded All: Secure All: Secure

• Adapted from outline in document circulated at ONS Census Origin Destination and Microdata Working Group meeting in November 2013• Based on specifications compiled for ONS by Oliver Duke-Williams • All provisional

Examples of analysis of mode of travel using different census products

Most used methods of travel to work in London by OA, 2001

Source: Aggregate statistics from 2001 Census

Rail and Underground commuting rates to four wards of central London by ward, 2001

Rail

Underground

Data sources: 2001 and 2011 Census data (Tables KS015 and CT0015) via UK Data Service

England and Wales Commuting Overview : Numbers and Rates English Government Office Region (GOR)

2011 No. of Commuters

% Change 2001-11

2001 Commuting Rate* (%)

2011 Commuting Rate* (%)

% Point Change 2001-11

England and Wales 26,526,336 +12.3 62.8 64.5 +1.7

England 25,162,721 +12.1 63.2 64.7 +1.5

Wales 1,363,615 +15.0 57.2 60.7 +3.5

North East 1,152,970 +11.6 56.4 59.9 +3.5

North West 3,228,744 +11.3 59.9 62.3 +2.4

Yorkshire and The Humber 2,428,074 +11.2 61.1 62.7 +1.6

East Midlands 2,146,541 +11.9 63.5 64.3 +0.8

West Midlands 2,536,876 +8.7 61.7 62.4 +0.7

East 2,849,512 +10.5 66.4 67.1 +0.7

South East 4,260,723 +9.6 67.4 67.9 +0.5

South West 2,560,384 +12.0 64.7 66.4 +1.7

London 3,998,897 +20.5 62.6 65.4 +2.8

*Number of commuters as a percentage of population aged 16-74

Main changes:• 16% increase in the share of employees working mainly at or from home• 22% increase in the share of employees commuting to work by train• 3% decrease in the share of employees commuting to work by bus• 2% decrease in the share of employees commuting to work by driving a car• 21% decrease in the share of employees commuting to work as a car passenger

Data sources: 2001 and 2011 Census data (Tables KS015 and CT0015) via UK Data Service

Modal Split in England and Wales, 2001 and 2011

0

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20

30

40

50

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Commuting Mode of Transport

2001

2011

ÜEast

NorthEast

NorthWest

Yorkshire andThe Humber

WalesWest

Midlands

EastMidlands

South West South East

London

Commuting to Work by Train in England and Wales, 2001 and 2011

Commuters in LAD who commute to work by train as a % of all commuters in LAD aged 16-74

2001 2011

Data sources: 2001 and 2011 Census data (Tables KS015 and CT0015) via UK Data Service

NorthEast

London

East

South EastSouth West

WalesWest

Midlands

EastMidlands

Yorkshire andThe Humber

NorthWest

LegendGORs

Train Commuting by District% of commuters aged 16-75

< 1%

1% - 3%

3% - 5%

5% - 7%

> 7%

0 25 50 75 10012.5Miles

• New questions in 2011 Census– England and Wales:

• “Do you stay at another address for more than 30 days a year?”• “What is that address?”

– “Armed forces base address”– “Another address when working away from home”– “Student’s home address”– “Student’s term time address”– “Another parent or guardian’s address”– “Holiday home”– “Other”

• Possibly able to analyse the relationships between the use and locations of second addresses for work purposes and commuting behaviour/patterns

Second Addresses for Work Purposes

ÜLegend

GORs

Second address Locations by District% of usual residents

< 0.2%

0.2% - 0.5%

0.5% - 1%

1% - 2%

> 2%

East

London

NorthEast

NorthWest

Yorkshire andThe Humber

EastMidlands

WestMidlandsWales

South WestSouth East

CentralLondon

Usage and Locations of Second Addresses for Work in England and Wales, 2011

Residents of LAD who use a second address elsewhere for work as a percentage of LAD population

Residents of elsewhere who use a second address in LAD for work as a percentage of LAD populationData Sources: 2011 Census data via UK Data Service

LegendGORs

Second Address Usage by District% of usual residents

< 0.2%

0.2% - 0.4%

0.4% - 0.6%

0.6% - 0.8%

> 0.8%

East

London

NorthEast

NorthWest

Yorkshire andThe Humber

EastMidlands

WestMidlandsWales

South WestSouth East

CentralLondon

Percentages and changes in long commutes (5km cut-point) by mode of transport in England and Wales aged 16-74 between 1991 and 2001

Long Commute (1991)

Long Commute

(2001)

Change (1991-2001)

Mode of transport

Train, Underground and Tram

87.9 88.3 0.4

Bus 42.7 43.8 1.1Car (Driver) 56.7 64.1 7.4Car (Passenger) 44.3 48.1 3.9Bicycle 17.2 22.2 5.0On Foot 5.0 9.4 4.4Homeworker 0.1 0.0 -0.1Other 49.8 55.7 5.9

Sources: 1991 and 2001 SARs)

Longitudinal data: Do people maintain the same method of travel to work over the course of a decade, 1991-2001?

Mode of transport to work 1991

Mode of transport to work 2001 0.

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1. Works at/from home 2,860 253 461 581 118 8,053 585 267 926 14,1042.Tube/Metro/Light rail 37 918 258 272 15 458 76 33 156 2,2233. Train 66 422 1,922 337 27 1,293 185 86 278 4,6164. Bus/Minibus/Coach 105 194 261 2,902 78 1,083 717 170 1,129 6,639

5. Motor cycle etc 29 28 50 60 373 644 70 104 104 1,462

6. Drive car/van 2,086 767 1,755 4,059 1,200 61,597 4,851 1,788 5,310 83,4137. Passenger car/van 147 52 140 1,098 88 1,903 1,859 218 1,041 6,5468. Taxi/Minicab 16 13 20 85 11 213 83 11 72 5249. Bicycle 67 47 64 231 131 1,052 182 1,231 477 3,48210. On foot 429 111 190 1,109 114 2,420 871 409 4,798 10,45111. Other 476

Total 5,842 2,805 5,121 10,734 2,155 78,716 9,479 4,317 14,291 534 133,994

Sources: 1991 and 2001 Census LSs for England and Wales

Mode of transport to work 1991

Mode of transport to work 2001 0.

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1. At home 2,860 253 461 581 118 8,053 585 267 926 14,104Column% 49.0% 9.0% 9.0% 5.4% 5.5% 10.2% 6.2% 6.2% 6.5% 10.5%

2. Tube etc 37 918 258 272 15 458 76 33 156 2,223Column% 0.6% 32.7% 5.0% 2.5% 0.7% 0.6% 0.8% 0.8% 1.1% 1.7%

3. Train 66 422 1,922 337 27 1,293 185 86 278 4,616Column% 1.1% 15.0% 37.5% 3.1% 1.3% 1.6% 2.0% 2.0% 1.9% 3.4%

4. Bus 105 194 261 2,902 78 1,083 717 170 1,129 6,639Column% 1.8% 6.9% 5.1% 27.0% 3.6% 1.4% 7.6% 3.9% 7.9% 5.0%

5. Motor cycle 29 28 50 60 373 644 70 104 104 1,462Column% 0.5% 1.0% 1.0% 0.6% 17.3% 0.8% 0.7% 2.4% 0.7% 1.1%

6. Drive car/van 2,086 767 1,755 4,059 1,200 61,597 4,851 1,788 5,310 83,413Column% 35.7% 27.3% 34.3% 37.8% 55.7% 78.3% 51.2% 41.4% 37.2% 62.3%

7. Passenger 147 52 140 1,098 88 1,903 1,859 218 1,041 6,546Column% 2.5% 1.9% 2.7% 10.2% 4.1% 2.4% 19.6% 5.0% 7.3% 4.9%

8. Taxi/Minicab 16 13 20 85 11 213 83 11 72 524Column% 0.3% 0.5% 0.4% 0.8% 0.5% 0.3% 0.9% 0.3% 0.5% 0.4%

9. Bicycle 67 47 64 231 131 1,052 182 1,231 477 3,482Column% 1.1% 1.7% 1.2% 2.2% 6.1% 1.3% 1.9% 28.5% 3.3% 2.6%

10. On foot 429 111 190 1,109 114 2,420 871 409 4,798 10,451Column% 7.3% 4.0% 3.7% 10.3% 5.3% 3.1% 9.2% 9.5% 33.6% 7.8%

11. Other 476

Total 5,842 2,805 5,121 10,734 2,155 78,716 9,479 4,317 14,291 534 133,994

Sources: 1991 and 2001 Census LSs for England and Wales

Online Access to Census Data

UK Data Service http://ukdataservice.ac.uk/

UK Data Service - Census Support

Conclusions• Census provides plenty of commuting data at variety of spatial scales

– reliable, comprehensive coverage, small area geography • But there are shortcomings – definitional, infrequency, adjustment

methods, temporal inconsistency, ...• Official structure and availability (timing and licensing) of 2011 origin-

destination commuting data still awaited• Decision on ‘census alternatives’ (‘Beyond 2011’ programme) due in

September 2014 – no current plans to collect any interaction data sets if the traditional census is dropped

• Results of the 2011 Census important for analysis at small area scale because they could well be the last set of UK-based commuting flow data that ONS collects

Contact details

Oliver Duke-WilliamsDepartment of Information Studies

UCLLondon WC1E 6BT

Email: o.duke-williams@ucl.ac.uk