A public consultation on the future design of the National Travel
Foreword from the Head of Statistics 2
Executive Summary 3
How to respond 4
Freedom of Information 4
The Consultation Criteria 5
What will happen next 5
The proposals 6
Consultation questions 28
Question and Answer Brief 30
A - List of those consulted 35
B - List of Consultation Criteria 37
Foreword from the Head of Statistics
This consultation about the future of the National Travel Survey is an important step forward with regard to the measurement of both how and why people travel. It demonstrates the commitment of statisticians within the Department for Transport to continue to produce high-quality statistics in the public interest and which meet the needs of users. I welcome the innovative use of technology outlined in the consultation which could improve the statistical data from the survey. The consultation also explicitly explores options to reduce costs. It is important for us to understand how these proposed changes in the survey scope and design would affect users, and the Department for Transport would welcome responses to our proposals.
Head of Profession for Statistics
Department for Transport
The National Travel Survey (NTS) is one of the Department for Transport’s (DfT’s) most essential and fundamental evidence sources. It has been run continuously since 1988. It is the primary source of data on the personal travel patterns of British households and as such it is used extensively both within DfT and across the wider transport sector.
The current contract for the NTS covers fieldwork to the end of 2012. We will therefore need to put new arrangements in place for data collection in 2013 and beyond. This consultation is being carried out to inform the detail of these arrangements. It aims to ensure that, while delivering the department’s objectives in relation to the NTS, we take full account of the needs and interests of the wider NTS user community.
DfT statisticians are always seeking to develop and innovate in order to get the greatest possible value from the NTS. In recent years, our development work has been focused on the potential use of personal Global Positioning System (GPS) devices to collect the personal travel data that is currently collected via a written travel diary. GPS devices offer major potential advantages, but also present a number of challenges and risks. These are discussed in section 1, which seeks
users’ views on whether the future design of the NTS, from 2013 onwards, should be
based on the use of GPS devices instead of the written travel diary.
In parallel with this consultation, we are undertaking a full pilot of the use of GPS devices within the current NTS. The pilot’s fieldwork ended in May 2011 but the full
pilot findings will not be available until autumn 2011, after this consultation has closed. We will therefore base our decision (on whether or not we adopt GPS data collection in the design of the NTS) on both the findings from the pilot and from responses to this consultation.
While exploring potential innovation, it is also critically important that the department collects the data delivered by the NTS as cost-effectively as possible. We are therefore explicitly seeking to reduce the cost of NTS data collection to the department and are putting forward a number of proposals with this objective in mind. We are seeking users’ views on which could most sensibly be pursued. The
; Removing groups of relatively lower-value questions from the NTS
questionnaires in order to reduce the average interview duration (section 2);
; Reducing the geographic coverage of DfT-funded survey fieldwork from Great
Britain to England, reflecting the devolution of many areas of transport policy
in Scotland and Wales (section 3);
; Other, wider potential changes to aspects of the data collection (section 4).
This consultation is directed at NTS users and stakeholders. When providing feedback on the four areas of proposals, those responding are encouraged to focus upon the key questions set out in section 5. These include whether respondents
support the proposals, and how the proposals (or features of them) would affect their work either positively or negatively. There is also a more open invitation to suggest changes to the data items collected or the data collection methods used that this consultation may not have explicitly considered. Section 6 contains Q&A briefing on
issues relating to the proposals put forward for consultation.
How to Respond
The consultation period began on 9 June 2011 and will run until 5 September 2011, please ensure that your response reaches us by that date. If you would like further copies of this consultation document it has also been published on the Department’s
website and can be found at http://www.dft.gov.uk/consultations or you can contact
us using the contact details below, if you would like alternative formats (Braille, audio CD, etc).
Please send consultation responses to
National Travel Survey Consultation
The Department for Transport
2/13 Great Minster House
76 Marsham Street
Tel: 020 7944 3097
Fax: 020 7944 2166
If you would prefer to respond to the consultation online, it is possible to do so at Citizen Space at https://consultation.dft.gov.uk.
When responding, please state whether you are responding as an individual or representing the views of an organisation. If responding on behalf of a larger organisation please make it clear who the organisation represents, and where applicable, how the views of members were assembled.
DfT has scheduled a stakeholder meeting to discuss this consultation at 10.00 on 14 July 2011. This will be held at the Royal Statistical Society 12 Errol Street, London, EC1Y 8LX. If you would be interested in attending this event, please use the above contact details to register your interest.
A list of those consulted is attached at Annex A. If you have any suggestions of others who may wish to be involved in this process please contact us.
We would like to thank those who respond to our consultation in advance. We do not intend to acknowledge individual responses unless by request.
Freedom of Information
Information provided in response to this consultation, including personal information, may be subject to publication or disclosure in accordance with the Freedom of Information Act 2000 (FOIA) or the Environmental Information Regulations 2004.
If you want information that you provide to be treated as confidential, please be aware that, under the FOIA, there is a statutory Code of Practice with which public authorities must comply and which deals, amongst other things, with obligations of confidence.
In view of this it would be helpful if you could explain to us why you regard the information you have provided as confidential. If we receive a request for disclosure of the information we will take full account of your explanation, but we cannot give an assurance that confidentiality can be maintained in all circumstances. An automatic confidentiality disclaimer generated by your IT system will not, of itself, be regarded as binding on the Department.
The Department will process your personal data in accordance with the Data Protection Act (DPA) and in the majority of circumstances this will mean that your personal data will not be disclosed to third parties.
The Consultation criteria
The consultation is being conducted in line with the Government's Code or Practice on Consultation. The criteria are listed at Annex B; a full version of the Code of Practice on Consultation is available on the Better Regulation Executive web-site at:
There is no accompanying Regulatory Impact Assessment for this consultation as the National Travel Survey is non-Regulatory.
If you consider that this consultation does not comply with the criteria or have comments about the consultation process please contact:
Department for Transport
Great Minster House
London SW1P 4DR
Email address firstname.lastname@example.org
What will happen next?
A summary of responses, including the next steps will be published by 31 October 2011 on the DfT web site; paper copies will be available on request.
The National Travel Survey (NTS) is one of the Department for Transport’s (DfT’s) most essential and fundamental evidence sources. It has been run continuously since 1988. It is our primary source of data on:
; overall levels of personal travel in Britain, across all transport modes;
; how and why people travel;
; how travel patterns change over time, and
; how travel patterns vary by individual and household circumstances.
The department’s uses of NTS data are wide and varied. Alongside a great many ad-hoc and issue-specific uses, our more significant and ongoing uses of the data include:
; calibrating and maintaining the National Transport Model and the associated
National Trip End Model dataset and WebTAG. These are standard tools used
by transport planners in developing and appraising business cases;
; monitoring one of the eight impact indicators in the DfT Business Plan 2011-
; evaluating the potential distributional impact of transport policies (through
quantitative data on the travel patterns of different social and economic
; estimating the total number of road accidents in Great Britain, including those
accidents that are not reported to the police.
The department has a clear and continuing need for the data that the NTS provides. We require data on personal travel behaviour that, as far as reasonably possible:
; is accurate and robust to the standard required of an official statistic;
; covers all domestic transport modes;
; covers all sectors of the resident household population;
; is comparable over time, and
; allows analysis of travel behaviour according to personal circumstances (e.g.
age, income, employment status, car ownership, etc.)
However, in addition to its applications within DfT, the NTS also has a very wide range of external users. An annual statistical release, with accompanying topic reports and statistical tables, is published by DfT as a National Statistic and is widely used. The DfT also makes an anonymised version of the NTS data set available to researchers, and answers many ad-hoc requests from external enquirers for NTS data and statistics.
All NTS fieldwork is currently contracted out to the National Centre for Social Research (NatCen), a not-for-profit social research institution. This contract expires upon completion of fieldwork for the 2012 survey year. We will therefore need to put new arrangements in place for data collection in 2013 and beyond. This consultation is being carried out to inform the detail of these arrangements. It aims to ensure that, while delivering the department’s objectives in relation to NTS data, we take full account of the needs and interests of the wider NTS user community.
1. Replacing the travel diary with personal GPS devices
11.1 The NTS currently uses a seven-day travel diary to collect personal travel data.
This is a structured paper booklet completed by hand by individual survey participants, beginning on a pre-determined date after the main survey interview has been conducted. On completion, it is collected by the original interviewer who conducts a brief ‘pick up’ interview. The diary has been in place since the NTS was
created and, for most of the survey’s lifetime, it has been the only feasible method of collecting data on actual journeys made. However, it has several key weaknesses, including:
; the instructions for completion are complex and subject to misinterpretation;
; it yields data that is sensitive to minor changes in diary design, whose
effects can be difficult to predict;
; it is lengthy and places a heavy burden on respondents;
; it is very difficult to collect data from people with literacy problems or limited
English language knowledge;
; some journeys have to be excluded for reasons of basic practicality (e.g.
business journeys of delivery drivers and people in similar jobs);
; the complexity of the diaries, and the ‘free text’ nature of some of the data
fields, means that it is not feasible to process them automatically. They
therefore require manual coding and data entry, which is a significant
ongoing cost, and
; it is heavily reliant on complete and accurate respondent recall, meaning
that there is a potential (but unknown) ‘human error’ affecting the quality of
all data collected.
1.2 In 2006, the Department commissioned and published a review of the scope for 2using technology to improve the quality and reliability of NTS diary data. Personal
GPS devices were considered the most suitable option to deliver affordable and practical improvement. In January 2010, DfT published the findings of a feasibility study, undertaken during 2008 and 2009, which explored the scope for using 3personal GPS devices in the NTS. This confirmed that GPS technology has real
promise for use within the NTS and did not uncover any fundamental barriers of feasibility or public acceptability.
1.3 A key reason for its acceptability is that the British public is becoming increasingly familiar with GPS technology. GPS chips are a core component of ‘SatNav’ devices and many higher-specification mobile phones. The continued use of a paper diary to collect travel data therefore risks appearing increasingly antiquated
1 Adult travel diary:
Children’s travel diary:
http://www.dft.gov.uk/pgr/statistics/datatablespublications/nts/technical/youngtrcrd.pdf 2 Review of the Potential Role of 'New Technologies' in the National Travel Survey
http://webarchive.nationalarchives.gov.uk/+/http://www.dft.gov.uk/pgr/statistics/datatablespublications/personal/methodology/ntsreports/ntsreviewtechnologies.pdf 3 National Travel Survey GPS Feasibility Study
and potentially off-putting to the growing proportion of survey respondents who are comfortable and confident users of technology.
1.4 The UK is not the only country that has been exploring the potential use of GPS technology in personal or household travel surveys. Pilot studies have already been undertaken by Israel, France and the Netherlands, and in several US states and cities. There have also been a number of smaller-scale projects and studies in the academic sector. We have kept in touch with the work of international and academic colleagues in planning and designing our own fuller and more detailed pilot of the use of GPS devices in the British NTS, building on the positive initial findings of the feasibility study.
1.5 The GPS ‘option’ proposed in this document would constitute a permanent switch from solely using travel diaries to collect personal travel data, to solely using GPS devices. While there may be scope to undertake dual running of the two data collection methods over a transitional period, this would be a time limited exercise, after which data collection would be collected solely using GPS devices.
The NTS GPS pilot survey
1.6 Following a brief review of the GPS devices available on the market, carried out in order to ensure that we were fully exploiting the available technology, a full GPS pilot project commenced in September 2010. Data collection is being carried out by the current NTS contractor (NatCen), using existing NTS interviewers and following established NTS methodology wherever sensible and feasible.
1.7 A key feature in the design of the pilot was that the GPS devices used had to be as ‘passive’ as possible (i.e. requiring no user input other than overnight charging of the device battery). This was considered essential in order to eliminate the ‘human error’ component as far as possible, and thereby ensure that data from all devices could be processed in a standardised and automated fashion.
1.8 The pilot used personal GPS devices that are equipped with three accelerometers (arranged in three dimensions, one for each of the X, Y and Z axes). These measure change in acceleration on each axis, effectively acting as ‘vibration
sensors’ and recording the pattern of vibration generated as the device holder moves around by various means. The accelerometer data is potentially extremely useful in deriving mode of travel for a particular journey stage, as different modes of transport generate distinctly different patterns of vibration (see below) in the accelerometer data streams.
1.9 The pilot also used an adapted version of the standard NTS interview questionnaire, Information on frequently-visited addresses was collected for each respondent, so that this could be used in conjunction with the recorded GPS data to derive the purpose of a particular journey. (For example, a trip from a respondent’s home to their reported usual place of work is highly likely to be for the purpose of commuting.)
1.10 The pilot has been designed to deliver a target sample of interviews with approximately 800 individuals in 450 households, along with GPS data for all participating individuals aged 12 and over. Fieldwork commenced in February 2011, and was completed in May 2011, at which point the GPS ‘traces’ and supporting
interview data were transferred to the University of Technology in Eindhoven (TU/e) in the Netherlands for processing. It is anticipated that anonymised, processed trip and stage data will be returned to the DfT in September 2011.
1.11 DfT will then undertake summary analysis of the GPS data, comparing GPS outputs to the un-weighted results for the main NTS travel diary data for the same period. Outputs will include a summary report of the analysis, and technical reports from NatCen and TU/e on the data collection and processing. These outputs will be used, alongside the responses to this public consultation, to support DfT’s decision-
making on the future data collection methodology to be used in the NTS beyond 2012.
1.12 As the NTS GPS pilot is still ongoing, with the data analysis and processing stages still to be completed, it is not possible to give a final assessment of the benefits and risks of switching to GPS data collection in the NTS. The remainder of this section therefore represents our best understanding at the time of writing (May 2011), but this may change in the light of the full pilot findings.
The potential benefits of a GPS methodology
1.13 Using accelerometer equipped GPS devices instead of paper travel diaries would significantly reduce the burden on respondents. GPS would be easy to use and unlike the diary does not pose a problem for certain groups such as those with sight impairments, literacy problems or poor knowledge of the English language.
1.14 Given a stable signal, the data collected by GPS devices would be more accurate than that collected by diaries: providing actual length of journey (distance and time) rather than estimates, precise start and end points, data for all walking trips (rather than short walks on day seven only) and data from which we could also derive speed of travel and acceleration.
1.15 GPS devices can also be used to collect a range of new data items which, for practical reasons, could not be obtained via a written diary. This includes data on all travel activities, including walking, running and cycling trips regardless of distance, and travel ‘off network’ (e.g. in parks or on open land). This would provide a much
richer dataset for estimating total ‘active travel’. We would also have collected
detailed information on:
; actual routes taken (not simply origin / destination) at very detailed street-
by-street or stop-by-stop level;
; how long respondents spend waiting for public transport.
; business travel by delivery drivers, etc.
; average speeds.
1.16 GPS route ‘trace’ data would enable new and innovative approaches to the
analysis of personal travel patterns. For example, it would be possible to make meaningful use of Geographic Information System (GIS) software for the first time. Linkage between GPS ‘traces’ and industry-standard mapping data could provide
new insight on the proportion of car trips / travel time / distance travelled by the type of road travelled upon (A road, B road, motorway). In addition, all of the above data could be analysed according to standard survey demographic variables (age, gender, income, household composition, etc.). There would therefore be very considerable scope for generating new insight and intelligence about personal travel behaviour,
with potential benefits for DfT, the wider public sector, academia, and private businesses. We would aim to release as much GPS-derived data as reasonably possible for use outside DfT, while fully meeting our obligation to protect the privacy of survey participants.
1.17 Some savings may be achieved by replacing the printing and manual coding of some 22,000 travel diaries with automated GPS collection. Manual coding in particular is time-consuming and represents a significant ongoing cost in the current NTS design. The exact scope for savings is not yet clear, and they would obviously be offset by initial purchase cost of the GPS devices, and the need to maintain them and replace lost or broken units as fieldwork progresses. However, it is feasible that a net saving could be achieved over the course of a multi-year contract by switching from diaries to GPS.