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Paper 16th September 2003 - TTSAC(03)6


1. This paper seeks the views of Members of the Committee on possible needs for statistics, other than those that have been covered under earlier agenda items. It follows the previous meeting's proposal to produce a paper on the needs for statistics, and the request that the need for origin and destination data be on the agenda for this meeting.

2. Last year, the then Chairman asked Members of the Committee to send him their views on the kinds of information and analysis that were required. Two Members did so. Points from their e-mails have been summarised below, as a possible starting point for discussion (comments on matters covered by earlier papers, such as measures of congestion and journey time reliability, have been omitted). Some Scottish Executive notes have been added - these appear in italics.

3. General comments

  • traditional data sources (e.g. traffic flows) help providers to manage operational aspects of transport - require new data sources viewing transport systems from user's perspective;
  • regardless of how much analysis you do on the SHS and related data, users will want something else - SE should not try to "second-guess" what users might want.

4. Origin and destination data

  • required to understand how travel behaviour is changing;
  • SHS travel diary very important data source;
  • many OD surveys are undertaken to help calibrate traffic models - could be used to augment the SHS data - how feasible would it be to combine data from surveys which may have a variety of different methods and different definitions?

5. Accessibility data

  • need a standard approach for collecting data and calculating key accessibility measures;
  • needed to monitor whether progress is being made, and the extent to which transport is integrated with other policy;
  • "transport accessibility" measures access by people to transport systems e.g. how many live within 300 metres of a bus stop, how many jobs within 10 minutes drive of trunk road - these lend themselves to GIS based techniques. - SHS asks about "walking time (banded) to nearest bus stop".
  • "integrated accessibility" measures access by people using the transport system (irrespective of mode) to reach land uses - e.g. travel times to major cities, population within 30 minutes of an A&E unit, etc. Potentially many indicators: prioritise a few which best describe geography of Scotland and transport systems. GIS techniques helpful for some measures. - information on the percentages of households within various "drive times" of various types of education, health, retail, financial and other services for areas such as postcode sectors is available from the Scottish Neighbourhood Statistics site: www.sns.gov.UK . "Availability of Services in Rural Scotland" (Oct 2002) has maps of Scotland showing "drive times" to these services, and statistics for different types of urban and rural area: it is available from the Stationery Office bookshop or from: http://www.scotland.gov.uk/library5/rural/asrs-00.asp .
  • "freight accessibility" measures access by type of distribution centre to suppliers and markets. Prof Alan McKinnon's work on physical distribution systems defines the sort of approach which could be used.

6. Possible further analyses

  • monitor trip length by trip purpose and people group, to understand the trends in travel behaviour - National Travel Survey gives overall long-term trends in average trip length by journey purpose, and SHS provides information about variation between various groups;
  • monitor changes in travel patterns over time - check mode-proportions by purpose, car ownership, trip length (time and distance), congestion encountered etc to detect trends. Might then predict which aspects of current travel patterns are likely to change - again, NTS provides overall long-term trends in numbers of journeys by purpose, trip length, etc;
  • use road traffic data and SHS travel diary to produce factors for changes in travel by day of week, seasonality effects etc - to allow more accurate predictions of overall travel patterns from limited surveys etc
  • compare accessibility measures for different groups of people geographically or by socio-economic status - this is done for the SHS "walking time to nearest bus stop" measure..

7. Improved utilisation of existing data

  • concentrate on providing cleaned and anonymised data and/or a bureau service for bespoke analysis (rather than trying to "second-guess" what users might want);
  • ability to allocate SHS data to a user's zoning system adds considerable 'value' to the data - should be advertised;
  • combine Transport Model and SHS travel diary - do the Model's assumed base-year travel patterns match the SHS (e.g. trip frequency and mode-choice by car ownership, journey purpose etc)? if so, do Model forecasts suggest trends to be looked for in later SHS data? - SHS data should be used in the development of the next release of the Transport Model for Scotland.

8. Discussions at previous meetings have referred to other possible needs for statistics, and possible sources of data. For example, it has been suggested that information about the types of tickets/fares used (e.g. single, "all day" ticket, season ticket, etc) would help to understanding travel behaviour, and that bus companies' electronic ticketing systems could provide a wealth of data. However, although more and/or better data might be available in theory, it may not be possible to obtain them for a number of reasons, such as concerns about commercial confidentiality, the costs to the data suppliers of collecting and providing the information, the possible incomplete coverage of and/or differences between operators' systems, and the costs of receiving, processing and analysing such data.

9. Members of the Committee are asked for their views on (e.g.):

  • the needs for more statistics about Transport in Scotland;
  • the uses to which any additional information would be put;
  • the practicalities of obtaining, processing and analysing the kinds of data that they feel are required;
  • the priorities which should apply to the different possibilities.