Changes to core indicators letter

13 May 2005

Calculation of National Accessibility Core Indicators

Since the original methodology for the calculation of the national accessibility core indicators was agreed and documented in the Technical Guidance, we have been considering changes in order to streamline their calculation for 2004. We are therefore proposing the following simplifications in the details of the calculations to reduce the run times or in response to comments, and would be grateful if you could please pass this information onto your local authorities.

These changes are to be implemented for the calculation of the 2004 national accessibility core indicators, and a separate working group is being set up to consider how to calculate the 2005 core indicators. The changes to the core indicators do not necessarily imply that local indicators and targets currently being developed by authorities need to change. We know that local authorities and their partners will have more detailed data which they are encouraged to use in the production of their local indicators. They will also be better placed to consider which type of indicators and targets best demonstrate improvements to accessibility relating to their local priority areas. Authorities should therefore produce local indicators and local targets which most suit their individual situation (including those which may not necessarily be related to journey time - see paragraphs 7.23 - 7.28 of the accessibility planning guidance).

Aspect	Specification in Guidance	Proposed Change	Reason
Frequency	Annual	Core indicators will be calculated for 2004, 2005, 2007, and 2010, rather than annually.	Core indicators are not likely to change significantly year on year (unlike local indicators which should be more responsive to actions taken to improve accessibility).
Geography	Wards	Core indicators will be published at Census Super Output Areas (SOAs) level, as well as wards, in line with ONS standards. The core indicators will also be published at Local Authority level.	This is an additional level which will provide authorities with indicators relating to yet smaller areas within their authorities.
'Access to major centres' indicator	Measuring access to major centres	This indicator will now be "% of a) households; b) households without access to a car within 15 and 30 minutes of a supermarket by public transport". The data to be used for this has been sourced, and DfT are working to make this available to local authorities shortly.	This allows us to focus on major food centres rather than major centres and so better reflects access to food shopping. The working group will further consider this for the 2005 core indicators.
Walk time/distance	No maximum defined	There will be a maximum of 2km in rural and urban areas.	This helps to cut down the amount of data included within the national runs with very little impact on the indicators.
Walk time/distance	Calculated exactly from road network	The walking elements of the core indicators will be "crow flies" with curvature correction.	We acknowledge that using this method will inevitably give inaccurate results near barriers e.g. rivers/canals, motorways, railway lines etc. However, using crow flies for the core indicators will greatly speed up the calculation process. Subject to additional work with CLWGAP, the plan is that the core indicators from 2005 onwards will be calculated using the actual road network. Local authorities are encouraged to continue to base their local indicators and targets on actual networks.
Road network	Mastermap ITN layer	OSCAR Asset Manager will be used for the road network, rather than Mastermap ITN. As noted above, this will only be used for cycling, not walking, which will be done on a 'crow flies' basis.	Accession is not yet able to use Mastermap. However, this is currently being addressed and should be ready for the calculation of the 2005 indicators.
Time periods	Six time periods, varying by indicator.	Just one two-hour time period will be used, from 7.00am to 9.00 am for all of the core indicators.	Simplification in order to speed up calculation of core indicators. Authorities may chose to use the six time periods in respect of local indicators and targets.
Traveline data, 2004	Whole of GB	As data for London are not currently available in the correct format for use with Accession, the core indicators for areas adjoining London will be distorted. Traveline data for regions adjacent to London will contain details of bus services originating from the neighbouring authorities into/out of London, and na tional rail data for London will be included.	We are hoping that complete London dataset will be available for the calculation of the 2005 indicators.
Future Traveline data	Snapshots will be taken twice a year, in May and October, though DfT will only use October data.	Snapshots will be taken once a year, in October, with the next data snapshot to be taken in October 2005.	Two snapshots were not considered necessary on a national basis. If authorities have their own public transport data, they can, of course, take snapshots whenever they like.
Destination data	Include local information provided by authorities to supplement central data sets.	We will use just the national dataset of destinations (with the exception of food shops) which were included on the original data disk sent out in October 2004. Changes notified so far will not be considered in the 2004 core indicators.	As we do not have a complete picture from all local authorities, we will use the consistent set of data for the 2004 indicators. However, we will put in place a process for local authorities to provide updates to the central data relating to their area. This will be made available to neighbouring authorities and used to calculate the 2005 indicators.
Scotland and Wales		Destinations in Scotland and Wales will not be included in the calculation of the national accessibility core indicators.	Unlikely to have a significant impact on core indicators. However, we will reconsider for 2005 if authorities bordering Scotland and Wales consider that a significant number of people from their areas access services across the borders.
Access to work: Destinations	Census data on number of jobs, by OA.	SOAs rather than OAs will be used as notional employment locations. A threshold of a minimum of 500 jobs available within an SOA has been assumed, which means that only a third of SOAs will be classed as destinations. We will let authorities have these data shortly.	This significantly reduces the number of calculations necessary. Local authorities may wish to choose a different approach for their local indicators and targets based on actual places where jobs are available - partners in JobCentre Plus may be able to advise on the type of data available.
PT Modes	Flexibly routed transport if available, include contracted school bus services where appropriate and where available.	Flexibly routed transport and contracted school bus services will not be incorporated within the first set of core indicators.	We do not have information on all flexibly routed services. However, we will aim to collect this from local authorities in order to include it in calculation of the 2005 indicators.

The core indicators are currently being calculated and we now anticipate these will be available in July. As mentioned in our letter of 21 February 2005, authorities should continue to work on their accessibility strategies and not wait for the core indicators to become available.

With regards the public transport database, we are aware that a number of authorities have raised concerns about the quality of the data. These problems arose from a number of technical issues which have now been fixed, and the data has been reprocessed. The updated database was made available last week, and if local authorities still require a login to access this, they should contact Thales at nptdr.datamanager@thales-is.com. Please note that the data can now be downloaded from a website, as well as via ftp.

If you need any additional information on any of the above issues, please do not hesitate to contact me.

Helen Pattington

For related documents, pages and internet links, see the column on the right.