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| | Methodology: The average age of rolling stock is calculated by adding up the individual ages of all rail vehicles in service and dividing by the number of rail vehicles in service. The age of each rail vehicle is the time between the date of entering into service and the end of each quarter; e.g. a vehicle which entered service in January 2000 would be, at the end of 2001-02 Q1 (30 June 2001), 1.5 years old. The date of entry into service is deemed to be the first day of the quarter in which the rail vehicle came into service; e.g. all rail vehicles which entered service between 1 April 2001 and 30 June 2001 are given a service entry date of 1 April 2001. |
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| | Where the date of entry into service is not available (essentially for rail vehicles introduced prior to privatisation) the date used is either: - 1 January in the year of manufacture of the relevant class of rail vehicle; or - The midpoint of the period over which the relevant class of rail vehicle was manufactured, e.g. if a class of rail vehicle was manufactured over the time frame March 1972 to March 1976 then the midpoint would be March 1974. A vehicle drops out of the calculations when its lease either expires or is terminated. |
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| | Notes, revisions and proposed changes: There have been no revisions to the average age of rolling stock data since the last publication.
“Rail vehicles” excludes locomotives. The refurbishment or other improvement of a rail vehicle is not taken into account in calculating average age.
There are no proposed methodological changes to average age of rolling stock at this time. |
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| | Quality:
As part of our commitment to continuous quality improvement, we will be producing a full quality report for all NRT statistics, in line with the Government Statistical Service (GSS) standards for quality reporting. The quality measures below provide a summary of the key dimensions of statistical quality. Relevance:
Users of rolling stock data are consulted for their feedback by a number of methods, including regular meetings of the Rail Statistics Management Group. We would like to know what you use this data for and would greatly appreciate if you could complete this quick on-line survey (it should take a maximum of two minutes). http://www.surveymonkey.com/s/useofNRT
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| If you have any feedback on this data or any of our statistics, please contact rstats@orr.gsi.gov.uk. |
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| | Accuracy:
Average age of rolling stock data can be subject to revisions if the Department for Transport receives any further information. Due to the Department for Transport submitting updated figures, all sector data for 2008-09, 2009-10 and 2010-11 Q1 have been revised with the average revisions being under 0.7%. Since then there have been 2 revisions to the average age of rolling stock data by sector. Any revisions will be highlighted in the notes, revisions and proposed changes section of the relevant tables/charts and on our revisions log, available on the ORR website:
http://www.rail-reg.gov.uk/upload/xls/stats-revisions-log.xls
Timeliness/Punctuality:
The latest data in this release refer to 2012-13 Q4, 1 January to 31 March 2013. |
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