Single/Double Summer Time Position Paper

  • Published: The Royal Society for the Prevention of Accidents (RoSPA), 2005
  • Authors: The Royal Society for the Prevention of Accidents (RoSPA)
  • Date Added: 18 Mar 2013
  • Last Update: 12 Feb 2016
  • Format: pdf


To review the research about Single Double British Summertime


Literature Review

Key Findings:

  • The introduction of SDST would make the difference in Scotland more pronounced. For example on 31 December 2002 under SDST, dawn would be 9.06am in London and 10.20am in Stornoway (Isle of Lewis), while dusk would be 16.39 in Stornoway and 17.01 in London. This has led to considerable opposition to the introduction of SDST in Scotland, where many feel that the greater light available in the evening would not compensate for the longer dark periods in the morning.

  • Road casualty rates increase with the arrival of darker evenings and worsening weather conditions. Every autumn when the clocks go back and sunset occurs earlier in the day, road casualties and the casualty rate rise.

  • The effects of clocks going back in October are greatest for the most vulnerable road users. In 2004, pedestrian deaths rose from 56 in October to 76 in November and 78 in December.

  • Road casualty figures during the morning (7am-10am) and afternoon (4pm-7pm) for the period affected by time change in the two winters (1966/67 and 1967/68) before the experiment and in the first two winters (1968/69 and 1969/70) when BST was retained were analysed. The data showed that keeping British Standard Time had resulted in an 11 per cent reduction in casualties during the hours affected by the time change in England and Wales and a 17 per cent reduction in Scotland. The overall reduction for Great Britain was 11.7 per cent. Although casualties in the morning had increased, the decrease in casualties in the evening far outweighed this.

  • Overall, about 2,500 fewer people were killed and seriously injured during the first two winters of the experiment.

  • However, the 1968/71 experiment coincided with the introduction of roadside breath tests and the 70mph speed limit, which may have affected the casualty reduction figures.

  • The Agricultural Development Advisory Service (ADAS) published a report in 1995 examining the advantages and disadvantages of three options for Europe. The model applied to the UK indicated that a change to SDST would lead to 0.75 per cent fewer people being injured on the roads each year and 1.3 per cent fewer killed or seriously injured (on 2001 figures, about 527 fewer deaths and serious injuries).

  • RoSPA issued a questionnaire to seek the views on SDST of 189 organisations, 34 organisations completed the questionnaire in full, of which 14 (41 per cent) would ‘strongly approve’ of legislation to introduce SDST, 13 (38 per cent) ‘somewhat approved’, 3 (9 per cent) ‘somewhat disapproved’ and 4 (12 per cent) would ‘strongly disapprove’ of such legislation. Therefore of the respondents, 3 to 1 were in favour of SDST. RoSPA acknowledges the limitations of the findings from this survey, which represents only a small sample and not all organisations had canvassed the views of their members.

  • The only way to reach a conclusion about the effects of a move to SDST in this country, to align the UK clock with that of its European neighbours, is to conduct an experiment similar to that held during 1968/71. A trial implementation of SDST over at least two years, with modern evaluation methods and all data correctly and comprehensively recorded, will result in data that is unequivocal in terms of casualty savings and could cover much wider issues also. Such an experiment would give people an opportunity to experience the change for themselves and may be useful in crystallising opinions.

  • Since the 1968/71 experiment, the road environment and people’s travel habits have changed enormously. Society is more reliant on the car, fewer children walk or cycle to school, opportunities for leisure activities are significantly greater, people take holidays more frequently and overseas travel is much more common. The advancements in communication technology have opened up the opportunities for worldwide trade even further. Even weather conditions are changing as the effects of global warming are felt. None of the research conducted to date is able to address these factors successfully, hence the need for a new trial.


SDST, 1968/1971 experiment, Road casualties


This position paper outlines the history of the debate.