The Rail Safety and Standards Board have set out requirements and guidance for the use, interpretation and formatting of time and date information across the network.
In the early 1800s, timekeeping across Great Britain varied significantly, with local times differing by up to 25 minutes from London time. The standardization of time began with the Great Western Railway in 1840, which synchronized clocks across its network.
Today, the rail industry relies on various time sources, including satellite-based clocks, radio clocks, and networked clocks. However, Coordinated Universal Time (UTC) is 37 seconds behind atomic clock time and 18 seconds behind GPS time, complicating the comparison of timestamps across different systems.
The RSSB has introduced a new standard for interpreting time data, addressing the multiple factors that can affect this data. This standard aims to help the industry locate, combine, and analyse data, specify new systems, and enhance cybersecurity.
The new standard encourages the broader use of UTC and the consistent formatting of date, time, and UTC time offset values, aligning with international standards.
RSSB’s Director of Standards, Tom Lee, said:
“RSSB's closest predecessor, the Railway Clearing House, led the standardisation of time across the country, publishing its first standard, about time, on the 22nd of September 1847.
“A 21st century digital railway is built on consistent and accurate time data, and our new standard supports this, helping to synchronise systems, improving real-time and post-event analysis, and enabling more effective incident investigations.”
The requirements in the new standard promote the wider use of UTC and the consistent formatting of date, time and UTC time offset values, in line with international standards. The importance of documenting a clock’s time source, time scale and capabilities to change UTC offset are also highlighted. This standard helps mitigate the risk of using misaligned time data by helping users to see that different time scales can be used, recognise that not all are the same, and that a translation may be required. Adopting these requirements also supports the aggregation of data, in real-time or post-event, for example during investigations.
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