Friday 9 July 2010
At the moment, with the exception of some roadworks signs, most British road signs currently use the antiquated 12 hour format generally, which is very language specific – as a.m. (ante meridiem, “before noon”) and p.m. (post meridiem “afternoon”) is not necessarily the same at other languages. And if you are driving, you wish to be able to see quickly at a glance without making errors (e.g. 11:00 or 23:00 cannot be misinterpreted and is unambiguous, 11am and 11pm could be misread at a glance).
Using 24 hour time is language independent, and international. By contrast 12 hours is language specific. For example regardless of notation 9h (h is the SI symbol for hours), 09.00, 0900 and 09:00 are all different notations of the same time, and mean the same internationally, but 09:00 which is the ISO 8601 standard notation is recommended. Similarly 09:30, 18:30, 00:00 all mean the same internationally. 24 hour time is an international standard, specifically ISO 8601.
The times appearing on road signs in the UK should be ISO 8601 compliant as well as 24 hour format. Examples of signs with ISO 8601 compliant 24 hour time notation are shown below. Nonetheless an example of an alternative notation (9h, 18h, etc.) is also shown.
Times when No parking zone is active in 24h format. The no parking zone signs themselves only need the "No parking" symbol and "ZONE", and also no superfluous words such as "Controlled".
No parking between 09:00 and 18:00 signs.
Standard ISO 8601 notation (left), alternative notation (right).
Standard ISO 8601 notation (left), alternative notation (right).
It is worth noting that when a "No stopping" or "No parking" sign is shown standalone, this means the restrictions apply at any time, every day, throughout the year. This means that there is no need for a supplementary plate (or equivalent) saying "At any time". Removing "At any time" removes unnecessary clutter. Just the sign alone is sufficient when a restriction such as "No parking" or "No stopping" is active all the time. These two signs are shown below:
No parking sign (left), and No stopping sign (right).
No supplementary plates means the restriction is always active.
No supplementary plates means the restriction is always active.
This is also an opportunity to replace wordy signs. For example there are signs which have supplementary plates saying "Part time signals" when a set of traffic lights (or traffic lights ahead) only operate at certain times of the day. This is not only language dependent, it is also imprecise as it does not tell us exactly when the traffic lights operate, and takes up valuable space. But at the same time, it is worth noting that part time traffic signals are operated by sensors detecting traffic levels, so in these cases "Part-time signals" can be retained.
Where traffic lights are not controlled by such sensors, showing the time the lights operate (and other information such as the days it operates if applicable) is much better and results in a much smaller and cleaner supplementary plate, and less clutter improves safety and readability at a glance. This is illustrated below:
Replacement of supplementary plate "Part time signals" with a more precise supplementary plate "09:00-17:00" in this example. The change would only be required if the traffic lights operate within precise timings.
There are other signs, however, which may have a stronger case for replacing imprecise wordy notations with actual times in 24 hour format.
We have shown that 12 hour signs need to be converted to international 24 hour format, and this should ideally be done as part of the metric conversion. This is also another opportunity to get rid of wordy signs and replace with symbolic equivalents where possible.
Part time signals are usually triggered via road sensors that analyse whether or not they are needed on a traffic-level basis. They have nothing to do with time. Due to peak time levels being high enough to trigger them, most people only see them on during certain times and think that that is when they're timed to operate - which of course is coincidence.
ReplyDelete@Simon Patterson - Thank you for your comment. You've made a very good point. Then there is probably a case for retaining the supplementary plate "Part time signals", where sensors are used to determine whether traffic lights need to be triggered or not - which sounds like most of them.
ReplyDeleteWhere the operating times were known and predictable (which is probably not true in general), then I think the times could be stated instead of the words "Part time signals".
Why not make all traffic lights using sensors? They are the most efficient. And sensors could even detect when the volume is so low that full signalization is not required. Adding give way signs and priority road signs (need to prescribe new signs for beginning of priority road and end of priority road) and sharks teeth markings at traffic lights, and replacing the meaning of flashing amber from pelican crossing to junction controlled by give way and priority road signs.
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