@John_S (among others) I've previously raised the issue of the comprehensibility of diagram 618.3C signs used for "School Streets" (
TSRGD 2016 Schedule 8 Part 2 Item 2). In
this post I argued that the signs on Cumberland Road, Ealing were three times the complexity of the most complex days and times shown for these signs in the Traffic Signs Manual and that this caused cognitive overload.
In 2011 as part of their
Traffic Signs Policy Review, DfT commissioned
research into the understanding of traffic signs. A panel of 820 people were shown a selection of signs and asked questions about them. Each sign was shown to a minimum of 200 people.
Among the signs tested was diagram 959 (now with added motorcycle as diagram 959B
TSRGD 2016 Schedule 9 Part 4 Item 10). This sign for the start of a nearside with-flow bus lane has at its bottom a panel with the period of operation. In the sign which was tested this was:
Mon - Fri
7 - 10 am
4 - 7 pm
The survey reported as the Key Area of Misunderstanding
Taking in time restriction when seen on the move (78% of those shown sign statically got all comprehension questions correct compared to just 42% of those who saw it dynamically)
Diagram 959/959B uses an x-height for the text of 50mm. Diagram 618.3C uses an x-height of 37.5mm. If seeing the times dynamically halved respondents' ability to process the information, imagine what effect using text which is 3/4 the size would have.
That's ignoring the other difference between diagram 959 and diagram 618.3C as used in school streets signs: the complexity of the times used. For Ealing's sign it was:
Mon - Fri
8.15 - 9.45 am
2.45 - 3.45 pm
In my earlier post I suggested that the way to compare complexities was to count syllables:
Traffic Signs Manual: Mon to Sat Ten to Four − 6 syllables
Diagram 959 Test: Mon to Fri Sev-en to Ten Four to Sev-en: 11 syllables
Ealing: Mon to Fri Eight Fif-teen to Nine Fif-teen Two For-ty Five to Three For-ty Five − 19 syllables
That's where I got the figure of three times the complexity before. For the test it's 1.8.
I also drew attention to DfT's advice in paragraph 6.2.5 of Chapter 3 of the Traffic Signs Manual:
6.2.5. If the entry restrictions change during the day or on different days of the week, a variable message sign is recommended to avoid a complex legend that can be confusing and difficult to read. In this case, the upper panel should not include a time period. The sign should show a complete blank grey or black face, as defined in Schedule 1, during the times when the zone is not operational. The lower yellow panel can be displayed on the variable message sign only during the operational period of the zone (i.e. when the upper and middle panels are displayed).
I hope that this will help those fighting PCNs issued for contravening these signs. It's one thing to look at an image of a sign. It's quite another to see a sign as you're driving along. When it is used in residential streets with parked cars around, diagram 618.3C doesn't make sense. It's headed "Pedestrian and Cycle Zone", yet what you're seeing is an ordinary residential street rather than a main shopping street. The Scottish version with flashing lights, diagram 618.3D,
TSRGD (Scotland) 2022 Regulation 5.—(4)(b) makes much more sense. It would be even better if they replaced the words at the top with "School Zone".
