If you are unable to properly observe signage, you shouldn't be driving. To fail to observe signage is de facto driving without due care and attention.
One of the things I do for my living is to design human interfaces, so I have some experience in dealing with the ways that people deal with information and signs (in the broader sense).
The CPZ sign is a complex, compound sign delivering many pieces of information to a driver
while his vehicle is in motion.
It is a different beast to most others that serve this function - the language of signs giving Warning and Orders developed by the Warboys report in 1963 were admirably simple and direct.
A sample CPZ sign from
Haringey contains five elements to assimilate: the name of the area, a code presumably for residents' parking, the label of a Controlled zone, the No Waiting icon and, finally, the hours of operation.
These from
Richmond and
Islington's web sites (they chose these as exemplars for the public!) have a small essay to take in.
You not only have to observe and understand the times when the CPZ in operations, but additionally interpret them based on what day of the week and time it is. Islington's have the added benefit that the information displayed on the sign itself changes regularly, depending on whether Arsenal are playing at home or not. You have to read and interpret it separately every time you pass.
A trained individual, such as a pilot, can take in about eight or nine messages simultaneously. Mere mortals, such as most car drivers, will be hard pressed to take in more than about five messages.
There will likely be many other road signs around that also require attention. CPZs may be accompanied by 20 mph zones, traffic calming measures, bicycle route directions and a plethora of others signage. Competing for your attention are also your speedometer and ordinary hazard awareness and anticipation.
There has been much discussion about
information overload in road research circles. Authorities in Wales, Kent and elsewhere have been going about
decluttering their roadsides.
In amongst all of this, you may observe the sign, and that some kind of No Waiting restriction applies, and even (with some mental effort) take in when the restrictions apply.
However, short term memory extends from two up to about twenty seconds in most circumstances, thirty at the outside. After that, the memory must be rehearsed, usually by repetition of some sort, so that it may be retained, used and acted upon.
It may not be a coincidence that under the 1964 Regulations, things like parking times were placed on plates at the roadside - informative at the point of use, but not distracting to people driving by.