Simon Barker:
One advantage of the diagonal black bar is that the maximum speed limit may depend on what class of vehicle you may be driving. The speed limit for a truck can be different for a car on the same stretch of road. The black bar sign simply says "national speed limit applies from here on".
Thanks for your observation, Simon. The rule is drive at the lower of the indicated speed limit for the road and the speed limit for the vehicle in question. This has always been the case. Until fairly recently the max speed for a heavy goods vehicle on a single carriageway road was 40 mph. This was the case whether a national speed limit applied or another one, for instance 50 mph. There is no need for a special "national" sign to cater for this.
The so-called "national" sign dates back to when there was no speed limit on many open roads, and that is what it indicated then. It is understandable that when national limits were applied to all roads not subject to a lower limit, this sign was retained and redefined to its present meaning. This would have been fine as an interim arrangement, avoiding the need to replace a great many signs. I suggest the "national" sign is now well past its use-by date. This is just another example of the Government at snail's pace applying piecemeal amendment after amendment to our traffic regulations, culminating in the complicated arrangement we have now.
If we want to make things easier for all classes of vehicles and their drivers sharing the roads, perhaps we should consider the continental idea of indicating the speed limits for heavy vehicles on the back.
Simon Barker:
One advantage of the diagonal black bar is that the maximum speed limit may depend on what class of vehicle you may be driving. The speed limit for a truck can be different for a car on the same stretch of road. The black bar sign simply says "national speed limit applies from here on".
Thanks for your observation, Simon. The rule is drive at the lower of the indicated speed limit for the road and the speed limit for the vehicle in question. This has always been the case. Until fairly recently the max speed for a heavy goods vehicle on a single carriageway road was 40 mph. This was the case whether a national speed limit applied or another one, for instance 50 mph. There is no need for a special "national" sign to cater for this.
The so-called "national" sign dates back to when there was no speed limit on many open roads, and that is what it indicated then. It is understandable that when national limits were applied to all roads not subject to a lower limit, this sign was retained and redefined to its present meaning. This would have been fine as an interim arrangement, avoiding the need to replace a great many signs. I suggest the "national" sign is now well past its use-by date. This is just another example of the Government at snail's pace applying piecemeal amendment after amendment to our traffic regulations, culminating in the complicated arrangement we have now.
If we want to make things easier for all classes of vehicles and their drivers sharing the roads, perhaps we should consider the continental idea of indicating the speed limits for heavy vehicles on the back.
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