Whether there are ANPR cameras installed or not it is still an offence to enter a weight restricted road without good reason to do so (loading or unloading, access or diverted by police). To use the weight restricted road just because you have always used the route before restriction or its a bit quicker is not reason enough. If you are entering a weight restricted road for unloading or loading you must use the shortest route possible. Must agree with the op that the signage is poor.