Astronomical clock

Of course, such a system cannot take account of the weather situation. If operation is to be controlled with minimal light values to save a maximum of energy, the system will switch the lights on far too late in bad weather and result in unacceptable lighting conditions. Avoidance of that risk will necessarily be at the expense of energy saving as the system would have to be switched on clearly earlier and off much later. Another detriment is the decentralised layout. Any kind of reparameterisation means enormous expenditure as each station needs to be controlled separately.