Mission Sustainability

I invite you to try an exercise of observation which clearly shows our idea:
At night, go to a 300 meter long avenue, where at the end there are semaphores working. You will be able to see clearly the lamps of the semaphores, which have between 75 and 150 watts.
Wait there until a car crosses in the same way and you also will be able to see the back lights of this car which have 5 watts. INTRIGUING, isn’t it?
The semaphores should have a different intensity, stronger at daytime, weaker at night. Nowadays are designed in order to turn change correctly in daytime; this is very logical and necessary but they should be corrected at night, diminishing his intensity, avoiding with this an unnecessary expense and a possible dazzle.
Moreover, we should extend this idea to all lights not only semaphores, is of UNIVERSAL application, indistinctly if the city is big or small. They work 24 hours a day and 365 days a year!
In Spain there are roughly 300,000 traffic lights using 1200 kilowatt-hour each of them per year.
Considering the number of hours of nights, dusks, dawns, cloudy days, we could consider a saving of 50% of that energy depending on each country......¿ Is it too much ?