Road lighting is so much in favor using streetlights instead of post tops. Even if the road width is less, traffic flow is minimal or it is a private road, still street lighting fixtures are used without a second thought.

While street lighting is indispensable for roads with high speed traffic and wide roads, there are many instances where post top lighting could be sufficient to achieve the required lighting levels.

Street lights even in small residential roads are quite common. This creates light trespass into residential buildings affecting the sleep quality of residents and eventually their health in the long term. 

Another point is that the same lighting levels are specified regardless of it being a highway or secondary road or private road. There are different lighting levels recommended for different road types depending on the traffic density, speed and diversity of road users.

And it becomes even worse, when street lights are used to illuminate roads completely covered with trees. Such an arrangement, where the street light poles are typically from 8m to 12m height and well above the tree foliage, creates a highly non uniform lighting level on the road surface.

In DIALux lighting software, the standard tree, is completely opaque and does not provide a realistic visual.

To demonstrate the difference between the use of street lighting and post top lighting for certain type of roads, always wanted to create a tree with holes, to simulate the light obstruction by the tree foliage. But using 3ds models of realistic trees increases calculation time exponentially. So a simple obstruction in the shape of a tree with holes to simulate the light passing through the foliage was necessary. 

Started to learn blender recently and created tree shaped obstruction with holes, to simulate light passing through the foliage

Another variation with more holes to simulate lighting levels through sparse foliage.

While it will never provide accurate lighting levels, as the distribution of leaves would be completely unpredictable, this simple tree model was very useful to convey the obstruction created by trees preventing uniform lighting. 

Probably it can help decide between a high streetlight or low height post top. As full cut off post tops at 4m to 5m would be below the foliage, it would create a shadow free road lighting.

As can be seen from the last images, the road surface is free from shadows and there is also minimal light pollution on the vertical axis.

What do you think? Share your comments below.

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I aim to spread awareness on the subject of Healthy Lighting designs to facilitate co-creation of healthy lighting at home, work and other social spaces. My posts can be accessed at Archinect  and Linkedin Group. I also have a self published book "Healthy Lighting of your Homes" at Amazon.