SURROUND RATIO CALCULATION

[kikeblackberry]

Hi
I know EVO is keeping up to date with European standards and for road lighting new one is EN 13201: 2015 but some projects have to be calculated per earlier version EN 13201:2004. One of the differences between them is the calculations of surround areas adjacent to the road. Older version define the lighting quality parameter of surround ratio (SR) and the newer adopted the edge-illuminance ratio (EIR).

Regarding calculations of SR, I have been made some calculations based on DIALux results and I have found DIALux always calculate the SR in the same way: For roads wider than 10m, the width of all four calculations strips are equal to 5 m and for roads less than 10 m, the width of all four calculations strips are equal to half the width of the road. No matter what size (in wide) is the the adjacent area to the road.

Nevertheless, CIE140:2000 and EN 13201:2004 indicates “The width of all four strips shall be the same, and equal to 5 m, or half the width of the carriageway, or the width of the unobstructed strip lying off the carriageway, whichever is the least.” See Figure 16 part (b) of EN 13201:2004.

What I want to know is why EVO (apparently) does not taking into account the bold and underline text before.
It would be a good improvement if these results (for all 4 strips) are included into documentation project for SR or EIR.

Regards

[T.Magenheimer]

Dear kikeblackberry,

Thank you very much for your request.

The EIR is always specified when:

- Either on both sides no evaluation field with a class for illuminance adjoins. In this case, the worst value is taken from both results.
- If only on one side there is an adjacent evaluation field with a class for illuminance. In this case, the only result is also the worst value.

EIR is always not to be evaluated if evaluation fields with illumination classes for illuminances are adjacent on both sides!

With regard to the width of the free strip, in practice the evaluation field of the outermost lane is mirrored at the curb in order to calculate EIR.

From our point of view, the road calculator works correctly.


Best regards
Your DIAL Support Team