EN 13201 — what the standard requires and how the classes work

The Five Parts of the Standard

The road-lighting series comprises the technical guidance document CEN/TR 13201-1:2014 and the standards EN 13201-2 to -5:2015. Part 1 helps the client select a class that is specified through requirements in Part 2, calculated under Part 3, measured under Part 4 and evaluated for energy performance under Part 5. Trafikverket — Vägbelysningshandbok 2024

M Classes — Carriageways and Luminance

M classes apply to areas for motorised traffic and use luminance as the primary criterion — not illuminance in lux. EN 13201-2:2003 used the ME and MEW designations. Because the requirements and the surrounding-area criterion changed between editions, M3 must not be treated as a direct equivalent of ME3a or ME3b.

M classes apply to carriageways in segments where vehicles move at relatively higher speeds. A complete DIALux model for an M class requires:

• The r-/R-table prescribed or verified for the project’s actual road surface
• For the M-class luminance calculation, the observer’s eye is positioned 1.5 m above the road and 60 m ahead of the calculation field. The calculation of f_TI follows the separate observer procedure in EN 13201-3.
• Calculation point grid per Part 3

The table mainly shows the dry-road requirements and surrounding-area criterion for M1–M6 under Part 2; it is not a complete reproduction of every requirement:

Lm = maintained average luminance. Uo = overall uniformity (min/average). Ul = longitudinal uniformity (min in lane/max in lane). f_TI = threshold increment (disability glare). EIR is the abbreviation for Edge Illuminance Ratio, and R_EI is the symbol: average horizontal illuminance on a strip immediately outside the carriageway is compared with that on a corresponding strip immediately inside it. The strips are one traffic-lane width, and each side is assessed separately. R_EI is used only where adjacent traffic areas do not have their own requirements; the 0.35 and 0.30 values are tentative minimums and may be amended by national or individual scheme requirements.

EN 13201-2:2015 also includes the wet-road criterion U_o,w = 0.15 for M1–M6 where applied under national requirements. EN 13201-2

The Parameters Explained

P Classes and C Classes

P classes (P1–P6) apply to pedestrians, cyclists and low-speed areas such as footpaths, cycle paths, residential streets and car parks. Here horizontal illuminance (lux) is used instead of luminance, because there is no unified moving observer. EN 13201-2:2003 used the S designation for the corresponding historical class family.

Em = maintained average horizontal illuminance; Emin = maintained minimum horizontal illuminance. Per EN 13201-2:2015, Table 3.

C classes (C0–C5) apply to conflict areas with complex traffic: intersections, roundabouts, pedestrian crossings and other conflict areas. C classes use horizontal illuminance. EN 13201-2:2003 used the CE designation for the corresponding historical class family.

The Maintenance Factor (MF) — One of the Most Important Variables

The maintenance factor (MF) converts initially calculated photometric performance into maintained performance at the selected point in time. MF must be determined for the specific project using a documented method, such as ISO/CIE TS 22012:2019. ISO/CIE TS 22012:2019

• Documented lumen maintenance for the selected LED module and operating point must form part of the basis.
• Luminaire dirt depreciation must be assessed from the environment and cleaning interval.
• The project’s strategy for failures, replacement and planned maintenance must be documented.
• Road-surface reflectance properties are handled through the selected r-/R-table, not through an arbitrary additional MF component.

No generic percentage or MF is universally correct. The initially calculated luminance or illuminance must, after application of the project-specific MF, meet the maintained class requirement. The calculation documentation should state the method and assumptions; more on the difference between modelled and real performance is available in DIALux does not calculate everything.

How to Choose the Right Class

CEN/TR 13201-1:2014 provides a starting method for class selection. The final class requires a project-specific assessment; a road type alone cannot be translated into a particular M, C or P class. The assessment includes:

• Traffic — speed, flow and composition.
• Users and areas — the user groups and traffic areas concerned, and whether adjacent traffic areas have their own requirements or are to be assessed using R_EI.
• Geometry and visual complexity — including conflict points, the navigation task and road layout.
• Local conditions — ambient lighting, weather conditions and particular user groups.

Energy Performance — PDI D_P and AECI D_E

EN 13201-5:2015 defines two complementary indicators. PDI, with the symbol D_P and unit W/(lx·m²), relates system power to illuminated area and maintained average illuminance. AECI, with the symbol D_E, relates total energy consumption over a specified year to the illuminated area and is expressed in Wh/m²; kWh/(m²·year) may be used as a scaled presentation unit. D_E is therefore the symbol for AECI, not a separate metric.

PDI and AECI are used together. A direct energy comparison is meaningful between alternatives for the same project, geometry and lighting requirements; equal road length alone is not a sufficient basis for comparison. When the indicators form part of a tender, the calculation assumptions, operating profiles and illuminated area should be stated.

Five Points for Procurement

1. Specify M class, not just lux. For carriageways, state the class, maintenance interval and the r-/R- or N-table prescribed or verified for the project’s road surface, so that the calculated MF and class compliance can be verified.
2. Require a calculation file in DIALux or Relux. Without a complete editable project file with correct observer position, R-table, and MF it is difficult to verify that class values are actually met.
3. Specify the surrounding-area requirement. State R_EI where it applies, or specify separate P or C class requirements for adjacent traffic areas.
4. Define field measurement. State the timing, measurement conditions, responsibilities and treatment of deviations as project-specific contractual conditions. EN 13201-4 does not prescribe a general 12-month deadline.
5. Request PDI and AECI. Include both D_P and D_E per Part 5, with common calculation assumptions, as comparison criteria in LCC (life-cycle cost) procurements.