Road lighting — classification per NEN-EN 13201

The §714 outdoor lighting guide covers the electrical safety requirements for an outdoor lighting installation: IP rating, RCD protection, mechanical protection against impact. This article covers a completely different, complementary standard that has nothing to do with electrical safety, but with photometric performance: NEN-EN 13201, which specifies how much light a road-lighting installation must deliver — a similar distinction to the one already made elsewhere between §560 (emergency escape-route lighting, NEN-EN 1838) and the workplace lighting guide (NEN-EN 12464-1).

The three main class series: M, C and P

M classes (M1-M6): for roads with motorized traffic, where the requirement is expressed as luminance (cd/m²) as perceived by the driver looking at the road surface — not simply the amount of light falling on the road.
C classes (C0-C5): for conflict areas (intersections, roundabouts) and mixed traffic, expressed as illuminance (lux) instead of luminance, because road users view a conflict area from too many different angles for luminance to be meaningful.
P classes (P1-P7): for pedestrian and cycling areas, also expressed as horizontal illuminance (lux), with requirements geared more toward recognizing people and perceived safety than supporting the driving task.

Illuminance versus luminance: why two different quantities

The difference between these quantities is fundamental: illuminance (lux) is the amount of light falling on a surface, while luminance (cd/m²) is the amount of light reflected from that surface toward an observer. For a road user on an M-class road, what matters is not how much light simply falls on the asphalt, but how much of it is actually reflected back toward them — which depends partly on the reflection properties of the road surface itself (expressed as a separate reflection class, denoted q0). For conflict areas and pedestrian areas, where there is no single dominant viewing direction, the simpler illuminance quantity is sufficient.

Additional requirements: uniformity and glare

An average level alone is not sufficient: each class also specifies a minimum uniformity — the overall uniformity ratio Uo (Lmin/Lavg) and, specifically for M classes, also a longitudinal uniformity Ul — to prevent dark "gaps" from forming between lighting columns that undermine the driving task despite an on-paper sufficient average level. In addition, the standard limits glare via a threshold increment parameter (TI, in %) and the surround ratio (SR) for sufficient lateral light spread beyond the traffic lane itself.

Choosing the class: who decides

The class to be applied for a specific road or area is determined by the road authority (municipality, province, national highway authority), based on traffic volume, speed, intersection complexity and surrounding luminance. This article covers the structure of the classification, not a ready-made selection table for a specific road situation.

Practical relevance

When designing or replacing a road-lighting installation, two independent sets of requirements must be met simultaneously: the photometric performance requirement of NEN-EN 13201 (which M/C/P class, which luminance or illuminance level, which uniformity) and the electrical and mechanical safety requirement of §714 (IP rating, RCD protection, mechanical protection of the luminaire and cabling against impact). Meeting one requirement does not replace the other.

Common mistakes

Confusing the photometric class requirements of NEN-EN 13201 with the electrical installation requirements of §714 — two completely different standards with a different purpose.
Approximating the M-class luminance requirement with an illuminance meter alone, without accounting for the actual road surface's reflection class (q0) — this gives a misleading result.
Checking only the average level and ignoring uniformity (Uo/Ul) — this can result in dark zones between lighting columns that undermine safety despite an on-paper sufficient average.
Applying the wrong class series — for example, using an M-class luminance calculation for a footpath, or the reverse — resulting in under- or over-lighting.