Lumeitalia
A comparison method for luminaires intended for motorway and major-artery lighting: what to look at, what to ignore, how to make data comparable.
Comparing two datasheets is not the same as comparing two installations. In motorway and major-artery lighting projects the right choice only emerges by simulating both solutions in the real geometry and assessing their behaviour over time. On motorways and main extra-urban roads, lighting is concentrated on interchanges, service areas and high-risk sections, where visual continuity is a safety requirement.
The regulatory reference for motorway and major-artery lighting is not a single document but a coordinated set of standards covering performance, safety and environmental impact. In design practice the following documents drive the main choices.
The first step is checking that data come from homogeneous test conditions and that photometric files refer to the configuration actually offered, not to a different variant of the same family. Comparing data gathered under different conditions produces arbitrary conclusions, however precise the numbers look.
Meaningful comparison happens in the project geometry: same grid, same heights, same maintenance factor, same reflectances. Only then can you see which solution meets requirements with lower installed power or fewer light points. Extrapolating from headline figures often leads to conclusions opposite to those of the simulation.
The lighting result should then be paired with an assessment of maintainability, spare-part availability and compatibility with the planned control systems: factors absent from the calculation but decisive over the whole life cycle.
The difficulties that most often emerge in motorway and major-artery lighting projects are not about product selection, but about defining requirements and verifying results.
An orderly method drastically reduces variations during works and disputes at commissioning. Three choices make the difference from the earliest stages.
Non-conformities found at commissioning almost always come from three causes: requirements not declared or declared without a reference standard, calculation run on idealised geometry, and an optimistic maintenance factor. All three can be avoided at zero cost during design.
A motorway and major-artery lighting project holds up over time when requirements are declared, the calculation reproduces real conditions and on-site verification follows an agreed protocol. Component selection matters, but comes later: without measurable requirements even the best product delivers a result that cannot be demonstrated. Centro Studi Lumeitalia makes its technical office available to review requirements and design checks.
Methodological note: This content is written for technical information purposes by Centro Studi Lumeitalia and does not replace the lighting design or a full reading of the standards cited. Applicable performance values are those of the standards in force at design time.
Because continuous lighting is not always the most effective safety measure: standards and design practice concentrate it on interchanges, conflict areas, tunnels and sections with documented accident rates.
With a transition zone of decreasing luminance, allowing the driver's visual adaptation and avoiding the black-hole effect.
From a written definition of performance requirements and verification conditions: this step drives every later choice and makes the result either disputable or defensible at commissioning.
Photometric files of the proposed luminaires, declaration of conformity, lifetime data declared per IES LM-80 with its conditions, the maintenance schedule and warranty terms.
