Lumeitalia
Intervention method on an existing motorway and major-artery lighting installation: survey, requirements, solution and verification.
This technical scenario is a methodological outline built by Centro Studi Lumeitalia on recurring situations, not the description of a specific project. 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. It shows how to approach the retrofit of an existing motorway and major-artery lighting installation when structural constraints prevent starting from scratch.
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 existing installation has end-of-life sources, luminaire positions constrained by existing structures and incomplete or missing documentation. Consumption is known from bills but not broken down by zone, and there are no baseline measurements of the current condition. This combination is the norm, not the exception.
The first step is the survey: real geometry, actual positions and heights, condition of supporting structures and of the electrical installation. The second is defining requirements per the applicable standards, explicitly stating what is to be achieved. The third is calculation on constrained geometry, which often shows that simply replacing luminaires is not enough and that optics or aiming must be revised.
The critical points that most often emerge in such works concern avoiding abrupt transition zones between lit and unlit sections and keeping maintenance feasible with minimal lane closures: both must be addressed during the survey, because discovering them on site means variations.
Verification needs a reference: if no measurements of the existing condition exist, they must be taken before the works at the same points that will be used at commissioning. Without this step, improvement remains a claim. The before-and-after comparison, run with the same protocol, is the only element that makes the achieved result demonstrable.
The same principle applies to energy: baseline consumption must be reconstructed over a representative period and normalised to operating hours, otherwise the calculated saving is not comparable.
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.
