How to light a highway - Mathieu

Energy efficient lighting installations for highways must provide safety for high speed and eventually heavy traffic. Colour rendering aspect is of secondary importance.

Photometric requirements

The application of the new CIE publication Nr.115-2010, taking into considerations several parameters linked to the traffic and the road configuration, leads to classify a motorway as being generally M3 or M4.

The values of the lighting criteria to respect are the following:

Class M3

Lave = 1.0 cd/m²

Uo ³ 0.4

Ul ³ 0.6

TI £ 15%

SR ³ 0.5

Class M4

Lave = 0.75 cd/m²

Uo ³ 0.4

Ul ³ 0.6 

TI £ 15%                 

SR ³ 0.5

 

Light sources

The colour rendering is of lower importance compared to lighting commercial and pedestrian areas in city centres. Therefore, high-pressure sodium lamps are extensively used for this type of road (in some countries – Belgium for instance – low-pressure sodium lamps are also used).

However, white light can also be selected when more importance is given to a better colour rendering, particularly in areas closer to the cities. Then, metal halide lamps could be an option, but the use of LED luminaires is also possible. This type of light source needs reduced maintenance due to its very long lifetime.

 

Luminaires

The luminaires chosen to light motorways should have a high level of tightness (at least IP 66), in order to maintain as long as possible initial performances throughout the lifetime of the installation.

The resistance to mechanical impacts must correspond at the very least with the IK 08 degree, in line the IEC 62 262 standard.

These luminaires will preferably comply with the Circle Light Label as defined by Schréder.

 

Installation layout

When the width of the central reservation between the two roads does not exceed 10m, the most appropriate installation layout consists of installing the lighting poles in the axis of this central reservation. Each pole will hold 2 luminaires, one oriented towards each lane.

The height of the poles depends first of all on the total width of the roads together with the set-back of the luminaires from the border of the road. The mounting height of the luminaires is in general 12m or higher.

When the central reservation is too wide (over 10m), a more efficient solution is obtained with two rows of poles in opposite situation, inside the central reservation or along the external borderline of each road.

The efficiency and the functional aspect of the lighting installation is of main importance. The aesthetic appearance can however be preserved by using well and nicely designed functional luminaires. Easiness of maintenance operations (lamp replacement) is quite important to reduce maintenance costs.

The lighting installation shall be energy efficient, with a SLEEC-L value (Street Lighting Energy Efficiency Criterion Luminance based) being at a maximum equal to 0.8 W/cd/m²/m².

An accurate knowledge of the light reflection characteristics of the pavement is of primary importance to meet the above efficiency criterion. These characteristics can be measured by our specific equipment called Memphis.

The following drawing shows a typical installation for a highway.
how to light a motor highway drawings
FURYO- how to light a motor highway

Examples of lighting installations for motorways

 

Motorway section with 2x3 traffic lanes, central lighting installation (poles in axis of 6m width central reservation) of FURYO3 luminaires fixed on 14m poles with a spacing of 62m. The FURYO3 luminaires are equipped with 250W high-pressure sodium lamps in order to provide luminance results complying with criteria of road class M3 (1cd/m²).


Motorway section with 2x2 traffic lanes, central lighting installation of AMBAR 3 luminaires fixed on 12m poles with a spacing of 50m. The AMBARmotor3 luminaires are equipped with 150W high-pressure sodium lamps in order to provide luminance results complying with criteria of road class M3 (1cd/m²).

AMBAR - how to light a motor highway