The lighting should assist the road user to travel to their destination safely and securely at high speed, dependant on the prevailing weather and traffic conditions. Any object at the road edge must be visually detectable without excessive and obtrusive light encroaching on the immediate surroundings.
Once the lighting design requirements and budgets are established it is important to select an energy efficient, practical to install and maintain luminaire and lamp combination.
Energy costs can be minimised with a control system switching and dimming the lighting to correspond to traffic volumes and weather conditions. Energy consumption and operational functionality can be measured remotely from the same system. Long life energy efficient lamps appropriate to the task should be installed.
Ease of installation, maintenance and end of life recyclable disposal are pre-requisites for luminaire selection. Luminaires should be well sealed, with high maintenance factors, and designed to minimise the frequency of cleaning.
The objective is to meet designed light levels with good uniformity and glare control, relevant to the conditions and geography. The column mounted luminaires should be located to minimise the risk of impact, yet blend effortlessly with the surrounding landscape.
Careful design of the layout of columns can assist the driver both by day and by night by giving visual guidance about the route of the road ahead, such as curves.