ROAD TUNNEL MAINTENANCE IN WINTER CONDITIONS - A SOLUTION TO ECONOMIC CONSTRAINTS AND SUSTAINABLE DEVELOPMENT

摘要

Maintenance plays an important role on the quantity of luminaires installed and operating both day and night in road tunnels. The range of values taken from ANSI/IES RP-22-11 or CIE-088:2004 for maintenance varies according to different parameters, including the lamp survival factor (LFS). In Nordic countries, environmental conditions are certainly the most important factor to consider in maintenance, due to abrasives, such as salt and calcium, that are brought into tunnels by vehicles; these abrasives accelerate lumen degradation.Light levels vary over time due to degradation of lamp output and dirt accumulation, which obstruct the luminous flux to reach the pavement. Depending on the cleaning cycle, tunnels are over-illuminated in order to comply with recommended practices.The black hole effect at the tunnel entrance is also more difficult to reduce during winter: there are faster and more frequent lumen variations due to snow, wet pavement and light reflections at the tunnels’ portals.Over-illumination becomes a major concern in a context of budgetary constraints and sustainable development. New technologies are now available to read and control lumen output inside the tunnel and meet recommended practices. As opposed to traditional systems, in which general purpose digital outputs are used to control a group of luminaires, Intelligent Lighting Control Systems (ILCS) use the latest available technologies to individually control and monitor every luminaire. With advanced systems, it is possible to dynamically adjust the luminaires—without over-illuminating the tunnel—by reading the real luminance levels inside the tunnel.Individually controlling each luminaire also offers the possibility to program multiple lighting scenarios and alternate luminaires. Knowing that some luminaires are always on, the use of lamp alternation will average out lamp usage, have an impact on the lamp survival factor (LSF), and extend the relamping cycle up to four times longer.Using a dynamic control system, combined with the use of illuminance cameras, an advanced system can adjust the light levels to actual needs, bringing very important energy savings all year long and even requiring less frequent cleaning and maintenance. Lamp alternation averages out lamps’ lifetime, significantly extend the relamping cycle, which will bring major savings in tunnel operational costs. To conclude, the ILCS for tunnels helps reduce costs of operating tunnels during the winter—a period in which budgetary constraints are the most important. The ILCS reduces costs in three different ways: energy savings,, extending cleaning and maintenance periods, and extending the relamping cycle.