Italian road tunnels: economic and environmental effects of an on-going project to reduce lighting consumption

Tunnel lighting represents a major cost item for road managers, and particularly in Italy owing to its specific geomorphological and orographic features. In 2018, ANAS, the Italian government-owned road company launched an ambitious program to rehabilitate the lighting systems of more than 700 tunnel tubes across Italy. The Greenlight plan aims to reduce consumption and improve the management of lighting systems while minimizing the impact of works. Outdated high-pressure sodium (HPS) luminaries will be substituted with state-of-the-art light emitting diode (LED) luminaries without modifying the position and the number of the existing luminaires. The project involves an amount of 155 million euros and provides a total return over a less than seven-year period. The first phase of the project involves 147 tubes and is still on-going: 28 GWh (on average 55% of the current consumption) will be saved every year against a 30 million euro investment. More importantly, the economic benefits also have a direct impact on the environment for citizens and safety levels for road users-every year more than 17,000 t of CO2 eq. and 230 TJ from combustion of fossil fuels will be saved. The lighting quality of the artificial lighting inside the tunnel will be enhanced thanks to better uniformity and the color temperature of the luminaries. The experience presented here could be useful since other road managers may pursue a similar approach in order to balance often-conflicting environmental, economic and safety goals.