Technical and economic evaluation of lighting and pavement in Italian road tunnels

This work computes and compares the life cycle costs of two different road tunnel pavements and their corresponding lighting systems. The study evaluated rigid and flexible pavements during life periods of 20 and 30 years for different traffic conditions and for tunnel lengths between 750 m to 2000 m. The design of the pavements and lightening systems, and their corresponding maintenance strategies, followed the requirements stated in current Italian standards. This information was used to estimate the net present values of the construction and maintenance costs for both the pavements and the tunnel lighting systems, using official unit prices valid in Italy. The results showed that for tunnels equal or shorter than 1000 m, the option of using a concrete pavement offered a better economic and technical solution from the initial year of service in comparison to the flexible structure. For tunnels equal or longer than 1200 m, the discounted costs related to concrete pavements were slightly higher than those obtained for the asphalt pavement. However, due to the low pavement maintenance and lightening system costs, the concrete pavement reaches a break-even point in these cases after a few years of service. The results also suggest that the expected traffic level in the tunnel has a neglectable impact in the economic analyses, independently of the type of pavement or tunnel length. This study demonstrates that the quantification of the life cycle costs related with the selection of the road type is an efficient practice to support decision-making processes during the design stage of a tunnel structure.