Tunnels, bridges and roadways are infrastructure designed to be in function for a relatively long lifetime. In this assignment the tunnel lifetime is set to 100 years whereas the bridge is designed to be in function for 100 years as well. The main causes for degradation within the systems are typically related to traffic or water ingress, meaning the interventions are either preventative or replacements.

The integrated system combines the steel bridge, tunnel rock support and tunnel anticorrosion. The main challenge of aligning the maintenance strategies, is aligning the interventions in such a way that the operational down time is minimal. Based on the individual research conducted,the interventions implemented in the combined system are the following:

Bridge part:
-Partial replacement of deck every 15 years (MSDO)
-Full deck replacement every 30 years (DR)
-Maintenance works every 5 years according to current regulations (M)

Tunnel part:
-Replacement of steel bolts every 20 years (B.r)
-Spraying of anticorrosion coatings every 10 years (AACL)
-Maintenance works every 5 years according to current regulations (M.r)

 

The alternative maintenance strategies are evaluated by ranking in order to select the optimal option. The main goal of this evaluation is to minimize the duration of operational down-time and maximize the time between two interventions causing operational down-time. In total, 266 options are ranked based on our included interventions.

By use of the Pareto frontier the graphical illustration becomes clearer. Here, the defined priorities are to minimize operational down time and maximize the time in between. The blue line represents the Pareto frontier and the best option is shown clearly as the marked point in the top left corner.