Urban public transport with underground light rail systems requires a costly transport infrastructure. For this purpose, life cycle costing (LCC) is a useful economic evaluation tool for determining and optimizing the initial and follow-up costs of subway light rail systems over their lifetime and thus also for organizing the maintenance intervals of subway stations, tunnel facilities and safety systems. The modeltheoretical considerations are validated on the basis of an existing underground light rail line. The presented concept is based on a published recommendation on life cycle costing of DAUB, the German Tunneling Committee and national ITA member.