2025 Volume 42 Issue 4 Pages 4_62-4_80
Companies are facing the challenge of modernizing software systems that have been running for decades. Incremental modernization, a strategy that improves software systems in a step-by-step manner rather than attempting to simultaneously overhaul the entire system, aims to mitigate the risk of failure. However, this approach can increase costs owing to the complexity of integrating legacy and modernized products. In this paper, we present a case study that employs a cost-benefit estimation analysis in a large-scale industrial project that underwent incremental modernization in the past. We compare the actual and estimated cost-benefit values in the context of incremental modernization. As a result, we confirmed that the cost estimates were valid, but we could not judge whether the benefit estimates were valid.