In this paper, we propose an adaptive survivability admission control algorithm using a backup path for high-speed networks. For each call request, the proposed algorithm selects a combination of working path and backup path. Two BP selection methods, min-cost and minexpectation, are suggested. Computational experiments indicate that the proposed algorithm significantly reduces the consumption of backup capacity while still maintaining 100% survivability upon a single link failure and near 80% survivability upon double link failures.