Optical networks employing the wavelength division multiplexing (WDM) technology are promising solutions to the ever increasing demand for bandwidth. The use of WDM allows aggregation of many channels onto a single fibre without the need of high speed optoelectronic devices for end users. In WDM networks, as the optical signals traverse multiple links their quality deteriorates due to the physical impairments they encounter. This necessitates regeneration of the signals at the intermediate nodes so that the signals will reach the destination with an acceptable level of quality. In addition, due to the frequent occurrence of fiber cuts and the tremendous amount of data transported, survivability, which is the ability to reconfigure and reestablish communication upon failure, is indispensable in WDM networks. Survivability is of critical importance in high-speed optical communication networks. These days, network survivability along with impairment-aware routing is of great interest to telecommunication system vendors, service providers and end users. This thesis work focuses on solving impairment-aware survivable routing in WDM networks. We have proposed and implemented exact and heuristic algorithms that solve survivable regenerator placement and survivable impairment-aware routing problems in WDM networks.