Abstract: Highway engineering in the permafrost regions of the Qinghai–Tibet Plateau has long been plagued by the chain deterioration of “temperature rise–thaw settlement–cracking,” which seriously threatens the long-term safety of major transportation infrastructure. It is urgent to systematically sort out the distress characteristics, clarify the key control thresholds, and establish a long-term effective prevention and control technology system. Based on more than 60 years of service data from the Qinghai–Tibet Engineering Corridor and monitoring data of a 134 km typical section of the Qinghai–Tibet Highway, a four-dimensional dataset of “ground temperature–degradation rate–ice content–service life” was established. The survival analysis method was used to quantify the key thresholds of engineering service life. Through 13 years of continuous observation, the long-term performance of traditional prevention and control measures was systematically evaluated, and the demonstration effects of new active cooling and intelligent early-warning technologies were summarized. Results show that: (1) The mutation thresholds of engineering service life are an annual mean ground temperature of −1.5 °C, a permafrost table degradation rate of 20 cm/a, and an ice content of 60%. (2) The composite embankment with “ventilation ducts + block-stone layers” has both cooling and anti-cracking advantages, with the lowest demand for secondary maintenance. (3) New technologies such as dispersed ventilation, unidirectional heat-conduction panels, solar-powered thermosyphons, and the Beidou-IoT early-warning platform have shown good performance in field applications.A full-life technical system of “active cooling + passive themal insulation + intelligent maintenance” is proposed, which can provide standardized solutions for the construction and maintenance of the Qinghai–Tibet Expressway and subsequent access routes into Tibet.