Traffic accidents, especially those in rural areas, have been undeniably one of the critical issues in Thailand. Evaluation of road safety level should rely on a systematic approach so that project ranking and budgeting can be properly executed with valid supporting information. This paper focuses mainly on engineering components of rural road safety, with the key objective to demonstrate the development of the road safety index, a quantitative index representing the level of road safety on rural roads in Thailand. The developed index considers various roadway elements, for example, roadway geometry, traffic signs, road furniture, and pavement condition. These highway engineering components are under direct jurisdiction of the highway infrastructure development cluster of the Ministry of Transport. The road safety index will be of usefulness not only for identifying high-risk roads but also for selecting appropriate road safety improvement programs. The present paper also details the application of the developed index through a case study of applying the road safety index to rural roads in Thailand, which are maintained by the Department of Rural Roads, Ministry of Transport. In addition, the integration of the road safety index into a larger framework, the rural road safety management system, will be described.