Formulation and solution algorithms for highway infrastructure maintenance optimisation with work-shift and overtime limit constraints

This paper deals with the issue of highway infrastructure maintenance which is indirectly related to city logistics since for efficient city logistics, operation highway infrastructure must be kept in good functioning condition. Roadside appurtenances such as guardrails, signs, and luminaries perform major functions in the utilisation and overall safety of the highway throughout their life-cycle. As a consequence, their maintenance is very critical to maximise life of the highway and promote safe mobility. However, budget and personnel constraints make it difficult for urban cities and other local government authorities to meet highway maintenance inspection challenges. As a result, they must prioritize as well as maximise the use of manpower to keep pace with the inspection demands maintaining their highway assets. Highway assets such as guardrails, signs and luminaries become secondary priorities and are often neglected, resulting in poor maintenance and corresponding reduction in their life-expectancy. Consequently, local authorities must find the right balance between available resources and efficient use of time in order to achieve their highway maintenance objectives. In this paper, a cost minimization problem considering work-shift and overtime constraints is presented. An algorithm using Floyd's shortest path method is developed to optimize the time and paths for efficient inspection of highway assets. An illustrative example from real-life applications is presented and discussed.