Paper Title
Prioritization of National Highways for Climate Adaptation Investment Planning in Thailand

Abstract
Climate change puts transportation at risk. Natural disasters caused by climate change destroy transport infrastructure. In Thailand, floods are the most destructive disasters on the transport infrastructure where road transport is the mostly used. To reduce the impact of climate change, adaptation will be implemented. Adaptation is a concept that can effectively address the impact of climate change. However, the investment in adaptation is quite costly. In countries with limited budgets, planning should be controlled to focus on, what is significant and worth the investment which can be achieved through prioritization. Prioritizing can help with analysis and planning, which can lower the cost.In this study, prioritization methodology is divided into three parts. The first part will be collected all the national highways in Thailand and defined the criteria. The criteria consist of the road that was affected by flood, the road that is along with the river/canal, and the road is around the Kaem Ling project. The second part is screening the road with criteria. The final part is the prioritization. This part classifies the road based on their importance by using International Roughness Index (IRI), the urgency by using Vehicle-Kilometer (VK) and weighting to classify the road. As the result, there are 317roads that was affected by flood, 260 roads that are along the river or canal, and 36 roads that located near Kaem Ling Project. There are only two roads which are the highest IRI range, 112 roads that are the highest VK range. In the part of prioritization. There are 111 roads identified as very important resulting in total distance of 804.11 km. These results highlight the most important roads. The majority of the roads and distances that can be prioritized are from road start with 3. Mostly, they are located in central and eastern region, which are frequent flood, roads are along with the river/canal, and roads are around Kaem Ling project. In addition, using IRI and VK can show with poor surface condition which they need to be repaired, and relatively high travel volume which tell the importance of roads for traveling. It can be utilized to plan and decide the investment of the national highways for the highest efficiency. Keywords - Climate Adaptation Investment, Transportation, Prioritization, International Roughness Index, Vehicle-Kilometer.