Climate change poses a critical threat to future development, particularly in areas where poverty is widespread and key assets such as infrastructure are underdeveloped for even current needs. The focus of this study includes ten geographically and economically diverse countries and the impact of 54 distinct AR4 Global Circulation Model (GCM) scenarios of future climate change on their existing road networks. The analysis is completed using a software tool which uses engineering and materials-based stressor-response functions to determine the impact of climate on maintenance, repair and construction. This study represents an update to a previous study conducted by the authors in 2011. The key updates include methodological advances, policy-oriented results presentation and the use of a new software tool developed by the authors. For nine out of ten countries in the study, pro-active adaptation measures result in lower fiscal costs and higher connectivity rates as early as 2025. The results through 2100 are presented and the costs of climate change present clear findings for these countries in terms of road maintenance, construction, and adaptation policy. In rural areas, particularly those in low-income countries, roads represent a lifeline for economic and agricultural livelihood, as well as a number of indirect benefits including access to healthcare, education, credit, political participation, and more. Roads may be sparse through geographic locations, making each road critical. Extreme events pose a costly hazard to roads in terms of degradation, necessary maintenance, and potential decrease in lifespan due to climatic impacts. Climate change poses costly impacts in terms of maintenance, repairs and lost connectivity; yet many of these impacts can be mitigated and avoided by pro-active adaptation measures. It is a crucial consideration for protecting current and future infrastructure investments and the economic, social, and other functions they serve. The Infrastructure Planning Support System (IPSS) is a software tool designed to quantify the impacts of both extreme events and incremental climatic changes on road infrastructure in any geographic location throughout the world. The system identifies the financial cost on a yearly basis through 2100 and allows users to compare proactive adaptation measures and reactive non-adaptation measures. IPSS compares a ‘no climate change’ scenario as a baseline to provide information on the ‘regret’ that may occur if a predicted outcome of climate change model does not manifest as projected. Infrastructure impacts are determined based on civil engineering materials research, field studies of actual impacts on roads and buildings, and additional data. These resources are combined into stressor-response equations which are implemented to provide specific cost estimates. Additionally, the program can be customized to a specific location where data is available on stressor-response impacts on the infrastructure elements being analyzed. This paper focuses on the methodology and application of the IPSS tool to countries representing a range of incomes including low-income, middle, and upper income countries. The IPSS tool is used to compare costs of adaptation and opportunity cost for each country. The results indicate that higher income countries face significant dollar costs due to the extensive road networks, with very high costs in Japan and Italy, in particular. Bolivia, Ethiopia, and Cameroon all show extremely high advantages to adaptation, yet the costs required to simply maintain existing networks are equivalent to funding equal to doubling or tripling the existing paved road inventory. These results can help policy makers at the national and international levels decide where and how to invest; and show that climate change represents a significant and urgent threat to transportation throughout the world. [ABSTRACT FROM AUTHOR]