The global infrastructure gap has continually widened over the last few decades. Industry reports and academic publications suggest that, in terms of road infrastructure, both advanced and developing economies have not paid sufficient attention to modernize their infrastructure assets. A wider road infrastructure gap signifies that highway conditions have declined because governments have not had enough resources for maintenance and rehabilitation. In the same way, it also indicates that congestion levels have grown and the level of service in most road networks has dropped because public agencies have not had sufficient funds to generate new highways and expand existing corridors. This dissertation, therefore, provided insights into the difficulties associated with improving the existing highway assets and the barriers related to expanding the current roadway capacity through public-private partnerships (PPPs). The research involved three interdependent studies. In the first study, I examined the continuous deterioration of the US highway system through a system dynamics model, which focused on the dynamics of capital investments and maintenance expenditures in the US road infrastructure. The results confirmed that the American highway system is currently stuck in a capability trap. This makes it difficult for the system to improve at the rates required by the country's economic growth. In my second investigation, my attention shifted toward the governance challenges related to building new roads and expanding highway capacity through PPPs. I developed a systems map of governance variables informed by past-published evidence from actual projects. By specifically examining the shaping phase of public-private initiatives, the work uncovered the effects of feedback relationships and interdependencies on PPP feasibility. This offered insights about the relationship between governance mechanisms and successful PPP development. In the third study, I utilized variables and relationships identified in my second investigation to develop a management flight simulator in order to better explain governance difficulties in the procurement phase of PPP projects. The simulator was implemented during an educational exercise with graduate students of civil engineering. By doing so, I confirmed that the simulator has the potential to increase our understanding of PPP procurement processes. Results indicated that the simulation tool was a suitable instrument to explain how government capacity, project uncertainty, and technical complexity influence PPP tendering. Overall, my findings across the three studies illustrate different means to understand why closing the global road infrastructure gap is challenging. Together, the three inquiries indicate that examining the road infrastructure sector as a socio-technical system contributes to improve our understanding of the expenditure dynamics related to existing assets and to enhance our comprehension of the governance challenges associated with developing new roads. / Ph. D. / Over the last decades, the global infrastructure gap has continually expanded. In the road infrastructure sector, governments around the world have failed to meet the growing societal and economic demands for additional infrastructure investments. This suggests that highway conditions have declined because there are not enough resources to improve the existing roads and develop new highways. As a result, the size and quality of global road network keep deteriorating annually. This dissertation provided insights into the difficulties related to enhancing the quality conditions of the existing road network and the problems associated with increasing roadway capacity through public-private partnerships (PPPs). The research was conducted through three interdependent studies. In the first study, I developed a simulation model in order to understand the continuous deterioration of the US highway system. I concluded that the US government has been unable to achieve sustained improvements in the system because of prioritizing rehabilitation over preventive maintenance. In my second investigation, I conducted a literature review focused on analyzing governance-related concepts in PPP projects. I created a systems map that helps to understand how governance variables influence failure and success in the shaping phase of public-private agreements. In the third study, I developed an educational tool focused on explaining some of the challenges of conducting procurement processes in PPPs. This tool proved to be effective in terms of illustrating how government capacity, project uncertainty, and technical complexity influence PPP tendering. Overall, the three studies offer a socio-technical perspective of why closing the global road infrastructure gap is challenging. Together, they contribute to improve our understanding of the difficulties associated with enhancing the conditions of the current road network and developing new roads through PPPs.