# **1 Introduction**

In recent decades, billions of dollars have been spent on road projects in conflict-affected areas. Such investments are often motivated by a combination of donor objectives, which may include access to resources, economic development, stabilization, and state-building. While there is a growing body of literature around the impact of investments in transport infrastructure on economic development in fragile states (Ali et al. 2015; Berg et al. 2017; Damania et al. 2018), there is little evidence that transport infrastructure also improves stability in conflict-affected countries (Bachmann and Schouten 2018; Schouten et al. 2022).

This paper addresses this gap by analyzing the impact of road rehabilitation projects on violence in the Democratic Republic of Congo (DRC). The DRC is an ideal setting to explore the relationships between roads and violence. Since 1997, it has been home to one of the most protracted humanitarian crises and complex conflicts in the world and has a road network that ‘is about 152,400 kilometers long but, for a large part, it only exists on maps’ (World Bank 2017). Concomitantly, the DRC has been subjected to sustained reconstruction and stabilization efforts by the international community, involving large investments in its road network. We, therefore, ask the following question: what effect, if any, did these investments in the road network have on violence in the DRC? We explore the impact of road investments on violence through a longitudinal study, monitoring conflict incidence before, during, and after road rehabilitation, comparing levels of violence to areas where no roads were rehabilitated. We are also interested in how long the putative effects of roadworks on violence lasted: while the theories of change of road projects assume ‘forever impacts’, previous research suggests that rehabilitated roads rapidly deteriorate again, given a lack of maintenance (Bachmann and Schouten 2018; Schouten et al. 2022). Does the effect of road rehabilitation on violence wane as the road quality gradually decreases again?

We first assembled a new database of the main transport infrastructure projects that occurred in the DRC since the end of the Second Congo War in 2003. A comprehensive list of such projects did not exist. We collected project data (start and completion years, cost, location, and type of infrastructure) from multiple sources, including international donors and government agencies, to create a panel of geolocalized investments. Our final panel of large inter-city road investments includes 192 projects (see Appendix B).

To answer our first question, we estimated the causal impacts of road construction on conflicts. Establishing causal links is challenging because of the interaction of road projects and the activity of armed actors with other, often unobserved factors, such as conflict dynamics and economic activity. For instance, mining (a key economic activity in eastern DRC), outbreaks of violence, and road construction are all placed endogenously, often reacting to each other (cf. Luo et al. (2021)). We address this issue of causality between roads and conflicts in three ways. First, we show that road projects do not select into peaceful regions. This means that it is unlikely that armed violence generally forces road rehabilitation out of a conflict-affected region. Second, we use an identification strategy exploiting the fact that a road project crosses a 55km by 55km cell. Such localized treatment is unlikely to be related to local violence trends as the project completion is recorded at a higher level.

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