in West Africa are evaluated. Better roads improve driving conditions but many hours remain lost around land borders and at final destinations for goods to reach the final customers. Reducing border frictions matters as goods have to transit up to 11 borders. Transit delays incurred by trucks crossing borders on their way are distinguished from final border delays incurred at destination.

Several findings emerge from the simulations. The upgrade of Dakar-Lagos regional road corridor brings sizable economic benefits relative to investment costs, with a Benefit-Cost Ratio estimated around 3. The economic benefits of road corridor upgrades are doubled and more widely spread when combined with measures to reduce current massive border delays. Income gains are larger for coastal western countries (+10-20%) than landlocked and eastern countries (+5-10%). The benefits are negligible for Nigeria, but large for small fragile states (GuineaBissau, Liberia, Sierra Leone). The projects benefit economic activity both along the corridors and, to a certain extent, more distant locations through geographic spillovers. The policy implication is that main road corridor investments are best complemented with measures to reduce border delays to amplify economic impact.

This paper relies on a well-developed tradition of spatial quantitative general-equilibrium models used to provide counterfactuals of transport and border investments. This paper uses the geographic granularity allowed by such models to estimate the sub-national, national and regional impacts of large transport and border investments. The model relies on previous work done by Redding (2016), and follows a growing literature on the spatial impacts of transport such as Fajgelbaum and Redding (2014) for Argentina, Donaldson (2018) for India, Lall and Lebrand (2020) and Bird et al. (2020) for the Belt and Road Initiative in Central Asia, Balboni (2020) for Vietnam, and Herrera Dappe and Lebrand (2019) and Herrera Dappe et al. (2021) for Bangladesh and India. We assume that large corridor investments will significantly improve driving speed. Major upgrades of regional roads are expected to improve road quality, reduce some traffic constraints (slow vehicles, density along the roads, congestion around gateways, etc), and therefore increase driving speed. The current driving speed is assumed to be low along most West African roads (Teravaninthorn and Raballand, 2009). The paper does not speak to the issues related to inefficiencies in the trucking sector (high mark-ups, poor fleet quality, intermediaries). Finally, the use of a structural model is motivated by missing data on domestic and cross-border trade in the region. Little is known about internal trade, formal trade per land border, and informal cross-border trade while informal trade is known to be ubiquitous in the region. The model generates trade linkages between districts and provinces that come from gravity properties between population centers. Given the geographic, cultural, ethnic, and language proximity of most countries, we can assume that these trade linkages are potentially significant, while not fully observed in national and international trade data.

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