as a heuristic tool that can help policy makers examine the dimensions that should be taken into account when assessing place-based policies. For transport corridors, it is critical to understand the mechanisms through which the corridor may bring about change (quantity effects) and look beyond immediate or direct effects of the transport corridor to induced changes in private sector behavior throughout the economy. It is also important to attribute value changes accurately, essentially by thinking clearly about opportunity costs, the value of resources in alternative uses, and the market failures and inefficiencies that motivate the policy intervention. In the context of special economic zones, the following factors are important in understanding differences in performance: geographic location, reliable infrastructure, connections with local universities, and high-skill exports. While some interventions such as SEZs are often spatially distant from the built-up area of existing cities, their viability often depends on linkages with cities. Further, poorly located SEZs tend to aggravate fiscal risks for the municipalities on which they depend. Efforts to leverage complementarities between transport, land use, and housing policies are central to managing urban congestion. Piecemeal interventions tend to exacerbate congestion and fragment urban labor markets, further dampening the potential for agglomeration economies.
Annex 7A. Using Spatial General Equilibrium Models to Quantify the Indirect Effects of Highway Corridors in Africa Two recent studies use spatial general equilibrium models to quantify the indirect effects of highways corridors in West Africa and the Horn of Africa. Lebrand (2021) reviews the potential benefits of developing the Dakar-Lagos highway corridor between Dakar, Senegal, and Lagos, Nigeria, which crosses most coastal West African countries. The Dakar-Lagos corridor is part of the Trans–West African Coastal Highway, which links 12 West African coastal nations, from Mauritania in the northwest to Nigeria in the east, as well as two landlocked countries, Burkina Faso and Mali, with feeder roads. It mostly follows the coastline along more than 4,000 kilometers and connects the capitals of the 14 countries. The expected economic impacts of the Lagos-Dakar highway corridor would differ across countries. Along the northern section between Dakar and Abidjan, Côte d’Ivoire, road improvements are expected to enable the transit of agricultural production from Senegal to neighboring countries The Gambia, Guinea Bissau, and Guinea. In Liberia, the corridor aims to reduce the isolation of rural areas and improve integration at the Côte d’Ivoire border. The southern part of the corridor between Abidjan and Lagos connects the most densely populated and economically active parts of the subregion and interconnects with a rail network, major ports,
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