Supply Chain-Consistent Threshold Accessibility Measures for Megaregion Economic Development

Supply chain networks (comprising buyer supplier connections) are integral to specialized manufacturing industries and are vital to the growth and development of megaregions. Transportation planning in megaregions requires an understanding of specialized industry sectors and the enhancement of the effects of the business network. Positive externalities and a competitive advantage can be augmented through transportation interventions. The directness of linkages and enhanced access between buyers and suppliers in any production network enables agglomeration economies, maximizes returns from investments, and can contribute to industry competitiveness. Physical transport networks are vital in ensuring directness in manufacturing sectors in which value chain segments are separated physically. This paper presents a framework for a behaviorally consistent directness measure explicitly linked to transportation infrastructure in megaregions, characterized by supply chains that enhance business networks. This index measures the enhanced accessibility provided by transportation by allowing systematic identification of links between buyers and suppliers in the value chain. The paper illustrates how the measure may be analyzed for an automobile manufacturing chain that is part of the southeastern Piedmont Atlantic megaregion.