"We examine two factors that might explain the extent of air traffic delays in the United States: network benefits due to hubbing and congestion externalities. Airline hubs enable passengers to cross-connect to many destinations, thus creating network benefits that increase in the number of markets served from the hub. Delays are the equilibrium outcome of a hub airline equating high marginal benefits from hubbing with the marginal cost of delays. Congestion externalities are created when airlines do not consider that adding flights may lead to increased delays for other air carriers. In this case, delays represent a market failure. Using data on all domestic flights by major US carriers from 1988-2000, we find that delays are increasing in hubbing activity at an airport and decreasing in market concentration but the hubbing effect dominates empirically. In addition, most delays due to hubbing actually accrue to the hub carrier, primarily because the hub carrier clusters its flights in short spans of time in order to maximize passenger interconnections. Non hub flights at hub airports operate with minimal additional travel time by avoiding the congested peak connecting times of the hub carrier. These results suggest that an optimal congestion tax would have a relatively small impact on air traffic delays since hub carriers already internalize most of the costs of hubbing and a tax that did not take the network benefits of hubbing into account could reduce social welfare"--National Bureau of Economic Research web site.

A comprehensive assessment of the challenges and opportunities created by worldwide access to this revolutionary technology.

In a world on the brink of a global recession caused by the COVID-19 global pandemic, the infrastructure efforts of today and tomorrow are more crucial than ever.For one, they are an indispensable countercyclical tool to mitigate the negative effects of the economic paralysis.But they also constitute a pivotal component for a country’s development, raising its competitiveness in the long term. That is why infrastructure will continue to play a critical role even when the pandemic crisis has been tamed.Rapid demographic growth, increasing urbanization, especially in developing countries, coupled with the ounting challenge posed by climate change, are trends that are not going to disappear with the virus.How to cope with these global, long-term trends? How to finance the increasing need for infrastructure? Which major international actors will take the lead? And what role will technology play in shaping the future of infrastructure?