This paper explores the relationship between hubbing activities and flight delays in the United States from an airline-specific network perspective. Airline hubbing is measured with the Hubbing Concentration Index. We estimate the impact of hubbing behavior on delays, using three measures of...

Woody biomass harvested from old-growth forests results in a significant “carbon debt” when used as a feedstock for transportation fuel. This is because previously stored forest carbon is released to the atmosphere as CO2. The debt is eventually repaid provided that the life cycle CO2...

We quantify energy return on energy investment (EROI) as one metric for the sustainability of alternative jet fuel production. Lifecycle energy requirements are calculated and subsequently used for calculating three EROI variants. EROI1 is defined as the ratio of energy in fuel output to...

This paper quantifies the technical efficiency of German public bus transport companies and discusses main factors influencing their performance, using a stochastic production frontier approach. We test for the efficiency impact of ownership structure, competitive tendering, and potential...