We develop a simple approach for modeling schedule delay in a deterministic setting based on user equilibrium concepts and deterministic queuing theory. Several cases of peak period commuting or travel to scheduled events (such as sporting events) are analyzed as illustrations. The results demonstrate the importance of schedule delay for departure time decisions. The analysis framework can be used to improve the transportation planning and evaluation process, and we have identified several related research issues which could provide further insights into departure time decisions and the performance of transportation systems.

This study estimates the life cycle water consumption and wastewater generation impacts of a Marcellus shale gas well from its construction to end of life. Direct water consumption at the well site was assessed by analysis of data from approximately 500 individual well completion reports collected in 2010 by the Pennsylvania Department of Conservation and Natural Resources. Indirect water consumption for supply chain production at each life cycle stage of the well was estimated using the economic input–output life cycle assessment (EIO-LCA) method. Life cycle direct and indirect water quality pollution impacts were assessed and compared using the tool for the reduction and assessment of chemical and other environmental impacts (TRACI). Wastewater treatment cost was proposed as an additional indicator for water quality pollution impacts from shale gas well wastewater. Four water management scenarios for Marcellus shale well wastewater were assessed: current conditions in Pennsylvania; complete discharge; direct reuse and desalination; and complete desalination. The results show that under the current conditions, an average Marcellus shale gas well consumes 20 000 m³ (with a range from 6700 to 33 000 m³) of freshwater per well over its life cycle excluding final gas utilization, with 65% direct water consumption at the well site and 35% indirect water consumption across the supply chain production. If all flowback and produced water is released into the environment without treatment, direct wastewater from a Marcellus shale gas well is estimated to have 300–3000 kg N-eq eutrophication potential, 900–23 000 kg 2,4D-eq freshwater ecotoxicity potential, 0–370 kg benzene-eq carcinogenic potential, and 2800–71 000 MT toluene-eq noncarcinogenic potential. The potential toxicity of the chemicals in the wastewater from the well site exceeds those associated with supply chain production, except for carcinogenic effects. If all the Marcellus shale well wastewater is treated to surface discharge standards by desalination, $59 000–270 000 per well would be required. The life cycle study results indicate that when gas end use is not considered hydraulic fracturing is the largest contributor to the life cycle water impacts of a Marcellus shale gas well.

Product take-back of consumer products is generally expensive, especially reverse logistics. In the take-back program for power tools in Germany, costs exceed revenues for recycling power tools. Systematic analysis of take-back alternatives can make take-back policies more attractive. For example, an alternative take-back system for power tools would combine profitable remanufacturing and unprofitable materials recycling. The profit from remanufacturing could cover the loss from recycling as well as the costs of reverse logistics, allowing the manufacturer a profit. Remanufacturing requires a continuous flow of returned postconsumer products. By buying back end-of-life products, firms could control the flow of returned products. We developed a model that allows us to determine the optimal amount to spend on buy-back and the optimal unit cost of reverse logistics. We can use the latter to select a suitable reverse-logistics system for end-of-life products. We apply our model to the remanufacturing take-back concept for power tools, using empirical data on the current take-back program.