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• 1. [Article] Model for Network Assignment Problem of Capacitated Freight with Disruptions

  A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability ...

  Citation × Citation Citation Abstract Copy Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Close

• 2. [Article] Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies

  Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation ...

  Citation × Citation Citation Abstract Copy Title: Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies Author: Bigazzi, Alexander Y., Figliozzi, Miguel Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Title: Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies Author: Bigazzi, Alexander Y., Figliozzi, Miguel Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Close

• 3. [Article] Vehicle Routing Problem for Emissions Minimization

  Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of ...

  Citation × Citation Citation Abstract Copy Title: Vehicle Routing Problem for Emissions Minimization Author: Figliozzi, Miguel Year: 2010 Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of a routing problem despite the growth in use and impact of commercial vehicles. In the capacitated vehicle routing problem (VRP) with time windows, it is traditionally assumed that carriers minimize the number of vehicles as a primary objective and distance traveled as a secondary objective without violating time windows, route durations, or capacity constraints. New research focuses on a different problem: the minimization of emissions and fuel consumption as the primary or secondary objective. This creates the emissions VRP (EVRP). A formulation and solution approaches for the EVRP are presented. Decision variables and properties are stated and discussed. Results obtained with a proposed EVRP solution approach for different levels of congestion are compared and analyzed. Title: Vehicle Routing Problem for Emissions Minimization Author: Figliozzi, Miguel Year: 2010 Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of a routing problem despite the growth in use and impact of commercial vehicles. In the capacitated vehicle routing problem (VRP) with time windows, it is traditionally assumed that carriers minimize the number of vehicles as a primary objective and distance traveled as a secondary objective without violating time windows, route durations, or capacity constraints. New research focuses on a different problem: the minimization of emissions and fuel consumption as the primary or secondary objective. This creates the emissions VRP (EVRP). A formulation and solution approaches for the EVRP are presented. Decision variables and properties are stated and discussed. Results obtained with a proposed EVRP solution approach for different levels of congestion are compared and analyzed. Close

• 4. [Article] Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace

  Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are ...

  Citation × Citation Citation Abstract Copy Title: Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace Author: Figliozzi, Miguel, Mahmassani, Hani, Jaillet, Patrick Year: 2003 Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers' strategies in a transportation auction market place is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the performance of these market places under different carrier bidding strategies are discussed. A simulation framework is used to explore the complex engineering and economic processes and issues that arise in a transportation marketplace and that are difficult to explore by using standard analytical or statistical tools. Some results and the overall simulation framework are also discussed. Title: Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace Author: Figliozzi, Miguel, Mahmassani, Hani, Jaillet, Patrick Year: 2003 Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers' strategies in a transportation auction market place is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the performance of these market places under different carrier bidding strategies are discussed. A simulation framework is used to explore the complex engineering and economic processes and issues that arise in a transportation marketplace and that are difficult to explore by using standard analytical or statistical tools. Some results and the overall simulation framework are also discussed. Close

• 5. [Article] Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints

  This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and ...

  Citation × Citation Citation Abstract Copy Title: Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints Author: Figliozzi, Miguel Year: 2009 This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and planning analysis of transportation and logistics problems. Using asymptotic properties of vehicle routing problems and the average probability of successfully sequencing a customer with time windows a new expression to estimate VRP distances is developed. The increase in the number of routes when time constraints are added is modeled probabilistically. This paper introduces the concept of the average probability of successfully sequencing a customer with time windows. It is proven that this average probability is a unique characteristic of a vehicle routing problem. The approximation proposed is tested in instances with different customer spatial distributions, depot locations and number of customers. Regression results indicate that the proposed approximation is not only intuitive but also predicts the average length of VRP problems with a high level of accuracy. Title: Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints Author: Figliozzi, Miguel Year: 2009 This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and planning analysis of transportation and logistics problems. Using asymptotic properties of vehicle routing problems and the average probability of successfully sequencing a customer with time windows a new expression to estimate VRP distances is developed. The increase in the number of routes when time constraints are added is modeled probabilistically. This paper introduces the concept of the average probability of successfully sequencing a customer with time windows. It is proven that this average probability is a unique characteristic of a vehicle routing problem. The approximation proposed is tested in instances with different customer spatial distributions, depot locations and number of customers. Regression results indicate that the proposed approximation is not only intuitive but also predicts the average length of VRP problems with a high level of accuracy. Close