Research Topics
This group's research activities focus on Transportation Planning and Logistics Systems. Main emphasis is on Resilient and Economic City Logistics, Transportation Asset Management, and Sustainable Infrastructure Development. Robust models are developed to realistically represent complex problems in transportation systems both in tactical and operational levels. Further, effective and practical solution techniques to the developed models are provided with the objective of improving planning, design, and operation of such complex systems at various spatial and temporal scales.
1. Resilient and Economic City Logistics
2. Transportation Asset Management
3. Sustainable Infrastructure Development
1. Resilient and Economic City Logistics
We develop mathematical models and solution methods to optimize service truck routing, resource planning, and transportation network design in large-scale urban areas. Routing models for service trucks operations are formulated to simultaneously optimize the total truck travel time, cycle time balance between trucks, and resource replenishment location and timing. These routing models address time-of-day congestion and traffic control delays as well. The random nature of demand often influences traffic service reliability and causes safety concerns. To address the impact of fleet size and operational uncertainty on service reliability, we develop a set of models and solution methodologies for dynamic fleet management in a decision-making process under service disruptions and uncertain demand. Besides, routing of service trucks can be affected by network design, e.g., number and location of satellite facilities that trucks visit during maintenance operations. Therefore, we propose integrated mathematical models to determine the optimum number and location of resource replenishment facilities. We aim to minimize the total cost for infrastructure investments as well as transportation on urban roadways (including both public travel and service truck routing). These models and solution techniques in this area are also suitable for a number of application contexts that simultaneously involve network traffic equilibrium, truck routing, infrastructure expansion, and facility location choices (which determine the origin/destination of multi-commodity flow).
The number and location of depots and resource replenishment facilities significantly affect the route plan and level of service. This requires resilient planning and forecasting foundation at (i) strategic level, such as simultaneous location design and routing under facility disruption scenarios and (ii) operational level, by modeling dynamic and real-time operation of service trucks under time-variant traffic flow information, driver attendance time, and departure times to optimize routing policies. We model and simulate the evolving dynamics of such complex systems.
2. Transportation Asset Management
We develop robust models for asset management policies to provide stakeholders with reliable planning tools on operation, maintenance, and management of their systems. One interesting example is determining the optimal utilization levels for highway fleet equipment assets, as they are critical components for delivery of agency programs, projects, and services and contribute to a major part of capital investments. Our focus is on developing reliable models to determine optimal criteria for utilizing different classes of equipment assets including the optimal fleet size and composition to maintain the level of service for state level operations and timing, number, and location of fleet asset assignments for a broad range of situations.
The methodologies that we propose aim to minimize the total cost including the capital investments, cost of alternatives to agency ownership of each asset, and cost of maintenance and operations, while satisfying the equipment needs of the agencies. This provides the highway agencies with a timely and cost-effective decision-making procedure regarding the management of their assets. We will continue developing optimization algorithms for management of different transportation assets including pavement, bridges, transit systems, and traffic signal systems.
3. Sustainable Infrastructure Development
We study the development of emerging industries and its impact on urban and regional infrastructures. In particular, we focus on the integrated planning of supply chain networks, freight logistics, and multi-modal transportation infrastructure expansion for new industry developments, where the optimum number and location of facilities, optimal freight shipments, and possible highway/railroad capacity expansion are jointly determined. We develop efficient customized solution frameworks to solve these optimization models.
Furthermore, establishment of industry facilities often induces heavy freight vehicle traffic and exacerbates congestion and pavement deterioration in the neighboring highway network. This depicts an inter-relationship between human-based activities and infrastructure facilities that contribute to significant costs for public and private sectors. Hence, during facility location planning and land use developments, it is important to take into account the inter-dependencies among routing of freight vehicles, the impact on public traffic, as well as the planning of pavement rehabilitation. We develop formulations and solution methodologies for joint optimization of supply chain network design and highway pavement infrastructure rehabilitation plan under traffic equilibrium. The objective is to minimize the total cost due to facility investment, transportation delay, and infrastructure life-cycle costs.
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