In this paper, we present a new hardware-in-the-loop traffic signal simulation framework, which is referred to as HILS-NG. With this proposed framework, pioneering traffic signal control strategies proposed by researchers can be separated from traffic simulation engine while interacting with simulations as independent applications via standard traffic control communication. The advantages of this new framework include the following. First, pioneering traffic signal logic only needs to be programmed once for simulation, and the same code can be deployed to the field with minimal porting efforts. Second, control algorithms are hosted in supplemental hardened single-board computers (SBCs) do not require replacing traffic signal controllers in the field; therefore, the proposed framework will not compromise the existing signal safety protections in signal cabinets, such as phase conflict monitor. We expect that this new framework will greatly facilitate the prototyping and field tests of new traffic signal control strategies for scholars and practitioners. To further demonstrate the potential of this new framework, in the second part of this paper, we utilize an industrial communication standard for traffic signal controllers in North America, i.e., the National Transportation Communications for ITS Protocol (NTCIP), to set up real-time communications with a full-scale traffic signal emulator in simulation and then develop and evaluate a set of innovative e signal control strategies. A set of new signal control strategies is also presented to demonstrate how to design control functions and the corresponding NTCIP communication stacks.

Disaster response to manmade and natural events involves the quick evacuation of the affected population to safer areas. Given the potential for large-scale loss of life and property, there is a need for effective emergency strategies to mitigate the adverse effects of these disasters. Most existing evacuation traffic management strategies focus on increasing network capacity along the evacuation direction such as contraflow lanes, but other information or routing strategies have not been fully explored. Optimal routing strategies can be presented to evacuees as recommended routes. Advising evacuees that take system-optimal routes help balance the distribution of evacuation flows among multiple evacuation routes. However, a critical aspect in evaluating the effectiveness of such strategies is to properly account for the possible evacuation route-choice behavior. This study analyzed the situation in which evacuees are given a set of system-optimal paths; evacuees choose their evacuation routes, following a certain route-choice behavior (rational, panic, etc.). Discussions focus on the extent to which the routing effectiveness can be properly estimated, subject to the route-choice behavior. This paper further proposes a behavior-robust feedback information routing (FIR) strategy to further improve system performance. The FIR is based on the concept of closed-loop control that reacts to the system state and updates the advised routes. The FIR that targets the system-optimal routing strategy has been shown to be effective and robust for real-time evacuation traffic management.

Abstract When a vehicle on a scheduled trip breaks down, one or more vehicles need to be rescheduled to serve the customers on that trip with minimum operating and delay costs. The problem of reassigning vehicles in real‐time to this cut trip as well as to other scheduled trips with given starting and ending times, is referred to as the vehicle rescheduling problem (VRSP). This paper considers modeling, algorithmic, and computational aspects of the single‐depot VRSP. The paper formulates a model for this problem and develops several fast algorithms to solve it, including parallel synchronous auction algorithms. The concept of the common feasible network (CFN) is introduced to find a good set of initial “prices” for speeding up the auction algorithm. Computational experiments on randomly generated problems are described. Computational results show that, for small problems, all of the developed algorithms demonstrate very good computational performances. For large problems, parallel CFN‐based auction algorithms provide the optimal solution with much smaller computation times. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(3), 211–229 2007

Microsimulation models are normally used to evaluate traffic-adaptive signal control systems. This paper develops an analytical approach for this evaluation based on queuing models. In particular, a queuing model is developed for a simplified adaptive control strategy that is based on rolling horizon scheme, in which a signal serves two movements alternatively. In this strategy, the first movement is served until the queue dissipates, then the second movement is served until the queue dissipates, then the signal goes back to serving the first movement, and this cyclic process repeats. A numerical algorithm is developed in a stochastic context to compute steady-state performance measures such as average delays and expected queue lengths. These results are compared with simulation-based results, and indeed, the analytically derived numerical method predicts well the simulation results

A limitation of most traditional methods of traffic data collection is that they rely on techniques that are strictly local in nature. Aerial imagery sensors can provide sufficient resolution to sense vehicle locations and movements across broader spatial and temporal scales. Digital imagery, global positioning systems, and automated image processing can be used to improve the spatial coverage, accuracy and cost-effectiveness of the data collection and reduction. In this paper, an approach for collecting and analyzing aerial imagery is given. To illustrate the value of the imagery, the paper outlines methods to generate estimates of speeds, travel times, densities, and queueing delays.

A concurrent modeling approach for solving production control problems is presented. The approach concentrates on developing a common model formulation to represent the problem for different purposes. A unique mathematical representation is used that can support a hierarchically structured control system for production scheduling problems. The appropriate representations are obtained at each level of the hierarchy by using Lagrangian relaxations. The model can also be used within each level of the hierarchy to develop fast and efficient heuristics for detailed scheduling.>

Abstract This paper formulates and classifies some multicommodity flow problems (MFP) on “stochastic networks.” Here, the arc attributes are not necessarily deterministic, but, rather, are allowed to be probabilistic. Some special cases of the stochastic multicommodity flow problems (SMFP) are considered where the resultant formulations are solvable by existing algorithms for MFP. Specifically, we consider the following problems: SMFP‐FLOW INDEPENDENT, where the arc travel attributes are random but not dependent on the flows in the network, and SMFP‐FLOW DEPENDENT, where the stochasticity of arc travel attributes is either due to random demands or due to arc free‐flow travel attributes being probabilistic. The scenario where the cost function c(w), of travel attribute w, is linear is fully explored‐for both the above problems. Also, some special cases of the problems are studied when c(w) is exponential or quadratic in w. As an illustrative application, some traffic assignment problems on stochastic networks are formulated and solved as SMFPs.

An approach that allows in-process machine-loading through magazine setups, and concurrently routes and sequences the jobs on the versatile machines, is presented. To illustrate the concurrent approach, a specific two-versatile-machine flowshop scheduling problem, referred to as 2-VFSP, is defined and studied in detail. Theoretical results show that the optimal schedule for 2-VFSP need not have more than two in-process magazine setups, giving rise to the three possible scheduling configurations. Further, it is proven that obtaining the optimal schedule is an NP-complete problem. A heuristic is developed and tested on sets of random joblists, with different setup times corresponding to varying degrees of machine versatility. Results indicate that schedules which incorporate in-process magazine setup(s) may be more desirable when the setup time is small. Thus the use of concurrent scheduling approach which allows in-process magazine setups may be especially useful for systems with very versatile machines.>

The types of automated operations a flexible manufacturing machine can perform depend on the tools available in its tool magazine. Since magazine setups are usually non-automated, the time and effort cost for such setups is not negligible for scheduling purposes. This paper considers the scheduling problem of minimizing the completion time of a joblist, where each job requires two operations with the same precedence order, on two machines each capable of performing both operation types but requiring a magazine setup if one operation type is to be followed by the other. The paper shows that in an optimal schedule, at most one setup is required on each of the two machines. Heuristics are developed for scheduling a joblist on this two-machine flexible manufacturing system (FMS). For an empirical evaluation, randomly generated joblists are scheduled using these heuristics. As would be expected, schedules with zero setups are better when the setup time is large; for small setup times schedules with one and two setups become competitive.

Abstract Locating a single facility (the 1‐median problem) on a deterministic tree network is very efficiently solved by Goldman's algorithm. This paper explores the possibility of efficiently solving the 2‐median problem for both deterministic and probabilistic tree networks. Interesting properties (Theorems 1–4) are derived that relate the location of 1‐median to the location of pairs of 2‐medians. Two simple algorithms, the “Improved Link‐Deletion” algorithm for the deterministic case and the “Selective Enumeration” algorithm for the probabilistic case, are presented which somewhat improve existing methods to determine 2‐medians on tree networks.

An auditory display in a dual-axis compensatory tracking task was studied. Subjects were presented concurrently with the primary task of controlling a second-order plant and the secondary task of controlling a first-order plant. The plant errors for the two tasks were shown on separate visual displays. An auditory display, whose output varied in frequency and volume with the error, was used to supplement the secondary task in half of the runs. To study the effects of the auditory display, two performance measures were obtained: 1) the integral of the squared error (ISE) and 2) the describing functions of the human operator. Statistical analysis of the ISE measures indicated that when the secondary task was supplemented with an auditory display, there was a significant improvement in performance on the secondary task. The performance on the primary task improved on the average, but not significantly. The variances of the ISE values decreased for both the tasks, indicating a more consistent behavior with the auditory display. The describing function analysis showed that supplementing the secondary task with the auditory display increased the low frequency gain of the human operator for this task. The describing functions for the primary task did not show any apparent changes.