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  • Mobility and traffic research  (5)
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  • Mobility and traffic research  (5)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2345, No. 1 ( 2013-01), p. 109-116
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2345, No. 1 ( 2013-01), p. 109-116
    Abstract: This study examined the North American Industrial Classification System–based manufacturing industry (NAICS 31-33) from 1997 to 2010 in a cost-based framework. First, both profit and production function models were constructed and estimated for the U.S. manufacturing industry at the state level to allow for spatial spillovers and interactions. A model based on profit and production provided an alternative approach to the dual-cost function. Elasticities associated with infrastructure investment and industry total costs were determined by the inclusion of data on transportation infrastructure spending. Results of the spatial econometric models and the computed elasticities were then delivered in a geographic information system.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: In this paper, we examine the practical problem of minimizing the delay in traffic networks that are controlled at each intersection independently, without a centralized supervisory computer and with limited communication bandwidth. We find that existing learning algorithms have lackluster performance or are too computationally complex to be implemented in the field. Instead, we introduce a simple yet efficient and effective approach using multi-agent reinforcement learning (MARL) that applies the Deep Q-Network (DQN) learning algorithm in a fully decentralized setting. First, we decouple the DQN into per-intersection Q-networks and then transmit the output of each Q-network’s hidden layer to its intersection neighbors. We show that our method is computationally efficient compared with other MARL methods, with minimal additional overhead compared with a naive isolated learning approach with no communication. This property enables our method to be implemented in real-world scenarios with less computation power. Finally, we conduct experiments for both synthetic and real-world scenarios and show that our method achieves better performance in minimizing intersection delay than other methods.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: Over the last decade, there has been rising interest in automated driving systems and adaptive cruise control (ACC). Controllers based on reinforcement learning (RL) are particularly promising for autonomous driving, being able to optimize a combination of criteria such as efficiency, stability, and comfort. However, RL-based controllers typically offer no safety guarantees. In this paper, we propose SECRM (the Safe, Efficient, and Comfortable RL-based car-following Model) for autonomous car-following that balances traffic efficiency maximization and jerk minimization, subject to a hard analytic safety constraint on acceleration. The acceleration constraint is derived from the criterion that the follower vehicle must have sufficient headway to be able to avoid a crash if the leader vehicle brakes suddenly. We critique safety criteria based on the time-to-collision (TTC) threshold (commonly used for RL controllers), and confirm in simulator experiments that a representative previous TTC-threshold-based RL autonomous-vehicle controller may crash (in both training and testing). In contrast, we verify that our controller SECRM is safe, in training scenarios with a wide range of leader behaviors, and in both regular-driving and emergency-braking test scenarios. We find that SECRM compares favorably in efficiency, comfort, and speed-following to both classical (non-learned) car-following controllers (intelligent driver model, Shladover, Gipps) and a representative RL-based car-following controller.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2157, No. 1 ( 2010-01), p. 1-10
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2157, No. 1 ( 2010-01), p. 1-10
    Abstract: Random utility models customarily assume strict independence of individual decision makers. Evidence of crowding, peer pressure, herd behavior, and other instances of spontaneous discrete choice coordination indicates that decision makers interact and thus affect choices made by others. Socially influenced individual choices become biased toward either agreeing with or contradicting the choices made by peers. Because many social interdependencies are spatial, a basic spatial discrete choice model was obtained by extending random utility theory to discrete choices made by heterogeneous spatially dependent individuals. Although interdependencies are unobserved, the model permits the study of behavioral biases arising from spatial interdependencies. The spatial discrete choice model is shown to address the effects of behavioral biases on conditional choice probabilities, the marginal effects of exogenous variables on revealed preferences, and the spatial patterns of discrete choices. A pseudo maximum likelihood (PML) estimator for the model is developed, and closed-form expressions for conditional choice probability estimates are derived. The PML estimator is shown to be consistent and computationally feasible for large spatial data sets. Simulated data were used to illustrate the performance of the PML estimator for the spatial discrete choice model.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
    detail.hit.zdb_id: 2403378-9
    Library Location Call Number Volume/Issue/Year Availability
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 7 ( 2023-07), p. 340-358
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 7 ( 2023-07), p. 340-358
    Abstract: Adaptive cruise control (ACC) systems are increasingly offered in new vehicles in the market today, and they form a core building block for future full autonomous driving. ACC systems allow vehicles to maintain a desired headway to a leading vehicle automatically. Recent research demonstrates that (1) shorter headways lead to higher throughput, and (2) the effective use of ACC can improve traffic flow by adapting the desired time headway in response to changing traffic conditions. In this paper we show that, although shorter headways result in higher capacity, flow breakdown still occurs if traffic densities at bottlenecks are allowed to exceed the critical density. Therefore, dynamic traffic control near bottlenecks is still necessary to avoid bottleneck activation and capacity loss. We propose an adaptive reinforcement learning (RL) headway controller that uses ACC headways to optimize traffic flow and minimize delay. Based on state measurements, the controller dynamically assigns an optimal headway value for each freeway section within a control cycle. In a freeway simulation example, we first demonstrate that different nondynamic headway assignment strategies failed to avoid congestion and traffic breakdown. We then present a dynamic headway control strategy based on deep reinforcement learning (DRL) that adapts the desired headway according to the changing traffic conditions on both the freeway and the ramp to effectively maximize traffic flow and minimize system delay. We quantitatively demonstrate that our DRL dynamic headway control strategy improved traffic and reduced system delay by up to 57% compared with the examined nondynamic headways.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
    Library Location Call Number Volume/Issue/Year Availability
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