Browsing by Author "Reddy, Radha"
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- An Intersection Management Protocol for Mixed Autonomous and Legacy VehiclesPublication . Reddy, Radha; Almeida, Luis; Tovar, EduardoAn important element in urban traffic management is the Intersection Management (IM) that deals with traffic lights signaling (either real or virtual). Intersections are vulnerable to traffic congestion and accidents. Therefore, this paper investigates a synchronous intersection management protocol for mixed autonomous and humandriven vehicles in the context of decentralized traffic management.
- CAP: Context-Aware Programming for Cyber Physical SystemsPublication . Gaur, Shashank; Almeida, Luís; Tovar, Eduardo; Reddy, RadhaContext-awareness is a prominently desired feature in computing systems. Smartphones, smart cards or tags, wearables, sensor nodes, and many other devices enable a system to compute context for different users and environment. With ever increasing advances in hardware for such devices, the interactions with users are increasing every day. This enables the collection of a large amount of data about users, systems, and physical environment. With such data available to be leveraged, context-awareness will soon become a necessity. Such type of data collection happens most frequently in sensing applications enabled by wireless sensor network (WSN) devices. This paper discusses the concept of context for sensing applications, specifically related to Cyber Physical Systems (CPS). The paper highlights key aspects of context and its definition. This paper proposes, to the best of the author's knowledge, the first programming approach to build context-aware applications for WSN-based CPS. This paper provides a proof of concept for a framework to detect, manage and deploy context-aware applications.
- Comparing the Ecological Footprint of Intersection Management Protocols for Human/Autonomous ScenariosPublication . Reddy, Radha; Almeida, Luis; Santos, Pedro M.; Tovar, EduardoThe design of Intelligent Intersection Management (IIM) schemes for fully Autonomous Vehicles (AVs) and mixed with Human-driven Vehicles (HVs) has focused mainly on throughput maximization and users’ safety. However, new IIM strategies should consider environmental factors and human health conditions in their design, given their impact on fuel wastage and emission of dangerous air pollutants. In this paper, we compare the ecological footprint of two IMM protocols that follow opposite paradigms in handling AVs and HVs with an internal combustion engine. We consider Round-Robin (RR) that favors the crossing of multiple consecutive cars from one road at a time and the recently proposed Synchronous Intersection Management Protocol (SIMP) that favors the crossing of multiple cars simultaneously, one from each road. Through experiments in the SUMO simulator, we observe that SIMP promotes more fluid traffic flows, causing traffic throughput to be up to 3.7 times faster and consume less fuel than the RR schemes, with similar results for vehicular emissions (PMx, NOx, CO, CO 2 , and HC).
- Complex Intersections with a Dedicated Road Lane per Crossing DirectionPublication . Reddy, Radha; Almeida, Luis; Santos, Pedro M.; Tovar, EduardoComplex intersections are often busier with a separate road lane per crossing direction, i.e., left, straight, and right. These intersections eliminate the diverging and merging conflicts; thus, vehicles only fall under crossing conflicts within intersections. However, the traditional way of serving vehicles from one road at a time increases traffic congestion and hinders performance. To address this issue, we extended the synchronous framework for complex intersections with a separate road lane per crossing direction, which was initially presented for single-lane and two-lane intersections in which roads are shared among vehicles with different crossing directions. We compare the performance of our synchronous framework against the traditional Round-Robin (RR) intersection management approach.
- Energy savings and emissions reduction of BEVs at an isolated complex intersectionPublication . Reddy, Radha; Almeida, Luis; Santos, Pedro Miguel; Kurunathan, Harrison; Tovar, EduardoImproving urban dwellers quality of life requires mitigating traffic congestion, minimizing waiting delays, and reducing fuel wastage and associated toxic air pollutants. Battery-electric vehicles (BEVs) are envisioned as the best option, thanks to zero exhaust emissions and regenerative braking. BEVs can be human-driven or autonomous and will co-exist with internal combustion engine vehicles (ICEVs) for years. BEVs can help at complex intersections where traffic is saturated. However, their benefits can be reduced by poor intersection management (IM) strategies that coordinate mixed traffic configurations inefficiently. This paper studies energy savings and emissions reduction using BEVs mixed with human-driven ICEVs under eight relevant IM approaches. It shows that adding BEVs has impacts on throughput, energy consumption, waiting delays, and tail-pipe emissions that depend on the specific IM approach used. Thus, this study provides the information needed to support an optimal choice of IM approaches considering the emerging trend towards electrical mobility.
- Synchronous Framework Extended for Complex IntersectionsPublication . Reddy, Radha; Almeida, Luís; Gutiérrez Gaitán, Miguel; Santos, Pedro Miguel; Tovar, EduardoIntelligent intersection management systems are an integral part of Smart Cities and have a profound impact in urban traffic management. I n a previous work, the authors proposed a specific Intelligent Intersection Management Architecture (IIMA) with the associated Synchronous Intersection Management Protocol (SIMP) for simple single-lane isolated intersections that outperformed other competing protocols in throughput, time loss and polluting emissions. IIMA/SIMP supports both autonomous and human-driven vehicles. This paper extends such work to more complex multi-lane intersections, comparing against traditional and intelligent intersection management approaches. Simulation results achieved with SUMO confirm the advantages of IIMA/SIMP even in complex intersections, improving throughput, average speed, waiting time, trip time loss, and associated fuel consumption.obs: Extended Abstract has been accepted and invited for full-paper submission.
- Synchronous Intersection Management to reduce Time LossPublication . Reddy, Radha; Almeida, Luis; Santos, Pedro M.; Bouzefrane, Samia; Tovar, EduardoConventional intersection management that allows multiple vehicles from one road at a time, e.g., Round-Robin (RR), may constitute bottlenecks in urban traffic management. Consequently, new intelligent intersection management (IIM) approaches were proposed to reduce time loss, fuel wastage, and ecological damage. IIM is also suited to take advantage of the new communication capabilities of autonomous vehicles that are gaining relevance, though still co-existing with human-driven vehicles. This paper extends the analysis of a recently proposed synchronous IIM system, the Synchronous Intersection Management Protocol (SIMP), that is compared with the RR scheme in a four-way single-lane intersection as those found in urban residential areas, under maximum vehicle speeds of 30Km/h and 50Km/h and various traffic arrival rates. We characterize performance by measuring time loss, i.e., the additional trip delay due to forced slowdown, and fuel consumption using a model for standard vehicles with internal combustion engines. The experimental results obtained with the SUMO simulation framework indicate an advantage for SIMP in both metrics, approximately halving the values achieved with the best RR approaches and with high traffic rates.
- Synchronous Management of Mixed Traffic at Signalized Intersections towards Sustainable Road TransportationPublication . Reddy, Radha; Almeida, Luis; Gutiérrez Gaitán, Miguel; M. Santos, Pedro; Tovar, EduardoIn urban road transportation, intersections are traffic bottlenecks with increased waiting delays and associated adverse effects. A recently proposed intelligent intersection management (IIM) approach, the Synchronous Intersection Management Protocol (SIMP), synchronizes the vehicles access to simple single-lane isolated intersections, outperforming competing approaches in various performance metrics. In this paper, we apply SIMP to multi-lane intersections, increasing significantly the applicability of the protocol while dealing with the additional complexity emerging from the multiple crossing conflicts. Using the SUMO simulator, we compare the performance of SIMP with two conventional (Round-Robin - RR and Trivial Traffic Light Control - TTLC) and two IIM approaches (Intelligent Traffic Light Control - ITLC and Q-learning based Traffic Light Control - QTLC) under continuous and interrupted upstream traffic flows scenarios in urban settings. The results using a maximum speed of 30km/h confirm the superiority of SIMP, improving traffic throughput (~14.4%) and reducing travel delays (~64.4%) and associated fuel consumption (~25.5%) when compared to the best of the other approaches.
- Waiting Time Analysis for a Network of Signalized IntersectionsPublication . Reddy, Radha; Almeida, Luis; Santos, Pedro M.; Tovar, EduardoVehicle waiting time or stopped delay is one of the major disadvantages of employing signalized intersections (SIs) in road networks. The waiting time delays occur when vehicles stop in the queue, waiting to access the SI, and vary from road lane to road lane with the intersection management (IM) protocol used. In this research line, we propose an analytical expression for estimating the waiting time delays and studying the performance of different IM approaches in a grid network of independent intersections. We consider complex intersections with four legs and two lanes with two left-lane configurations, as well as five state-of-the-art IM approaches: two conventional -- Round-Robin (RR) and Trivial Traffic Light Control (TTLC); two adaptive -- Max-pressure Control Algorithm (MCA) and Websters Traffic Light Control (WTLC); and one reactive -- Synchronous Intersection Management Protocol (SIMP). The waiting time performance of these five IM approaches is compared using two simulation scenarios in the SUMO simulation framework. The simulation results validate the analytical study and show the advantages of employing SIMP, being the IM approach with the lowest waiting time delays.
- Work-in-Progress: Exploring the Composition of Synchronous Intelligent IntersectionsPublication . Reddy, Radha; Almeida, Luís; Santos, Pedro Miguel; Tovar, EduardoPrivate vehicles are expected to continue representing a large share of the urban traffic requiring intelligent management to provide safe and efficient urban mobility. In this context, it is imperative to mitigate traffic congestion and associated travel delays to improve the quality of life of urban dwellers. This paper explores the global performance of grid networks of independent intersections using different intersection management protocols. We particularly aim to compare the performance achieved when using the intelligent intersection management architecture (IIMA) that relies on the synchronous intersection management protocol (SIMP), against two conventional (Round-robin - RR and trivial traffic light control - TTLC) and two adaptive (Max-pressure control algorithm - MCA and Websters traffic light control - WTLC) intersection management approaches. We consider four-way two-lane intersections with two crossing configurations, namely dedicated and shared left lane, on a 2×2 grid network of intersections. Simulation results with SUMO show that composing intersections with synchronous management considerably improves the network throughput and reduces travel delays.