Analysis of Flush Structural Supports and Design Equations for TxDOT Curb Inlets (Download PDF)
Frank E. Schalla, Graduate Research Assistant; Muhammad Ashref, Graduate Research Assistant
The new TxDOT standard pre-cast on-grade curb inlet uses 6-inch flush supports for the top slab of a curb inlet. HEC-22, the state of the art design method used by TxDOT, states flush supports can reduce an inlet’s interception capacity by as much as 50% yet do not provide any guidance on quantifying the effects of flush slab supports. Full-scale physical modeling was performed to investigate the effects of flush supports on interception capacity and to compare curb inlet interception capacity with current TxDOT design methods. No measurable difference in interception capacity was found between curb inlets with flush supports or without. The 5-foot curb inlet model aligned well with TxDOT design equations while the 15-foot curb inlet model intercepted significantly less than TxDOT design equations predicted, which overestimated intercepted flow by an average of 80%. This implies that 15-foot curb inlets significantly underperform compared to their design criteria. Research related to TxDOT Research Project 0-6842
Beam Design for Beam Switching Based Millimeter Wave Vehicle-to-Infrastructure Communications
Vutha Va (WNCG, UT); Takayuki Shimizu (Toyota InfoTechnology Center); Gaurav Bansal (Toyota InfoTechnology Center), Robert W. Heath Jr. (WNCG, UT)
Beam alignment is a source of overhead in mobile millimeter wave communication systems due to the need for frequent repointing. Beam switching architectures can reduce the amount of repointing required by leveraging position prediction. This paper presents an optimization of beam design in terms of rate. We consider a non-congested two-lane highway scenario where the road side units are installed on lighting poles. We formulate and solve numerically using a gradient descent method for an optimal beam design to maximize the data rate for non-overlap beams. The result shows very close performance to the equal coverage beam design. We then investigate the effect of the overlap on the average rate and outage and compare the equal coverage with the equal beam width design. This study provides insights into the design of Gbps data rate at mmWave bands. Such high data rate links will enable sensor data sharing between infrastructure and/or vehicles which will be an important component in automated driving. Research from the D-STOP Tier 1 University Transportation Center
Decision Support System for Selection of Project Delivery Method
Mayra S. Martinez; William J. O’Brien, Ph.D., P.E. (Professor); James T. O’Connor, Ph.D., P.E. (Professor); Nabeel Khwaja, P.E. (Research Engineer)
Alternative Project Delivery methods (PDMs) have been adopted by several public and private agencies since the past few decades. Availability of multiple options for PDMs necessitates development of formal decision support systems to determine the appropriate choice. This study developed a transparent and flexible decision support system for TxDOT to analyze the suitability of Design-Bid-Build (D-B-B) vs. Design-Build (D-B). Research supported through the TxDOT Dallas District IAC.
Dynamic Network Loading Model of Autonomous Vehicle Behavior (Download PDF)
Rahul Patel, Research Assistant; Michael W. Levin, Doctoral Candidate, Stephen D. Boyles, Assistant Professor
Autonomous vehicles (AVs) offer new traffic behaviors that could revolutionize transportation, such as the reservation-based intersection control and reduced reaction times that result in greater road capacity. Recent developments in reservation models and multiclass cell transmission models for AVs in dynamic traffic assignment have allowed studies of larger networks. This paper presents analyses of several highly congested arterial and freeway networks to quantify how reservations and reduced reaction times affect travel times and congestion. Reservations were observed to improve over signals in most situations. However, signals outperformed reservations in a congested network with several close local road-arterial intersections. On the other hand, the increased capacity due to reduced following headways resulted in significant improvements for both freeway and arterial networks. Finally, we studied a downtown network, including freeway, arterial, and local roads, and found that the combination of reservations and reduced following headways resulted in a 78% reduction in travel time. Research related to TxDOT Research Project 0-6847
Forward Collision Vehicular RADAR with IEEE 802.11: Feasibility Demonstration through Measurements
Enoch Yeh, Graduate Student
Recent mandates for automation in vehicular transportation safety have increased demand for radar applications such as forward collision detection and avoidance. The majority of current implementations of vehicular radar are mmWave radars, which are expensive and exhibit multiple security vulnerabilities, such as radar spoofing. We have demonstrated the feasibility of implementing dedicated short-range communications (DSRC) technology with radar capabilities by designing a secure and cost-efficient Wi-Fi based (IEEE 802.11) radar system. Current measurements demonstrate that our solution delivers meter-level accuracy for single-target detection with just 20 MHz of bandwidth, which supports significant potential cost reduction of future releases of vehicular radar. Research related to TxDOT Research Project 0-6877 (CAR-STOP)
IEEE 802.11ad V2X-Radar: A Joint Millimeter-Wave Vehicular Communication and Radar System
Preeti Kumari, Graduate Research Assistant; Nuria G. Prelcic, Professor at Universidade de Vigo, Spain; Junil Choi, Post Doctorate; Robert Heath, Professor at UT Austin
Proprietary millimeter wave (mmWave) radar technologies are widely used in luxury cars to discover information about the surrounding environment and enable intelligent transportation systems (ITS) such as cruise control and collision avoidance. Radar sensing, when supplemented by mmWave vehicle-to-vehicle (V2V) communication technologies, would enable an ultra-low latency and standards-based transfer of crucial information essential for ITS. MmWave V2V communication technology, however, is not yet adopted in the automotive industry. In this poster, an IEEE 802.11ad V2V-radar system is proposed that enables both radar and communication mmWave technologies to exploit the same spectrum and to leverage shared hardware based on the mmWave consumer wireless local area network (WLAN) standard. Shared resources allow IEEE 802.11ad V2V-radar to simultaneously reap the benefits of high resolution sensing (via radar) and ultra-low latency cooperative information exchanging, such as raw sensor data and entertainment content, among vehicles (via V2V communication) at lower cost. Research related to TxDOT Research Project 0-6877 (CAR-STOP)
Implications of Traffic Signal Security on Potential Deliberate Traffic Disruptions (Download PDF)
Kenneth A. Perrine; Michael W. Levin; Melissa Duell, PhD; Stephen D. Boyles, PhD
Traffic control systems all have the capacity to be vulnerable to malicious attacks. Although several studies on outages and attacks have been conducted in the literature, effects of attacks on signals have not been specifically studied. There is a need for risk assessments to be conducted within traffic operations agencies. A key factor is to gain an idea of the hypothetical impact of an outage. In this study, a dynamic traffic assignment network is used to model a central business district, where traffic signal-controlled intersections are selectively disabled. In one scenario, total delay is multiplied fivefold when a quarter of signals are randomly disabled. If the attacker prioritizes the selection of signals according to intersection traffic volume, significantly fewer signals are needed to exert the same impact. To complement work conducted by agencies in drafting cybersecurity policies, recommendations are made for a suite of practical analysis tools that traffic operations and computer networking engineers can use to quickly check for the worst vulnerabilities.
Improving Flood Preparedness in South-Central Infrastructure (Download PDF)
Cassandra Fagan, Graduate Research Assistant
Recent flood events in South-Central Texas devastated communities and highlighted the need for increased flood preparedness. Wimberley, Texas was arguably the most affected by the 2015 Memorial Day flood; flooding on the Blanco River resulted in several flood-related fatalities and extensive property damage. The transportation network is particularly vulnerable during these events, with many flood fatalities occurring on roadways. Thus, in order to prevent future tragedies, improvements in flood preparedness and forecasting at the local level must be a priority. This study investigates improving emergency response at the local level by 1) down-scaling an ensemble forecasting system to extend forecast lead times, and 2) creating a planning tool for emergency responders to use before and during emergencies on high priority reaches in Travis & Williamson County. These efforts will increase the time available to emergency responders to barricade roads, and evacuate communities that are at risk of being flooded.
On the Security of Millimeter Wave Vehicular Communication Systems using Random Antenna Subsets (Download PDF)
Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and / safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy rate when compared to conventional array transmission techniques. Research from the D-STOP Tier 1 University Transportation Center
A Spatial Allocation Approach for Post-Earthquake Urban Roadway Network (Download PDF)
Zhe Han, Ph.D. Candidate, Graduate Research Assistant; Zhanmin Zhang, Clyde E. Lee Endowed Professor
Violent earthquakes have occurred in the past decade. The restoration of post-earthquake roadway networks has attracted the attention of engineers and researchers. The primary challenge for solving this problem is to determine how the resources should be allocated in terms of the relative importance of each roadway section in the network. This research proposes an edge betweenness centrality based approach to incorporate relative importance of roadway sections into the prioritization of post-earthquake urban roadway networks for restoration. To implement the proposed methodology, an assessment system for post-earthquake urban roadway network restoration was developed using a geographical information system. The roadway network in the city of Shijiazhuang was employed to validate the proposed methodology. The results show that the proposed methodology can be used to not only obtain the weight of each roadway section in a large-scale roadway network, but also help conduct resource allocations for restoring post-earthquake urban roadway networks.
Using Parcel Data to Inform Centroid Connector Placement
Rachel James, Graduate Research Assistant at The University of Texas at Austin; Mason Gemar, PhD, Research Associate at The Center for Transportation Research
Simulation-based dynamic traffic assignment (DTA) models are particularly sensitive to the topological detail of the traffic network, including the location of centroid connectors. Traditional centroid connector placement strategies may lead to excessive congestion and unrealistic traffic patterns, while manual network refinement is prohibitive in large regional models. This research effort utilizes parcel-level data to inform an automated centroid connector placement methodology with the goal of producing more realistic network loading patterns. Parcel-level data is used to allocate travel demand between two sub-regions in each considered traffic analysis zone, and to select appropriate nodes for the centroid connector placement. Numerical experiments, conducted on a medium-size network in the Austin, TX region, suggest that the proposed approach better approximates both corridor travel times and traffic counts throughout the network, with improvements of more than 40 percent in travel time estimation accuracy, and 12 percent in traffic count estimation. Research from the D-STOP Tier 1 University Transportation Center
Visualization for the North Tarrant Express 35W Project
Cameron Schmeits, Research Associate; Nabeel Khwaja, P.E., Research Engineer, Assistant Director
This poster shows how 3D and 4D modeling has assisted TxDOT in a variety of ways during construction of the $1.4 billion North Tarrant Express 35W project. Research supported through the TxDOT Dallas District IAC.