Addressing Concerns of the LBJ Express Depressed Managed Lanes: Signage and Sunlight Analysis (Download PDF)
Nabeel Khwaja, P.E.; Cameron Schmeits
The LBJ Express project has several miles of managed toll lanes that are depressed and partially covered by the free highway lanes above. The amount the managed lanes are covered varies along the length of the project depending on how much right of way was available. Also, to support the highway lanes above where they overlap the managed lanes requires them to be partially on bridge. This means there is a bent cap that crosses over the managed lanes every 100 ft to support the beams. These conditions present shadow patterns and amounts of sunlight that change throughout the day and the year. The 3D model and visualization software that mimics accurate sunlight were used to create several videos from the driver’s perspective to show approximately how much sunlight is reaching the depressed managed lanes and what the shadows look like.
Bid Price Analysis (Download PDF)
Amit Kumar Singh, Dr. Khali Persad
Before letting any project, engineers at Texas Department of Transportation have to estimate unit bid prices for winning bidder. Our team at the Center for Transportation Research, UT Austin has created a tool which can be used for plan estimate development to achieve plan estimate within 5% of contractor’s bid for each plan set. This tool automatically consolidates and analyzes previous bid tabs to estimate the best bid items prices. A separate version of this tool has been developed to detect the unusual projects where engineer’s estimate of total project cost and winning bidder bid for total project cost deviates more than a given threshold. Additionally, this tool identifies crucial items within a project that are responsible for deviation in Engineer’s estimate and winners bid. This tool has been built entirely using excel VBA and does not require any sophisticated programming packages or solver. This tool has been found to provide better and reliable price estimates on previous projects.
Combining MmWave Automotive Radar and Communication
Millimeter wave (mmWave) technology is widely used for automotive radar applications, like adaptive cruise control and obstacle detection. Unlike conventional radar waveforms which are usually propriety, this poster will explore the use of a consumer wireless local area network (WLAN) waveform for automotive radar application. In particular, this poster develops a joint framework of long range automotive radar (LRR) and vehicle-to-vehicle communication (V2V) at 60 GHz by exploiting the special data-aided structure (repeated Golay complementary sequences) of a IEEE 802.11ad single carrier physical layer (SCPHY) frame. This framework leverages the signal processing algorithms used in the typical WLAN receiver for time and frequency synchronization to perform radar parameter estimation. The initial simulation results show that it is possible to achieve the desired range accuracy of 0.1 m with a very high probability of detection (above 99%) using the preamble of a SCPHY frame. Furthermore, the velocity estimation algorithm achieves the desired accuracy of 0.1 m/s at high SNR using the preamble and pilot words of only a single frame.
Communicating Complex Construction and Traffic Control to the Public (Download PDF)
Nabeel Khwaja, P.E.; Cameron Schmeits
The FM 407 cross street along IH-35E was planned to be reconstructed approximately 10 years ago. Due to funding issues and other circumstances, construction of this small portion of the IH-35E highway was delayed and eventually combined with the 35 Express Project. FM 407 is being changed from an under pass to an overpass as well as a partial cloverleaf to a diamond intersection. Completing that transformation is complex and requires complex traffic control. Those issues, combined with the significant delay have local residents and city officials very interested in the progress of this project. 3D Construction animations showed the demolition and reconstruction of FM407 and IH-35E as well as the flow of traffic during each phase. The integration of the 3D models and construction schedule with the traffic into one video was very helpful explaining the project to city official and the public in a complete and concise visual platform.
Consumer Preferences and Willingness to Pay for Advanced Vehicle Technology Options and Fuel Types
The automotive industry is witnessing a revolution with the advent of advanced vehicular technologies, smart vehicle options, and fuel alternatives. However, there is very limited research on consumer preferences for these types of vehicles. But the deployment and penetration of advanced vehicular technologies in the marketplace, and planning for possible market adoption scenarios, calls for collection and analysis of consumer preference data related to these emerging technologies. This study aims to address this gap, offering a detailed analysis of consumer preference for alternative fuel types and technology options using data collected in choice experiments conducted on a sample of consumers in South Korea. The results indicate that there is considerable heterogeneity in consumer preferences for various smart technology options such as wireless internet, vehicle connectivity, and voice command features, but relatively little heterogeneity in the preference for smart vehicle applications such as real-time traveler information on parking and traffic conditions.
Development of Detailed Plan Review Management Tool (Download PDF)
The District Design Office reviews plans from various District offices at 30, 60, 90% completion and before letting. Comments on each plan sheet are tracked manually. UT-CTR is developing a Plan Comments Management Tool to ensure comments are properly tracked and addressed. The tool provides a user-friendly interface and features such as sorting, filtering and reporting.
Early Warning System to Detect Land Use Changes (Download PDF)
Jake Gutekunst, Matt Reiter, Ahmad Alrashidan, Randy Machemehl
Empirical Bayes Before-After Study on Safety Effect of Narrow Pavement Widening Projects in Texas (Download PDF)
Hui Wu, Zhe Han, et al.
Texas has approximately 40,000 lane miles of two-lane farm-to-market (FM) and ranch-to-market (RM) roads with total paved widths of 18 to 22 ft, most of which are in rural areas. The main reasons for roadway widening are usually to improve safety, increase structural capacity, and/or enhance pavement performance. The goal of this study is to investigate the safety effects of narrow pavement widening projects for rural two-lane FM/RM roads in Texas. A before-after comparison study was conducted based on 22 projects using the empirical Bayes method to evaluate how wider lanes/shoulders impact crash occurrence by type and severity. The results showed that there was a significant reduction of total crashes as with other types of crashes, such as run-off-the-road and head-on crashes. These findings suggest that narrow pavement widening is an effective safety countermeasure on narrow two-lane FM/RM roads in rural areas.
Enabling Millimeter Wave Multi-Gbps Wireless Broadband for High Speed Trains (Download PDF)
Vutha Va, XinchenZhang, and Robert W. Heath Jr.
This paper considers a millimeter wave (mmWave) system that enables multi-Gbps wireless service for high speed trains. MmWave systems require proper beam alignment to achieve good performance making it difficult to apply to high speed trains due to the need for frequent realignment. In this paper, using the IEEE 802.11ad system parameters, we first show that the channel coherence time will not be enough for communication with wide beams, and thus conventional approaches based on beam sweeping become inefficient if not impossible. Then we consider a beam switching approach that leverages the position information from the train control system for efficient beam alignment. Using this network architecture, we investigate the optimal choice of beamwidth and show that a properly optimized system can achieve multi-Gbps throughput.
GIS Tools for Displaying 4-year Plan Projects (Download PDF)
Zhe Han, et al.
TxDOT District Pavement Engineer develops a 4-year plan for their District each year based on PMIS data and other criteria, and usually meets with the Area Engineers to finalize the 4-year plans. The mapping tool visualizes PMIS database and shows planned project locations, treatment types and treatment timing to District Administration for further consideration. It also assists TxDOT District Pavement Engineer during meetings with the Area Engineers in terms of more effective communication. The tool is implemented in both desktop version and online version using ArcGIS.
Impact of Network Accessibility on Schedule-based Transit Assignment (Download PDF)
Alireza Khani, Ehsan Jafari, Jackson Archer, Tyler Beduhn
Accessibility models have been studied in the literature for planning purposes for a long time. However, as transportation models are being improved in spatial and temporal resolution, the effect of accessibility on transit assignment needs to be thoroughly examined. We investigated improvements for modeling transit access in an assignment model. Two models are used to determine the transit accessible area in each traffic zone and to estimate the equivalent walking distance from each zone to each transit stop. The models, taking advantage of the network distance and distance decay factor, are alternatives to replace the buffer methods in assignment models. The accessibility models are then integrated with a schedule-based transit assignment model to determine the impact on route- and network-level transit usage. The integrated model is compared with the existing model, and results are evaluated by comparing with observed data from a transit on-board survey. The evaluation shows significant improvement in the effectiveness of the assignment model in estimating route ridership.
Intersection auctions and reservation-based control in dynamic traffic assignment (Download PDF)
Michael W. Levin, Stephen D. Boyles
Autonomous vehicle (AV) technology is maturing, with AVs test-driving on public roads. A promising intersection control policy (TBR) proposed by Dresner and Stone (1) offers the potential to improve intersection capacity beyond the capabilities of optimized traffic signals. Although TBR has been studied in several micro-simulation models, it has yet to be analyzed under user equilibrium behavior. Towards this goal, we model TBR in dynamic traffic assignment to draw on its extensive literature on vehicle routing behaviors. The proposed model makes TBR computationally feasible to be simulated on large city networks with the goal of solving traffic assignment. TBR also offers benefits through arbitrarily prioritizing vehicle movement. We perform an in-depth study of simple intersection auctions and find that much of its benefits over first-come-first-serve prioritization result from the randomizing effect of auctions giving larger queues of vehicles greater shares of the intersection capacity.
Introducing Non-Normality of Latent Psychological Constructs in Choice Modeling with an Application to Bicyclist Route Choice
Subodh K. Dubey
The use of latent psychological constructs (such as attitudes, perception, values and beliefs) in random utility model (Integrated Choice and Latent Variable (ICLV)) provides the necessary nexus between predictive and behavioral choice analysis approaches. The popularity of ICLV model has grown considerably in last decade, thanks to availability of high-dimensional survey data. However, the use of such data may violate the assumption of normality due to non-normal features (exhibited by data) such as asymmetry, heavy tails, and even multimodality. Thus to tackle this issue, we propose the use of a multivariate skew-normal (MSN) distribution function for the latent psychological constructs in the ICLV model system (SN-ICLV). The proposed SN-ICLV model is applied to model bicyclists’ route choice behavior using a web-based survey of Texas bicyclists. The results reveal evidence for non-normality in the latent constructs.
Investigation Of Centroid Connector Placement For Advanced Traffic Assignment Models With Added Network Detail (Download PDF)
Ehsan Jafari, Mason Gemar, Natalia Ruiz-Juri
Added Network Detail Advanced traffic assignment models typically incorporate more detailed network representations than traditional planning models. In this context, the placement of centroid connectors may have a significant impact on model performance and results. Centroid connectors are used to model the loading of vehicles into the network, and attention must be paid to their number and location in order to avoid unrealistic congestion or low utilization of minor roadways by local traffic. Given that the manual inspection of centroid connector placement may be too time consuming in large regional networks, two simple automatic centroid connector placement strategies are presented here, along with their impact on the resulting traffic flow patterns on local streets. As part of the evaluation of the methods, a new metric has been introduced, the locality factor, to describe the use of minor streets by local traffic. Subsequent experiments, conducted on two real-world networks, exemplify the impacts of the incorporation of local streets and the placement of centroid connectors on model results.
Latent-Segmentation Based Approach to Investigating the Spatial Transferability of Activity-Travel Models
Presenter: Sebastian Astroza; Authors: Zeina Wafa, Chandra R. Bhat, Ram M. Pendyala, and Venu M. Garikapati
Spatial transferability of travel demand models has been an issue of considerable interest, particularly for small and medium sized planning areas that often do not have the resources and staff time to collect large scale travel survey data and estimate model components native to the region. Traditional approaches to identifying geographical contexts that may borrow and transfer models between one another involve the exogenous a priori identification of a set of variables or criteria that are used to characterize the similarity between geographic regions. However, this ad hoc procedure presents considerable challenges as it is difficult to identify the most appropriate criteria a priori. To address this issue, this paper proposes a latent segmentation approach whereby the most appropriate criteria for identifying areas with similar profiles are determined endogenously within the model estimation phase. The methodology is demonstrated and its efficacy established through a case study in this paper that utilizes the National Household Travel Survey (NHTS) data set.
Map-Matching Algorithm for Applications in Multimodal Transportation Network Modeling (Download PDF)
Kenneth A. Perrine, Alireza Khani, Natalia Ruiz-Juri
Generalized Transit Feed Specification (GTFS) files have gained wide acceptance among transit agencies, which now provide them for most metropolitan areas. GTFS datasets are extremely relevant for the development of multimodal planning models, but require GPS points to be mapped to an underlying roadway network model. We present an open-source algorithm for performing this non-trivial task that is relevant for planning and real time in-field applications. The methodology maintains a set of candidate paths connecting successive geographic points, and is demonstrated with a traditional planning network, as well as crowd-sourced OpenStreetMap data. Experimental results suggest that our approach is highly successful even when the underlying roadway network is not complete. The proposed methodology is a promising step toward using novel and inexpensive data sources to transform and facilitate the way that transportation models are built and validated.
Network Modeling Center: TxDOT Project Applications (Download PDF)
Mason Gemar, Jen Duthie, Natalia Ruiz-Juri, Jackson Archer, Nan Jiang
The Network Modeling Center used dynamic traffic assignment (DTA) to model nine alternate scenarios of the planned I-35 corridor improvements through central Austin. A version of each scenario modeled was developed to represent AM and PM peak period conditions for a build-out year of 2025. The analysis was designed to help address neighborhood concerns about the impacts of alternate ramp configurations through the deck section. Results were presented to neighborhood representatives at several stakeholder meetings. Researchers also developed models to investigate the impacts to traffic during and after construction of grade separated interchanges along SH 71 in the City of Bastrop. DTA and microsimulation models were created to evaluate changes to area travel patterns and provide detailed examination of the performance of the intersections for various configurations. The results and recommendations from the analysis were presented to TxDOT, city officials, and the public.
On the early jamiton detection with minimal communication overhead
Mohammed Eltayeb, Robert Heath
Phantom traffic jams (jamitons), which are traffic blockages that arise without any obstructions or bottlenecks on highways, have recently gained much attention by transportation engineers. The creation of jamitons are linked to irregular driving behaviors that cause a chain reaction to the drivers that follow. It has been reported that a jamiton can be modeled as a traveling shock wave that travels in the opposite direction of traffic. This wave can create additional shock waves that may result in additional traffic. By exploiting this wave like structure structure, we proposed a block compressed sensing based algorithm that estimates the location and density of the jamitons along a road with only limited communication overhead. The proposed algorithm is agnostic to packet collisions, and hence it can easily be incorporated in current vehicular communication systems. We anticipate that the proposed algorithm can aid in suppressing traffic flow instabilities, and as a result, aid in reducing collisions.
Optimizing Environmental Sensor Station (ESS) Location through Weather-Sensitive Hotspot Analysis (Download PDF)
Amit Kumar Singh, Jia Li
Optimizing environmental sensor station (ESS) location is a central task in roadside weather information system (RWIS) design and planning. In this paper, we propose a data-driven approach for optimizing region-wide ESS locations. The idea lies in identifying crash hotspots that are sensitive to weathers, and monitoring these hotspots more closely than other non-sensitive locations. To this end, we derive a distribution-free statistic that can faithfully capture the weather-sensitivity attribute, and formulate a nonlinear program to maximize the total utility of ESS based on diagnosis of weather-sensitive hotspots. The proposed approach is simple to implement, so it is especially suited for large-scale applications involving complex road networks or a large number of road segments. We demonstrate its application with data of Austin, Texas.
Tool for enhancing General Notes development process
Moo Yeon Kim
The purpose of the General Notes is to provide, in one section of the plans, the various supplemental data required by the specifications. Currently, the Austin district design section maintains a master document containing templates of General Notes for each item, and engineers should copy and edit parts associated with a project from the master document manually to develop General Notes. The objective of this task is to enhance General Notes selection and development process by developing an automated tool. The tool provides functions such as selecting items, selecting paragraphs, editing documents, comparing before and after documents, and generating documents for uploading to Micro Station. By implementing the tool, significant reductions of General Notes developing time, and mistakes are expected. In addition, by keeping track of changes in the master document, the tailored General Notes with respect to project types and funding categories can be provided in the future.
Traffic Operations Assistance for the Dallas Horseshoe Project (Download PDF)
Kristopher Pruner, Nabeel Khwaja
The $800 million Dallas Horseshoe Project consists of reconstructing portions of I-30 and I-35E across the Trinity River along with the interconnecting roadway sections and ramps. The existing infrastructure is outdated functionally and rapidly deteriorating structurally. Due to its proximity to the Central Business District of downtown Dallas and other major traffic generators, mobility through the area during construction is of vital importance. This project is being carried out by TxDOT through the design-build model and CTR is providing ongoing assistance to TxDOT in the area of traffic operations during construction. This poster highlights some of the efforts undertaken by CTR to assist TxDOT in maintaining mobility as construction progresses.
Truck Trip Generation Model for Williamson County, Texas: Survey Analysis (Download PDF)
Mubassira Khan, Dr. Randy Machemehl
This paper uses ordered-response model and linear regression model structures to evaluate the demographic and land-use factors that affect truck trip generation at a regional level. The data used for this paper were collected from the business establishments located in Williamson County, Texas through a mailout-mailback survey conducted in year 2014. The paper presents the empirical results and discusses the policy implications of these results for urban planning. Model results show that industry type, size and the location of business establishments affect their truck trip generation behavior. Business establishments with larger number of employees are more likely to attract more truck traffic, whereas, businesses owning their trucks are more likely to produce more truck traffic. Businesses located in areas with higher land-values tend to generate less truck traffic whereas businesses located in industrial land-use types are likely to generate more truck traffic.
Use of LiDAR to Identify Vulnerable Infrastructure (Download PDF)
The emergence of wide-scale LiDAR data are allowing for new studies to take place that were previously not feasible with 10 m or 30 m digital elevation models. LiDAR data for Travis and Williamson County obtained from the Capital Area Council of Governments (CAPCOG) is being used in this study to obtain roadway elevation information to study three low-water crossings on Bee Caves Road, Austin TX that are prone to flooding. This data in combination with surveyed culvert information will be used to determine the design storm for the low-water crossing. The purpose of this study is to translate flood forecasts into actionable information for emergency responders. The National Interoperability Experiment, NFIE, will produce flow forecasts at the low-water crossing locations 15 hours in advance, giving emergency responders more time to address road closings and other flood planning tasks.
Visualization of Demolition and Construction Sequencing: A case study of the Dallas Horseshoe project (Download PDF)
Dr. William J. O’Brien, Nabeel Khwaja, Bharathwaj Sankaran, Jojo France-Mensah
3D/4D CAD modeling presents new opportunities to achieve significant benefits in the areas of constructability reviews, work zone management, clash detection and public information for highway projects. Nonetheless, the application of this technology and its processes have still not picked up enough momentum to trigger widespread adoption in the highway construction industry. Since 2003, the Center for Transportation Research (CTR) has successfully implemented 3D/4D CAD modeling applications on numerous TxDOT projects. This presentation focuses on the specific applications of 3D/4D CAD modeling for the Dallas Horseshoe (DHS) project. The modeling applications for this project included visualization of demolition activities of the extant Trinity Bridge for the different phases and advanced rendering and visualization of lane markings of the proposed IH30 bridges for enhanced communication to the public. Furthermore, a complete 4D simulation of the IH30 bridges are presented alongside the visualization of the proposed signature MMD bridges on this project for construction sequencing analysis.