Stephen P. Mattingly

Reaction to the Managed Lane Concept by Various Groups of Travelers

Increased traffic combined with a lack of financial resources to reduce the resulting congestion is pushing many state departments of transportation to examine alternative financing and congestion mitigation techniques. The use of managed lanes (MLs) is one measure that addresses both issues at the same time. MLs are defined in this context as priced lanes on a freeway that also has toll-free lanes. MLs may have a considerable advantage over traditional toll roads in that in many cases it is politically impossible to institute tolls on an existing toll-free highway. Understanding the publics reaction to MLs is critical for their successful implementation. This paper reports the results of a survey of more than 4,600 travelers regarding their feelings toward, and the potential use of, MLs. This research reveals strong interest in the ML concept among residents of metropolitan regions in Texas. The potential ML users indicated that travel time savings and increased travel time reliability were the strongest contributors to their opinions. Current carpoolers identified the ability to drive alone as being more important than the ability to carpool. This indicated that additional incentives may need to be provided to carpoolers to prevent some from converting to single-occupant vehicles or that current carpoolers appreciated the flexibility to gain the same advantages in terms of lane use on those days that they have to drive alone. Respondents who currently pay tolls were more likely to express interest in using MLs. This coincides with tolls being named as the least desirable aspect of MLs among those individuals who were not interested in using them.

Comparison of quality of service in two central business districts two-fluid model approach in Texas

In 2003-2004, the City of Fort Worth, Texas, undertook an exercise to retime traffic signals, to convert several one-way streets to two-way streets, and to make significant changes to the land use in the downtown area. Those changes were expected to have a significant impact on the quality of service of the downtown street network. After an urban street network undergoes modifications of its control system or geometric configuration as in Fort Worth, there is a need to have quantifiable tools to perform before-and-after studies on network quality of service. The purpose of this study was to use the two-fluid model to compare network performance over time and after a recent major modification. In 1983 and 1994, the two-fluid model was calibrated for the Dallas and Arlington, Texas, networks. The model was then recalibrated for the two networks with data collected in 2003; this allowed comparisons of the quality of traffic service in these networks over a long time. To assess the changes in Fort Worth, a new model was calibrated with data collected in 2004 and was then compared with the previous model calibrated in 1999. This comparison helped determine the success of signal retiming strategies as well as modifications in street geometry and land use. As expected, changes occurred in the system over time, but those changes, both positive and negative, differed, depending on the city.

Field Operational Test of Integrated Freeway Ramp Metering/Arterial Adaptive Signal Control: Lessons Learned in Irvine, California

A systematic evaluation of the performance and effectiveness of a field operational test (FOT) of an integrated corridor-level adaptive control system was attempted from fall 1994 through spring 1999 in Irvine, California. The FOT was conducted by a consortium consisting of the California Department of Transportation (Caltrans), the city of Irvine, and two private-sector consultants—National Engineering Technologies Corporation and Farradyne Systems, Inc., a division of Parsons Brinckerhoff—with the city of Irvine as the lead agency. The FOT was a cost-share funded by FHWA as part of the Intelligent Vehicle Highway System Field Operational Test Program. The FOT involves an integrated advanced transportation management system, which extends the capabilities of existing traffic management systems in the city of Irvine and in Caltrans District 12. The evaluation originally entailed both a technical performance assessment and a comprehensive institutional analysis. This report of the Irvine FOT does not constitute a technical evaluation because of the failure of any of the planned technologies to be successfully implemented in the field. Because of the extended time frame associated with the project and the significant range of technical and institutional issues associated with the development and eventual failure of the FOT, a summary of project development, institutional barriers, and lessons learned is provided.

Anaheim Advanced Traffic Control System Field Operations Test: A Technical Evaluation of SCOOT

Abstract This article provides a technical evaluation of the traffic control element of the Anaheim Advanced Traffic Control System Field Operations Test (FOT), sponsored by the US Department of Transportation. The primary objective for this test was the evaluation of adaptive traffic signal control technologies, including the Split Cycle and Offset Optimization Technique (SCOOT) for intersection signal control. The SCOOT evaluation was defined relative to existing, first generation Urban Traffic Control System (UTCS)-based control using standard US field detectorization. This US geometry is not the detector configuration normally used with SCOOT. SCOOT was implemented with some degree of success, though technical problems limited its performance. Anaheims existing communication and controller systems contributed major deployment limitations since they were less adequate than anticipated. SCOOT remains in use in selected areas, with plans for system expansion.

Decision-Making Procedure for Assessing Performance Measures of Freeway Operations

Performance measurement is a method to quantify project success based on project and policy outputs and outcomes assessment. In the United States, transportation-related performance measures have become popular since authorization of the Intermodal Surface Transportation Efficiency Act in 1991. Performance measures have been applied in many areas, including freeway operations. This paper improves on earlier techniques and presents an innovative approach for using a multicriteria decision framework to select freeway operational performance measures. The proposed selection performance measure methodology includes establishing a statement of purpose, identifying alternatives, establishing criteria, and using a screening approach to eliminate unsatisfactory performance measures by means of qualitative and quantitative criteria. Once the screening approach is used to reduce the set of candidate alternatives to a set of feasible alternatives, the methodology uses a multicriteria decision model, such as simple additive weighting and ELECTRE III, to combine the commensurate criteria and generate a rank order of the acceptable alternatives for final decision making. A sample application of the proposed methodology is presented.

Traffic Flow of Connected and Automated Vehicles: Challenges and Opportunities

Significant progress has been observed in recent years in the development of connected and automated vehicles (CAVs). Such progress has been publicized through the latest products/applications being released or announced by the industry. However, there is a limited knowledge on the impact of CAV technologies on surface transportation network performance. In particular, the technological specifications associated with CAVs and the response of drivers to such technologies are not well integrated into traffic flow models. These models are needed to assess and evaluate the safety and mobility impact on our roadway conditions. Accordingly, a more elaborate discussion is needed between three entities: (1) the industry partners leading the efforts in developing CAVs; (2) the academic traffic flow modeling community researching the impact of CAVs on traffic flow performance; and (3) the public/government agencies devising the standards and the rules to regulate the deployment of CAVs on our roadway network. This chapter summarizes the presentations of speakers from these three entities during the Automated Vehicles Symposium 2016 (AVS16) held in San Francisco, California on July 19–21, 2016. These speakers participated in the break-out session titled “Traffic Flow of Connected and Automated Vehicles”. The corresponding discussion and recommendation are presented in terms of the lessons learned and the future research direction to be adopted. This session was organized by the AHB45(3) Subcommittee on Traffic Flow Modeling for Connected and Automated Vehicles.

Unmanned aerial vehicle routing in the presence of threats

Abstract We study the routing of Unmanned Aerial Vehicles (UAVs) in the presence of the risk of enemy threats. The main goal is to find optimal routes that consider targets visited, threat exposure, and travel time. We formulate a mixed integer linear program that maximizes the total number of visited targets for multiple UAVs, while limiting both the route travel time for each UAV and the total threat exposure level for all UAVs to predetermined constant parameters. The formulation considers a set covering vehicle routing problem where the risk of threat exposure and the travel time are modeled for each edge in a vehicle routing network. To reduce threat exposure, waypoints are generated within the network so routes can avoid high-risk edges. We propose several waypoint generation methods. Using the candidate waypoints, the UAV routes are optimized with branch-and-cut-and-price (BCP) methodology. Minimum dependent set constraints and a simple path heuristic are used to improve the computational efficiency of the BCP algorithm. Computational results are presented, which show that the BCP algorithm performs best when the number of waypoints generated a priori is about half the number of targets.

Determination of Safe Roadway Buffer Width to Protect Human Healthfrom NO2 Exposure: A Case Study for Grand Prairie, TX

According to the U.S. Environmental Protection Agency (EPA), in 2010 mobile sources in the U.S. contributed 58% of carbon monoxide (CO), 56% of nitrogen oxide (NOx), and 33% of Volatile Organic Compounds (VOCs). Onroad sources also emit a variety of air toxics, including benzene, toluene, and xylenes. The case study presented here determines a safe roadway buffer width to protect human health from nitrogen dioxide (NO2) exposure along an arterial in Grand Prairie, Texas. NO2 health effects include eye, nose, throat, and lung irritation; cough; shortness of breath; tiredness and nausea. In the Dallas Fort Worth region, where Grand Prairie is located, on-road vehicles contribute about half of NOx emissions. Vehicle NOx emission rates along Great Southwest Parkway were measured using a Horiba 1300 OBS onboard emission measurement system, to determine a maximum g/mile emission factor for the corridor. Hourly DFW meteorological data for a 5-year period was processed using CAL3QHCR to determine the 10 worst-case hourly meteorological combinations. The maximum emission factor and worst-case meteorological conditions were input into the line source dispersion model CALRoads View to determine worst-case NO2 concentrations at 5- m intervals away from the roadway. CALRoads View output was post-processed in Arc View GIS to plot concentrations at receptor locations. Worst-case concentrations were compared to the 1-hour NO2 National Ambient Air Quality Standard (100 ppb). For the current Great Southwest traffic volume, it was found that the standard would not be exceeded. Additional CALRoads View runs were conducted to determine how much the traffic volume could increase, and still avoid exceedances outside a 20-foot buffer width, which is a common setback distance in residential areas. It was determined that the traffic volume could increase by a factor of 10 and still protect human health from NO2 impacts, using a 20-foot buffer.

Development of Managed-Lane Access Guidelines Based on Gap Acceptance Theory

One strategy for improving freeway performance is implementation of managed lanes (MLs). Vehicles access an ML located in the freeway median by weaving across the general purpose lanes (GPLs) and entering the ML from the leftmost lane of the GPLs. Such intense lane-changing maneuvers cause traffic turbulence, which induces special operational problems with capacity, level of service, and safety. The principal objective of this research is to develop design guidelines for the ML access (or exit) spacing between the entrance (or exit) ramp and the ML access opening and for the ML access opening length. This research develops analytical weaving models based on gap acceptance theory; the models estimate the probability of successful weaves in these weaving distances. The research also develops design guidelines for these distances on the basis of the analytical weaving models.

Travel Behavior of Largest Minority Cohorts in Texas

Texas is changing dramatically; minority cohorts are expected to grow and become more than 65% of the Texas population before 2035. When considering issues of environmental justice, transportation professionals in Texas must seek to identify how these demographic changes will affect the transportation system. Gaining an understanding of this problem requires that the prevalent travel behavior and attitudes of minority populations be considered. The research presented in this paper investigates the prevailing travel behavior of the three largest minority cohorts in Texas: U.S.-born Hispanics, Hispanic immigrants, and African Americans. Considering environmental justice, this paper focuses on a study performed to identify the travel behaviors of the minority cohorts of Texas. The researchers used the National Household Travel Survey Add-On for Texas, because it allowed them to examine respondents by race–ethnicity and immigrant status. On the basis of the studys results, it was found that U.S.-born Hispanics emulate Caucasian travel behavior most closely; however, U.S.-born Hispanics have higher nonwork-trip generation rates. Moreover, multivariate analysis indicated that Hispanic immigrants drive less than U.S.-born Hispanics, even after accounting for sociodemographics. The study also revealed that African Americans, Hispanic immigrants, and single adults with children produce most transit trips in urban Texas. This study further indicated that Hispanic immigrants–-given their high household sizes, low income, and low vehicle availability–-may be incurring mobility problems. The findings in this study indicate that Texas may be facing a transportation–cultural change because of the different travel characteristics of rapidly growing minority cohorts.