Lane Line Markings in Advance of Lane-Reduction Transitions

DTFH61-13-D-00024Roadway lane-reduction transitions have long been reported to be problematic to drivers. Whether this problem is the result of a lack of understanding of lane-reduction signing or lane markings, a simple failure to comply with such markings, or other unidentified factors is unknown. This study, completed in 2016, explored driver comprehension of six different lane-reduction markings. The markings varied in terms of the incorporation and length of dotted and broken lines. In addition, half of the markings included a solid white line adjacent to the dotted/broken line. The supplemental solid white line resulted in improved understanding that the rightmost lane would end, earlier reported lane changes, and the highest preference ratings. Dotted lines also resulted in better understanding of an upcoming necessary lane change than did the longer, more traditional broken lane lines. This study contains recommendations and suggestions for lane-reduction marking changes to the Manual on Uniform Traffic Control Devices

Signing, in Combination with Lane Markings, in Advance of Lane-Reduction Transitions

DTFH61-13-D-00024Roadway lane-reduction transitions have long been reported to be problematic for drivers. Whether this problem is the result of a lack of understanding of lane-reduction signing or lane markings, a simple failure to comply with such markings, or other unidentified factors is unknown. This study, completed in 2019, explored driver behavior when exposed to four warning signs, two advance warning signs, and two lane line transition markings. The warning signs included traditional and new designs. Some of the new designs have currently been adopted by State departments of transportation. This study quantified driver behavior by investigating when drivers recognized that the lane would end, prepared to change lanes, and executed a lane change. The inclusion of advance warning signs resulted in earlier recognition of lane termination. Dotted-with-solid-white lane line transition markings resulted in earlier lane changes

Safety Evaluation of Permissive Flashing Yellow Arrows for Left-Turn Movements in Missouri

MoDOT project # TR202102With over a decade of crash data available since the beginning of flashing yellow arrow (FYA) use, MoDOT decided to objectively investigate the safety performance of the system. Additionally, they wished to have an accurate inventory of all FYA installations statewide, and a determination of the benefit-cost ratio of the signal system. A virtual survey of every signalized intersection on the MoDOT system revealed 841 FYA signals, and the research team either recorded dates relayed by MoDOT or estimated them from as-built plans or photo logs. A simple before and after analysis revealed FYA operation appears to reduce KABC left turn opposite direction crashes about 14 percent and left turn opposite direction O crashes approximately 18 percent when protected-permissive left turn phasing is used before and after FYA installation. Further, this analysis estimates that the lifecycle benefits of installing FYA on an intersection approach are expected to be approximately 5 to 44 times greater than the installation cost, depending on the left turn phasing used before and after FYA installation

Policies and Processes that Support Mainstreaming Transportation Systems Management and Operations

DTFH61-16-D00053The objective of this White Paper is to assist departments of transportation (DOTs) and other agencies engaged in managing and operating transportation systems in mainstreaming transportation systems management and operations (TSMO) through their policies and processes. This Paper discusses policies and processes, organized by six themes, that have helped agencies advance mainstreaming. This White Paper also explores the opportunities and challenges with mainstreaming TSMO across organizations

Calibration in Quantitative Alternatives Analysis

DTFH61-16-D-00053, T-0006In an era of emerging vehicle automation technologies and advanced traffic management strategies, traffic simulation has become an indispensable tool for giving agencies the confidence they need for adoption and implementation. Likewise the importance of calibration cannot be overstated, because there is no other way to ensure reliability of the simulation results. Current practice calls for analysts to calibrate their analytical tools to a base (or existing) condition, and then use those tools to predict performance of a future condition. However, many times these future conditions incorporate improvements that are significantly different than the base condition modeled when the analysis tool was calibrated. This can inhibit the accuracy of the calibrated model. Development of new calibration methods could allow the tools to be calibrated to data that are reflective of what the future condition will be. The Calibration in Quantitative Alternatives Analysis Primer proposes and describes the following five major components of the framework: scenarios, robustness, parameter libraries, local density, and the role of vehicle trajectories. Although developed with future conditions in mind, application of the framework would also lead to improved calibration of existing conditions. The Primer includes chapters on the framework underpinnings, case studies, and step-by-step instructions for different analysis types. To some extent the proposed framework could be applied with existing software, but future development of intermediate tools is recommended, for improved efficiency and practicality. Follow-on work will facilitate development of more detailed recommendations, parameters, model forms, and tools. The ultimate result will be more accurate traffic analyses, leading to improved trust in analysis tools, and improved transportation decision-making overall

Ensuring Cooperative Driving Automation (CDA) and Vulnerable Road Users (VRUs) Safety Through Infrastructure

693JJ319D000012Vulnerable road users (VRUs), including pedestrians, bicyclists, motorcyclists, and a variety of micromobility users, are at an increased risk for collisions, severe injuries, and fatalities relative to other road users, particularly in crowded urban environments. New transportation technologies could have both positive and negative effects on VRU safety. These new technologies include automated driving systems (ADS), which are capable of controlling vehicles with no or limited input from human drivers and cooperative driving automation (CDA), which send and receive cooperative and safety messages. The current literature review assesses the potential impact of ADS-equipped vehicles and CDA technology on VRU safety and the potential role of infrastructure in facilitating safe interactions. The review also includes a prioritized list of issues related to human factors and generated research needs, based on feedback from a panel of subject matter experts

Advancing TSMO through Organizational Structures

DTFH61-16-D00053This report applies concepts of organizational theory, specifically related to organizational structure, to explore ways in which organizational models and structural mechanisms can be used to advance transportation systems management and operations (TSMO) within departments of transportation (DOTs). It includes several case studies of organizational structures in DOTs across the Nation and looks at how DOTs have used their structures to mainstream TSMO

Evaluation of Additional Alternatives of, and Arrow Sizes for, Overhead Arrow-Per-Lane Guide Signs [techbrief]

This TechBrief discusses how complex interchanges with multiple exit lanes, including an option lane, can be confusing to navigate. Roadway signs provide navigational, lane assignment, and roadway geometry information that explain complex interchanges to drivers. Well-designed roadway signs help drivers make timely and accurate decisions. Signs that are confusing or that violate driver expectations may lead to unnecessary lane changes, sudden lane changes, and mistakes that may compromise roadway system efficiency and driver safety

FHWA Cooperative Automation Research: CARMA Proof-of-Concept TSMO Use Case Testing: CARMA Cooperative Perception Low-Level Concept of Operations

DTFH6116D00030L (TO 19-360)The Federal Highway Administration initiated the Cooperative Driving Automation (CDA) Program, formerly known as the CARMA Program, to advance the research and development of CDA to accelerate market readiness and deployment. CDA aims to improve the safety, traffic throughput, and energy efficiency of the transportation network by allowing road users and infrastructure to communicate and cooperate. CARMA cooperative perception (CP) is a feature of the CARMA Ecosystem that allows entities to share locally perceived data. CP is expected to improve perception performances of automated vehicles and CARMA Streets. The enhanced situational awareness is expected to enable more effective CDA safety and mobility applications This low-level concept of operations (ConOps) is published with the associated high-level ConOps. This low-level ConOps focuses on the system framework and requirements of the CP feature in the CARMA Ecosystem for a particular scenario involving vulnerable road users crossing in controlled conflict areas

Role of Agency Culture in Mainstreaming TSMO

DTFH61-16-D00053This White Paper aims to increase understanding of the role agency culture and cultural change can play in mainstreaming transportation systems management and operations (TSMO) and help agencies identify ways to influence their agency\u2019s culture to better facilitate mainstreaming TSMO. It presents concepts from fields such as change management, industrial/organizational psychology, and organizational development. It also incorporates examples and lessons learned from State departments of transportation (DOTs) in using cultural change to support mainstreaming TSMO