Roadway Workers Research Articles

Reinforcement learning-based optimal control of wearable alarms for consistent roadway workers’ reactions to traffic hazards

Recent innovations in roadway construction include work zone intrusion alert (WZIA) systems that detect traffic hazards (e.g., speeding or intruding vehicles) and raise alarms (e.g., sounds, lights) using preset attributes (e.g., volume, duration) to warn human workers-on-foot. Designing alarms raised by wearable warning devices (e.g., smartwatch) for roadway workers remains an emerging area of transportation safety research. As roadway work zones begin to adopt these novel warning systems, issues relating to alarm attributes may persist. Different individuals’ alarm preferences and alarm fatigue towards repeated exposure to constant alarm attributes can lead to decreases in worker vigilance towards traffic hazards. Reinforcement learning (RL)-based controls can adjust alarm attributes in real-time to counteract these issues, ensuring consistent worker reactions. This study proposes an RL-based approach to train agents that control alarm attributes under different reward functions that prioritise different worker safety reactions (e.g., body movement, head turn). Results show that a reward function with equal weight for each type of reaction produces an alarm agent that ensures consistent safe worker reactions to traffic hazards. Findings also inform the future development of RL-based alarms (i.e., fine-tuning) to counteract the lack of safe worker reactions observed in real-world work zones.

Identification and prioritization of key health hazards to workers in roadway construction

Abstract Although various rating systems have been developed to promote sustainable development in roadway construction, sustainability evaluation from the perspective of safeguarding workers’ health is currently lacking. Three approaches were used in the study to identify and prioritize key health hazards to workers in roadway construction, including bibliometric analysis, questionnaire survey and analytic hierarchy process (AHP). Bibliometric analysis indicates that submicron particles and polycyclic aromatic compounds are the primary concerns of researchers, and ergonomics also attracts some attention. A questionnaire survey was conducted among construction workers in China. The results suggest that the most frequently encountered occupational disorders by roadway construction workers are musculoskeletal disorders, heat stroke, respiratory health issues and hearing loss, and the most commonly encountered hazards are noise, dust, asphalt fumes, heat stress and some adverse working conditions. Perceptions on associations between the health hazards and disorders were obtained. Although there are some discrepancies between the AHP scores provided by two groups of professionals in China, the commonly agreed top occupational hazards include dust, asphalt fumes, noise, high-/low-temperature stresses and chronic injuries. The findings may be incorporated into rating systems for roadway construction to encourage the industry to adopt better practices for the well-being of workers.

Evaluation Methodology of Leader-Follower Autonomous Vehicle System for Work Zone Maintenance

Mobile and slow-moving operations, such as striping, sweeping, bridge flushing, and pothole patching, are critical for efficient and safe operation of a highway transportation system. However, reducing hazards for roadway workers and achieving a safer environment for both roadway maintenance operators and the public is a challenging problem. In 2017 alone, a total of 158,000 vehicle crashes occurred in work zones in the U.S.A., accounting for 61,000 injuries. The autonomous truck-mounted attenuator (ATMA) vehicle, sometimes referred to as an autonomous impact protection vehicle (AIPV), offers a promising solution to eliminate injuries to roadway maintenance workers and the public. This paper presents the evaluation methodology for the ATMA system, as well as the outcomes of field testing in Sedalia, Missouri. To the best of the authors’ knowledge, this is the first academic research to focus on ATMA. The ATMA system is first reviewed, followed by an introduction to the field testing procedures that includes descriptions of test cases and data collected, and their format. An analysis methodology is then proposed to quantitatively evaluate the system’s performance, and statistical models and hypothesis testing procedures are developed and presented. The numerical analysis results from real-world field testing under a controlled environment are presented, and the ATMA system’s performance is summarized. This paper can serve as a reference for transportation agencies that are interested in deploying similar technologies or for academic researchers to assess characteristics of autonomous vehicles and to apply knowledge gained in transportation modeling and simulation practices.

Constructing Costa Rica’s Inter-American Highway and Building U.S. Empire: Social, Economic, and Political Change at the Local Level, 1941-44

Before 1944, countless Costa Rican travelers perished on the narrow rocky trail that traversed the 3,491 meter Cerro de la Muerte. Undaunted, between 1941 and 1944 U.S. engineers and Costa Rican workers built a 49-mile segment of the Inter-American Highway that conquered the Cerro. For many, both in the countryside and in the city, the roadway was a symbol of progress and modernization that inspired an image of the San José-centered state as a benevolent patriarch and the United States as a wealthy and generous Good Neighbor. The roadway, however, also had its detractors, namely communist labor organizers, who saw the project as a symbol of U.S. imperial exploitation that threatened Costa Rican sovereignty and harmed workers. The Communist press and labor organizers sought to mobilize highway workers and popular discontent against the roadway, but their efforts were largely ineffective. Indeed, ultimately, roadway workers, their families, and neighbors were grateful for the increased transportation and communication the roadway furnished their communities and the well-remunerated labor opportunities this transnational infrastructure provided. In sum, the roadway’s detractors failed to foster negative perceptions of the roadway as a symbol of the exploitative nature of the U.S. Empire on the ground.

Time of day effects on railroad roadway worker injury risk

IntroductionThe purpose of this study is to examine how time of day affects injury risk of railroad maintenance of way employees and signalmen (roadway workers). Railroads reported 15,654 serious roadway worker injuries between 1997 and 2014. Roadway workers primarily work outdoors on or near railroad tracks and frequently encounter hazardous conditions. To avoid closing an active rail line during peak hours, railroads sometimes require roadway workers to work at night. Previous studies of roadway worker injury have not adequately accounted for exposure to time of day effects, nor have they investigated the human factors issues contributing to roadway worker injury. MethodThe Federal Railroad Administration (FRA) database of injury reports provided data for circadian rhythm models of the odds of fatal and nonfatal injuries. The FRA database and fatal injury investigation reports also permitted an analysis of the circumstances and the human factors issues associated with injuries that occur at different times of day. ResultsOdds of injury increased during nighttime work. The odds of nonfatal injury for both roadway worker crafts rose above 9:1 in the early morning hours. The relative odds of a fatal injury also increased significantly at night. A human factors analysis suggested that during all three shifts most nonfatal injuries involve workload, but workload was not identified as a factor in fatal injuries. ConclusionsNighttime work is more hazardous for roadway workers than daytime work. Several factors related to fatigue and other conditions appear to increase the risk of injury during the outdoor, nighttime work required of roadway workers. Practical applicationFor practical reasons, nighttime roadway work is sometimes unavoidable. Therefore, new practices for nighttime work must be developed to adequately address fatigue and protect roadway workers from harm.

Electroluminescent Materials Can Further Enhance the Nighttime Conspicuity of Pedestrians Wearing Retroreflective Materials.

We investigated the nighttime conspicuity benefits of adding electroluminescent (EL) panels to pedestrian clothing that contains retroreflective elements. Researchers have repeatedly documented that pedestrians are too often not sufficiently conspicuous to drivers at night and that retroreflective materials can enhance the conspicuity of pedestrians. However, because retroreflective elements in clothing are effective only when they are illuminated by the headlamps of an approaching driver, they are not useful for pedestrians who are positioned outside the beam pattern of an approaching vehicle's headlamps. Electroluminescent materials-flexible luminous panels that can be attached to clothing-have the potential to be well suited for these conditions. Using an open-road course at night, we compared the distances at which observers responded to pedestrians who were positioned at one of three lateral positions (relative to the vehicle's path) wearing one of two high-visibility garments. The garment that included both EL and retroreflective materials yielded longer response distances than the retroreflective-only garment. This effect was particularly strong when the test pedestrian was positioned farthest outside of the area illuminated by headlamps. These findings suggest that EL materials can further enhance the conspicuity of pedestrians who are wearing retroreflective materials. EL materials can be applied to garments. They may be especially valuable to enhance the conspicuity of roadway workers, emergency responders, and traffic control officers.

On-Duty Struck-By Crashes

On-duty struck-by crashes are defined as traffic crashes that involve police officers, roadway workers, firefighters, and emergency medical technicians–first responders who are hit by a motorist while on duty assisting at an incident or in a work zone. The objective of this research was to summarize and analyze struck-by crashes on the basis of Wisconsin crash data. Crash data from 2000 to 2010 on Wisconsin's state trunk network were selected from the WisTransPortal database. Data reduction included several filtering steps and manual identification; 265 crashes were identified as struck-by crashes, and their characteristics and contributing factors were analyzed. Responder and worker struck-by crashes were analyzed separately because of their different characteristics, and all state trunk network crashes from 2000 to 2010 were used as a comparison group. Results showed that for responder crashes, police officers were the predominant victim. A large proportion of responder crashes occurred on rural Interstate highways. Speeding or driving too fast for conditions was the key driver factor that led to struck-by crashes, and adverse roadway and weather conditions were the most significant environmental factor. Most emergency responder struck-by crashes occurred when responders were assisting at traffic crashes. However, flaggers hit by surrounding traffic accounted for approximately half of all worker struck-by crashes. Worker crashes were uncorrelated with adverse weather, roadway, or lighting conditions. Inattentive driving was the most significant contributing factor. These results provide the basis for countermeasures to reduce struck-by crashes involving emergency responders and roadway workers.

Pedestrians’ estimates of their own visibility: A simple and effective computer-based technique

IntroductionResearch has shown that both pedestrians and drivers drastically overestimate pedestrians' nighttime visibility (NHSTSA, 2008a, 2008b; Owens & Sivak, 1996) and fail to appreciate the safety benefits of proven conspicuity aids. One solution is educational intervention (Tyrrell, Patton, & Brooks, 2004); however, the on-road assessment of its effectiveness is expensive and time consuming. MethodExperiment One introduces a computer-based alternative to the field-based approach, successfully replicating the previous study's trends among 94 students who either receive or do not receive an educational lecture. Experiment Two utilizes the simulation's portability to determine if professional roadway workers have a more accurate understanding of pedestrian conspicuity than students. Results: Results among 88 workers show they do not significantly appreciate the advantages of effective retroflective material configurations or vehicle headlamp settings, for example, any better than non-lectured students in Experiment One. Impact: The study's results demonstrate the need for education among all pedestrians and the benefits of efficient testing methods.

Using biological motion to enhance the conspicuity of roadway workers

This study examined whether the conspicuity of road workers at night can be enhanced by distributing retroreflective strips across the body to present a pattern of biological motion (biomotion). Twenty visually normal drivers (mean age=40.3years) participated in an experiment conducted at two open-road work sites (one suburban and one freeway) at night-time. At each site, four road workers walked in place wearing a standard road worker night vest either (a) alone, (b) with additional retroreflective strips on thighs, (c) with additional retroreflective strips on ankles and knees, or (d) with additional retroreflective strips on eight moveable joints (full biomotion). Participants, seated in stationary vehicles at three different distances (80m, 160m, 240m), rated the relative conspicuity of the four road workers. Road worker conspicuity was maximized by the full biomotion configuration at all distances and at both sites. The addition of ankle and knee markings also provided significant benefits relative to the standard vest alone. The effects of clothing configuration were more evident at the freeway site and at shorter distances. Overall, the full biomotion configuration was ranked to be most conspicuous and the vest least conspicuous. These data provide the first evidence that biomotion effectively enhances conspicuity of road workers at open-road work sites.

Incremental Train Control System

In 1995, GE started development of the incremental train control system (ITCS) for Amtrak to use on its Michigan corridor between Detroit and Chicago. The primary objective for ITCS was to allow Amtrak passenger trains to operate at 110 mi/h intermixed with freight traffic. To achieve this objective, the traditional wayside signal system would be enhanced with a positive train control (PTC) system to enforce the wayside signal indications (train movement authorities) and operating speed limits. Additionally, the highway-rail grade crossings had to provide the required warning time for trains operating at higher speeds than for what the crossings had originally been designed (79 mi/h). ITCS in Michigan is a fail-safe (vital) positive train control system that overlays the existing signal system for improved safety and provides a cost-effective solution for high-speed train operation. ITCS meets the requirements for PTC, a train control system recently mandated by the U.S. federal government to prevent trainto-train collisions, over-speed derailments, incursions into roadway worker zones, and movement over a misaligned track switch.

Trust-based secure Positive Train Control (PTC)

Positive Train Control (PTC) is a wireless control system ensuring railroad safety by enforcing train separation, speed enforcement, roadway worker protection and other safety functions. Due to shared trackage rights over each-other’s tracks in North America, company A’s trains must be safely operated by company B’s crew on company C’s tracks, requiring different PTC systems to securely interoperate with each other. We propose using a trust management system with certificates and over the air re-keying (OTAR) as a security framework to ensure secure interoperation. Preliminary estimates show that our solution meets timing needs of PTC.

Key management requirements for PTC operations

Positive train control (PTC) is an electronic system that enforces activities such as train separation, speed enforcement, and roadway worker protection essential to operate railroads safely and efficiently. Vehicular ad-hoc networks (VANETS) provide distributed real time communication of traffic hazards and road conditions among vehicles in a radio line of sight. Communicating PTC VANET systems offer the potential to reduce highway rail intersection (HRI) collisions by communicating train movement information to highway vehicles. For this to occur, different PTC systems must securely interoperate with each other. This outlines a PTC security framework utilizing using a certificate based trust management system and over the air re-keying (OTAR) to support interoperation.

Shared Situation Awareness as a Contributor to High Reliability Performance in Railroad Operations

Cooperative strategies of individuals within a distributed organization can contribute to increased efficiency of operations and safety. We examine these processes in the context of a particular work domain: railroad operations. Analyses revealed a variety of informal cooperative strategies that railroad workers have developed that span across multiple railroad crafts including roadway workers, train crews, and railroad dispatchers. These informal, proactive communications foster shared situation awareness across the distributed organization, facilitate work, and contribute to the overall efficiency, safety, and resilience to error of railroad operations. We discuss design implications for leveraging new digital technologies and location-finding systems to more effectively support these informal strategies, enhance shared situation awareness, and promote high reliability performance.

Fostering Shared Situation Awareness and on-Track Safety Across Distributed Teams in Railroad Operations

Cooperative strategies of individuals within a distributed organizational structure can contribute to increased efficiency of operations and safety. We describe selected results of a cognitive task analysis that examined the cognitive and collaborative demands and activities of railroad roadway workers. The findings highlight the informal cooperative strategies that railroad workers have developed across distributed teams consisting of roadway workers, train crews, and railroad dispatchers that foster shared situation awareness and enhance on-track safety. We discuss design implications for leveraging new digital technologies and location finding systems to more effectively support these informal strategies to improve efficiency and enhance on-track safety are discussed.