Proximity Warning System Research Articles

Quantifying Hazard Exposure Using Real-Time Location Data of Construction Workforce and Equipment

AbstractTraditional risk-assessment methods typically evaluate accident probability, exposure frequency or duration, and consequence severity, respectively, and finally determine a quantitative risk score or a qualitative risk level. The assessment process is prospective and subjective. Changing and complex construction situations impede their practical and efficient application. To assess safety risk with regard to changing site conditions in an objective and efficient way, this study proposes a quantitative model for hazard exposure assessment based on real-time location data of construction workforce and equipment, collected by a location-based proximity warning system. In contrast with traditional risk-assessment methods, the model proposed in this study combines accident probability and hazard exposure duration into a single quantitative concept—hazard exposure amount. This concept takes into account the space factor as well as the time factor of construction activities. For ease of understanding, a ...

A field experiment of workers’ responses to proximity warnings of static safety hazards on construction sites

This paper describes an experimental study of workers' responses to proximity warnings of static safety hazards on construction sites using a location-based proximity warning system named the Proactive Construction Management System (PCMS). A method of evaluating workers' responses to proximity warnings is proposed. The method consists of six variables: warning time and distance (the time and the minimum distance to a hazard when a worker receives a warning), dangerous time and distance (the time and the minimum distance to the hazard when the worker comes close to the hazard), and response time and distance (the difference between dangerous time and warning time, and the difference between dangerous distance and warning distance). Finally, whether a worker responds to a warning is evaluated against a two-second threshold and a two-meter threshold in terms of response time and distance respectively. The experiment was conducted over 17 workdays with the participation of 72 workers and resulted in 5391 warnings on a real-life construction project in Shanghai, China. The workers' responses were analyzed with respect to two factors: building trades and a-priori risk levels. The research found that workers responded to proximity warnings actively, but slightly differently across the selected building trades; carpenters had longer response latency in hazardous areas than ironworkers did, and response percentages were high for hazardous areas with high risks. The results also show evidence that PCMS has the potential to improve workers' safety performance. The limitations of the present study and future research directions are also addressed. Language: en

Use of wireless, ad-hoc networks for proximity warning and collision avoidance in surface mines

This article describes the use of wireless communication technology in an easy-to-use ad hoc mode to address concerns of timely proximity warning and collision avoidance in surface mines and also describes the design of a cloud-based logging framework for long-term vehicular traffic analysis in mines. For timely warning about approaching vehicles at large distances (10–100 m), a GPS system is integrated with Wi-Fi (IEEE 802.11a/b/p) radios in an ad hoc mode, where information about approaching vehicles is known as soon as they come into range. A communication range test is performed in an actual surface mine setting to characterise the distances at which warning can be reliably received using each of the IEEE 802.11 family of radios. A zone-based proximity warning system is designed using low power IEEE 802.15.4 radios for detecting obstacles and vehicles at much smaller distances (<10 m), and marking them into zones around the vehicle. Both the proximity warning system and the Wi-Fi-based collision avoidance system were evaluated for feasibility at an operating surface coal mine in the southern United States. Finally, the design of a cloud-based logging framework is described and can be used for long-term data collection from GPS and other sensors.

Evolution of the US Navy's collision avoidance systems (CAS) to future airborne capability environment (FACE)

The US Navy's collision avoidance systems (CAS) software product consists of five different system capabilities: ground proximity warning system (GPWS), terrain awareness warning system (TAWS), obstacle avoidance system (OAS), mid-air collision avoidance system (MCAS), and auto-recovery CAS (AutoCAS). GPWS provides directive controlled fight into terrain (CFIT) protection against fight into level or descending terrain. TAWS provides directive CFIT protection against level, descending, and rising terrain. OAS provides directive protection and situational awareness, through a display, of man-made obstacles. MCAS provides passive protection and awareness of other airborne aircraft. AutoCAS provides active protection by interacting with the avionics system to take control of the aircraft to automatically avoid impact with terrain, obstacles, and/or aircraft. For each capability, the software product provides advisories or directive aural warnings and visual indications to the aircrew. The goal is to maximize protection and minimize nuisance warnings to ensure aircrew trust the system in a dynamic tactical environment [1]. Balancing protection with nuisance warnings is done by embedding an aircraft-specific performance model into the CAS software product.

DID TECHNOLOGY IMPROVE SAFETY? AN EMPIRICAL STUDY OF CONTROLLED FLIGHT INTO TERRAIN ACCIDENTS

Aviation safety has been affected greatly by technological improvements. A series of Ground Proximity Warning Systems (GPWSs) were developed to prevent accidents during Controlled Flight into Terrain (CFIT). This study analyzed the role of GPWS (or Enhanced GPWS, EGPWS) in flight safety history to determine how effective GPWS/EGPWS was in terms of preventing CFIT. The result showed a substantial increase in CFIT accidents due to the rapid growth of aviation development. This situation improved after the mandatory installation of GPWSs in commercial aircraft. However, the legal requirement did not apply to all general aviation. Most CFIT accidents have involved general aviation aircraft that do not have GPWS/EGPWS installed on board. Thus, the mandatory requirement should apply to all civil aircraft. CFIT accidents have also been reduced considerably in developed countries whereas they remain a major issue in developing countries.

항공기 충돌 회피 경고 알고리듬 연구

항공기 사고 중에서 주요 원인 중 하나인 조종상태 지상충돌(Controlled Flight Into Terrain, CFIT)을 해결하기 위하여 대지 접근 경고 장치(Ground Proximity Warning System, GPWS)를 사용하여 항공기 아랫부분의 지형에 대해서 지형충돌 경고를 출력한다. 이러한 대지 접근 경고 장치도 적시에 경고가 발생하지 않아 많은 문제가 있었다. 본 논문에서는 비행 상태와 지형정보를 이용하여 속도가 빠르고, 고기동을 하는 전투기에 대해서 보다 효율적인 지형/장애물 충돌 회피 경고 알고리듬을 개발하였다. 이 알고리듬에는 조종사의 반응시간을 포함하여 항공기의 지연시간을 고려하였고, 일련의 검증을 통해 실제 탑재 가능한 알고리듬을 제시하였다. CFIT(Controlled Flight Into Terrain) is one of the major causes of aircraft accidents. In order to solve this problem, GPWS(Ground Proximity Warning System) is used to generate terrain collision warning using the distance between the aircraft and the underneath ground. Since the GPWS uses the vertical clearance only, it frequently generates false warnings. In this study, a terrain/obstacle collision avoidance warning algorithm was developed for fast flying and highly maneuvering fighters using the flight status and the geographic information. This algorithm condsiders the overall delay in the aircraft reactive motion including the pilot's reaction time. The paper presents a detailed logic and test methods.

Researches on Simulation and Validation of Airborne Enhanced Ground Proximity Warning System

In this paper, enhanced ground proximity warning simulation and validation system is designed and implemented. First, based on square grid and sub-grid structure, the global digital terrain database is designed and constructed. Terrain data searching is implemented through querying the latitude and longitude bands and separated zones of global terrain database with the current aircraft position. A combination of dynamic scheduling and hierarchical scheduling is adopted to schedule the terrain data, and the terrain data can be read and delete dynamically in the memory. Secondly, according to the scope, distance, approach speed information etc. to the dangerous terrain in front, and using security profiles calculating method, collision threat detection is executed in real-time, and provides caution and warning alarm. According to this scheme, the implementation of the enhanced ground proximity warning simulation system is realized. Simulations are carried out to verify a good real-time in terrain display and alarm trigger, and the results show simulation system is realized correctly, reasonably and stable.

Proximity warning and terrain modelling system based on Delaunay triangulation and surface spline interpolation

A three-dimensional real time proximity warning system (PWS) has been developed using a combination of object oriented programming techniques, open graphics library (OpenGL), global positioning system (GPS) and wireless communications networking. The main purpose of this research is to probe the application of information technologies in preventing the run-over incidents that occur frequently in large mobile equipment operations in open pit mining. The system provides three major functions: first, the system has the ability to display three-dimensional drawing exchange format (DXF) maps and has the basic map operation functions such as zoom in, zoom out, move, rotate, etc. Second, the system can show the real time positions of the trucks on the laptop installed on the truck and generate warming information when the clients are too close to each other, and then send the warming information to the client trucks. Third, the system has the ability to record the GPS positions and regenerate the surface of the mine based on the new recorded positions. So the surface maps of the mine can be updated timely. The whole system can be divided into two parts: server and clients. The clients can be any moving utilities with a GPS device installed. The server is responsible for the communication between the clients, monitors the behaviour of the clients and computes the distance between the clients in real time. Whenever the distance between two clients is less than the safe distance, warning messages will be sent to the clients and shown on the computer screens installed on the clients. The hardware of the system contains the wireless network, GPS receivers and computers installed on trucks. The system can also be applied to other industrial applications to monitor the activities of moving utilities and improve operational safety. This paper will explain the development of the system and display the field test results.

Modeling Operator Responses to Alerts

Two models were evaluated with respect to Aviation Safety Reporting System incident reports related to the Ground Proximity Warning System. These reports were examined for consistency with the first model, which was found to be invalid. A second model was developed to better explain the data, and was found to be consistent with the data and with previous results related to responses to alerting systems.

Modeling Operator Responses to Alerts

Two models were evaluated with respect to Aviation Safety Reporting System incident reports related to the Ground Proximity Warning System. These reports were examined for consistency with the first model, which was found to be invalid. A second model was developed to better explain the data, and was found to be consistent with the data and with previous results related to responses to alerting systems.

Ecological Approach to Support Pilot Terrain Awareness After Total Engine Failure

Terrain awareness enhancing avionics, such as Synthetic Vision Systems and the Enhanced Ground Proximity Warning System, have been developed to reduce the number of controlled flight into terrain accidents. The protection these systems offer, however, is far from optimal. Synthetic Vision Systems only provide pilots with perceptual data, and leave all cognition and interpretation of data to the pilot. With Enhanced Ground Proximity Warning Systems the opposite is true. Here, pilots are only confronted with compelling advisories and commands without the underlying data and rationale. This paper presents a display system, the Emergency Landing Guidance System, that visualizes the functional of surrounding terrain, adopting an ecological interface design approach. The potential benefits of this approach are demonstrated with the case of locating and approaching a suitable landing area after sudden complete engine failure. To evaluate the effect of the new display on pilot terrain awareness, an experiment was conducted in a fixed-base flight simulator. Results show that the new display supports pilot terrain awareness much better than present terrain avoidance systems, i.e., pilots better understand the meaning of the terrain in relation to their goals and constraints. However, pilots also operated more closely to the limits of performance, thereby negatively affecting the metrics for safety.

Ecological Interface Design for Terrain Awareness

Advanced terrain warning systems, such as the enhanced ground proximity warning system, and safety-enhancing displays, like the synthetic vision system, have proven to play an important role in reducing the number of controlled flight into terrain accidents. Research indicated, however, that terrain collisions may still occur for aircraft equipped with these systems. Synthetic vision allows for perception of the environment, but lacks properties to support understanding and extrapolation of the perceived data. A terrain warning system provides elementary meaning to the environment, but is not well integrated into synthetic vision displays. To further increase terrain awareness and, ultimately, eliminate terrain collisions, synthetic vision should be integrated with a terrain awareness functionality that allows the pilot to be continuously informed about how the external constraints (imposed by the terrain) relate to the internal aircraft constraints (e.g., climb performances). Based on that information, pilots can judge for themselves what an obstacle actually means to them in terms of possibilities to fly over it, and if not, what the alternatives for action are. In this article, the paradigm of ecological interface design is used to analyze the aircraft manual control task in the vertical plane and to develop a more meaningful interface for (vertical) terrain awareness. An abstraction hierarchy is presented, developed for the task of guiding an aircraft through a terrain-challenged environment. The design and experimental evaluation of a vertical situation display are discussed, enhanced with ecological overlays to increase terrain awareness.

Sound protecting headset with proximity collision avoidance protection

A proximity warning system is disposed in a sound protecting earmuff-type headset or other means of providing acoustic ear protection. The ear protector prevents the user from hearing damage from high levels of ambient sound and would otherwise generally make the user unable to hear the sounds of approaching objects like vehicles and machinery. However, an audio transducer is provided in each ear shell of the headset and is connected to a ranging device, which in the illustrated embodiment is an infrared ranging device which generates an alarm signal upon the approach of an object within a predetermined critical alarm limit. A plurality of variable alarm signals can be provided to distinguish the direction, size and speed of the approaching object. In general, the ranging device may be optical, acoustic, thermal or electromagnetic.

Evaluation of a radar-based proximity warning system for off-highway dump trucks

A radar-based proximity warning system was evaluated by researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health to determine if the system would be effective in detecting objects in the blind spots of an off-highway dump truck. An average of five fatalities occur each year in surface mines as a result of an equipment operator not being aware of a smaller vehicle, person or change in terrain near the equipment. Sensor technology that can detect such obstacles and that also is designed for surface mining applications is rare. Researchers worked closely with the radar system manufacturer to test and modify the system on large, off-highway dump trucks at a surface mine over a period of 2 years. The final system was thoroughly evaluated by recording video images from a camera on the rear of the truck and by recording all alarms from the rear-mounted radar. Data show that the system reliably detected small vehicles, berms, people and other equipment. However, alarms from objects that posed no immediate danger were common, supporting the assertion that sensor-based systems for proximity warning should be used in combination with other devices, such as cameras, that would allow the operator to check the source of any alarm.

GPS proximity warning system for at-rest large mobile equipment

Each year fatalities are caused by larger equipment running over smaller equipment and personnel. Between 1984 and 2002 there were seven fatal incidents in the USA that could have directly been prevented with the use of a proximity system with transmission lock implemented on the mobile equipment involved in each incident. These incidents resulted in the loss of lives, equipment and production time. The proximity warning and transmission locking mechanism system described here involves the development of software and hardware placed in haul trucks, service vehicles and other large mobile equipment. With the implementation of a proximity warning system (in this case based on GPS) and a transmission locking mechanism, lives could be saved and non-fatal accidents could be prevented.

Accuracy Testing of a Vehicle Proximity Warning System based on GPS and Wireless Networks

A vehicle proximity warning system is being developed using GPS and wireless local area networks to improve safety of off-highway trucks in open pit mines. After two years of research, software development, and laboratory testing, field-tests were performed at the Colorado School of Mines and in two open-pit operations to evaluate GPS accuracy and overall system effectiveness under rugged operating conditions. This paper discusses the methodology used for testing and presents a summary of results.

Preventing collisions involving surface mining equipment: a GPS-based approach

An average of three workers a year are killed in surface mining operations when a piece of haulage equipment collides with another smaller vehicle or a worker on foot. Another three workers are killed each year when haulage equipment backs over the edge of a dump point or stockpile. Devices to monitor the blind areas of mining equipment are needed to provide a warning to operators when a vehicle, person, or change in terrain is near the equipment. A proximity warning system (PWS) based on the global positioning system (GPS) and peer-to-peer communication has been developed to prevent collisions between mining equipment, small vehicles, and stationary structures. A final system was demonstrated using one off-highway haul truck, three smaller vehicles, and various stationary structures at a surface mining operation. The system successfully displayed the location of nearby vehicles and stationary structures and provided visual and audible warnings to the equipment operator when they were within a preset distance. Many surface mining operations already use GPS technology on their mobile equipment for tracking and dispatch. Our tests have shown that it is feasible to add proximity warning to these existing systems as a safety feature. Larger scale and long-term tests are needed to prove the technology adequately. A PWSs that incorporates a combination of technologies could significantly reduce accidents that involve collisions or driving over an edge at surface mining operations.

IRI Achievement Award Address: An Engineer Looks at Innovation

OVERVIEW:The development and commercial acceptance of the Ground Proximity Warning System was the culmination of years of product innovation and improvement by a small group of Honeywell engineers. Its success illustrates the soundness of such traditional innovation “rules” as “encourage your mavericks,” “get a champion,” “keep a low profile,” and “minimize the risks.”

Markov Model of Terrain for Evaluation of Ground Proximity Warning System Thresholds

Astatistical model ofterrainwasdevelopedtoestimatetheprobabilityofacontrolled eightintoterrainaccident followingaground proximitywarningsystem(GPWS)alert. The terrain model wasderived froman actual terrain database and used to create a Markov chain simulation. With this simulation the probability of terrain impact was computed as a function of terrain type and aircraft trajectory proele. Contours of collision probability were then generated and plotted against current alerting thresholds, illustrating how threshold placement maps into safety. Example results for the GPWS excessive descent rate alerting mode are provided. Following a warning and the subsequent pilot reaction delay and pull-up maneuver, the probability of collision with relatively e at terrain is less than 1 £ 10i 8 for high descent rates. In steep, rapidly changing terrain, the probability of collision following an alert increases to more than 0.01. A simple modie cation of alerting thresholds would not resolve this problem because of a resulting higher rate of nuisance alarms, as shown quantitatively by a performance tradeoff curve. Potential performance improvements through decreased response time or increased maneuvering load factor are also quantie ed.

Alarm Related Incidents in Aviation: A Survey of the Aviation Safety Reporting System Database

Today's aircraft cockpits are complex environments requiring pilots to monitor a large number of automated displays and alarm systems. A recent investigation of alarm-related incidents in Naval aircraft found high rates of alarm-related problems, particularly false and missed alarms. For the current research, we analyzed a sample of narrative accounts taken from the National Aeronautics and Space Administration's Aviation Safety Reporting System (ASRS). We categorized and tabulated the data according to alarm problem (false, missed, or other), aircraft type, avionics (alarm system), and flight phase. Our findings indicated that alarm-related incidents are still quite common in civil aircraft. Furthermore, most alarm-related incidents occur during the approach phase of a flight, and are likely to involve the Ground Proximity Warning System (GPWS) or the Traffic Collision Avoidance System (TCAS). We recommend further empirical research to understand alarm-related problems, particularly the cry-wolf effect.