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76 Various definitions exist for the technologies investigated in this report. To help the reader gain a full understanding of the significance of this report, definitions of essential terms, shown below, include descriptions of the five technology areas in this synthesis. 3-D printing: A process to create 3-D objects from a digital file by laying down successive layers of thin horizontal cross sections until the entire object is completed (Pistorius 2017). 4-D modeling: A simulation of how a facility changes over time, usually during construction. A 4-D model is a combination of the 3-D model and the additional 4th dimension of a project schedule to the model (Maier et al. 2018). Augmented reality (AR): Technology that superimposes spatially contextual information over the userâs view of the real world, providing additional data while permitting interactions with the surrounding physical environment (Campbell 2017). Automated machine guidance (AMG): A technology that uses positioning devices, singly or in combination, such as global positioning systems, total stations, and rotating laser levels, to determine and control the real-time position of construction earthwork and paving equip- ment (California Department of Transportation 2013). Building information modeling (BIM): A process that begins with creating an intelligent 3-D model and then using the model to facilitate efficient design and documentation, better coordi- nation, simulation, and visualization that gives architecture, engineering, and construction professionals the insight and tools to digitally plan, design, and construct buildings and infra- structure projects (Autodesk 2018). Dynamic message signs (DMS): Traffic control devices used for communicating traffic and work zone warnings, regulations, routing and management, and road and weather conditions information to motorists and intended to influence the behavior of drivers by providing real- time traffic-related information (Dudek and Ullman 2002). Emerging technology: A new and relatively fast-growing technology characterized by a certain degree of radical novelty, fast growth, coherence, prominent impact, and uncertainty and ambiguity (Rotolo et al. 2015). Ground-penetrating radar: A noninvasive sensing technique that captures accurate images of structures and materials such as locating underground utilities, unexplored land mines, caves, tunnels, and other unseen objects without excavation or destruction (Goulias and Scott 2015). Instrumentation and sensors: Sensors, gauges, and handheld devices used to monitor and col- lect data for specific facets and components of a highway construction project. Examples of Glossary
Glossary 77 instrumentation and sensors include remote sensing, RFID, and sensors to measure structural integrity, specifications, and environmental conditions. Interconnected technologies for construction vehicles, equipment, and tools: Technologies that enable vehicles and equipment, handheld tools, computers, and mobile devices to communicate with one another to improve safety, mobility, and performance as well as to manage the maintenance of construction vehicles, equipment, and tools (U.S. Department of Transportation 2018). Examples of interconnected technologies include AMG, e-ticketing, and tracking the location and maintenance of construction vehicles and equipment. Light detection and radar (LiDAR): An active optical remote sensing system used for measuring the distance between a surface and its sensing units using laser light pulses to create accurate 3-D models of any surface within visual sight of the sensing unit (Jeganathan et al. 2017). Real-time kinematic (RTK) system: A global positioning system that uses a base station receiver to transmit raw measurements or corrections to a rover receiver via a wireless data communica- tion link to improve the accuracy of a location in real time rather than during post processing (Rizos 2002). Remote sensing: A survey method that obtains information about the position of objects without coming into contact with the object. Examples of remote sensing include LiDAR and photo- grammetry (Maier et al. 2018). RTK rover: A mobile survey instrument with a data collector that allows the operator to deter- mine a position in real time (Maier et al. 2018). Safety technologies: Technologies used to make construction sites safer by protecting workers and traveling motorists from incidents (Nnaji et al. 2018). Example safety technologies include DMSs, VS zones, WZIA, queue detection systems, and dynamic lane merging. Unmanned aircraft vehicles (UAVs): An aircraft and its associated elements that operate with no human pilot on board. Typically, UAVs are fixed-wing, multirotor, or a hybrid of the two (Austin 2010). Unmanned aircraft systems (UASs): The elements of a UAS include the unmanned aircraft vehicle, a ground-based controller, and a communication system between the aircraft and the controller. UASs can be equipped with various components such as cameras and sensors to collect specific data (Austin 2010). Variable speed limit (VSL) zones: Speed limits that adjust on the basis of road, traffic, and weather conditions and that use electronic signs to slow down traffic ahead of congestion, work zones, and weather to smooth out flow, diminish stop and go conditions, and reduce accidents (Georgia Department of Transportation 2018). Virtual reality (VR): A computer-simulated environment that allows interaction in a realistic or physical way within that environment using an interactive 3-D model that allows a user to manipulate the model to test the impact of changes before making them in the real world (Campbell 2017). Visualization and modeling: Technologies associated with the development and use of computer- generated models to illustrate, simulate, and create aspects of highway construction projects. Examples of visualization and modeling include BIM, virtual design and construction, and AR and VR. Work zone intrusion alarm technologies (WZIA): An alert-producing mechanism with the poten- tial of securing the necessary reaction time for workers to escape in the event of a vehicle intrusion into the work zone (Teizer et al. 2015).