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6 This review is broken into three sections. The first discusses the emphasis of e-Construction within the EDC during two iterations of the programâEDC-3 (2015â2016) and EDC-4 (2017â2018). EDC-3 activities revolved around expanding the use of e-Construction, specifically moving toward paperless workflows. Building on this theme, EDC-4 shifted its focus slightly to e-Construction and Partnering, emphasizing the important role e-Construction technologies can play in forming strong partnerships between transportation agencies and private industry stakeholders. Several peer exchanges were held in conjunction with EDC-4, the outcomes of which are summarized here. These summaries are included because they are valuable for understanding how agencies have integrated e-Construction into business opera- tions as well as best practices for implementation. Further, understanding initiatives that are promoting the use of technology in highway construction provides foundational knowledge given the lack of published work on e-ticketing. The second portion of the literature review briefly introduces technologies that can be integrated into solutions for tracking and monitoring the location of bulk materials on high- way construction projects from stockpiles, plants, and warehouses to jobsites. Academic literature was examined, along with other research publications and recent trends in the construction industry, to select technologies for inclusion in the discussion. It highlights (1) radio frequency identification (RFID), (2) GPS, (3) bar codes, (4) unmanned aerial systems (UAS; i.e., remotely piloted drones), and (5) e-ticketing. The search encountered a few other technologies such as ultra-wideband (UWB), smart cards, and near field communications (NFC) in the literature; however, they remain uncommon and therefore are not a focus of the review. The third portion of this review spotlights research that has explicitly proposed systems that leverage these technologies in varying combinations to monitor the transport of bulk materials within construction sites or between suppliers and jobsitesâor which plausibly could be used to do so. Although there is a less expansive body of literature focused on the use or performance of these technologies in the context of tracing bulk material movements (e.g., asphalt, concrete, aggregate, millings), solid examples exist. It thus emphasizes use cases relevant to transportation industry stakeholders. Several private-sector firms have introduced proprietary systems that take advantage of one or more of the aforementioned technologies to track the conveyance of bulk materials. As is evident in the architecture and logic of these systems, their conceptual foundations can indeed be discerned in the academic research publi- cations outlined. The search also describes unique or proprietary approaches to tracking bulk materials that have been tried out by transportation agencies. Doing so illuminates the latest technological advances and use cases; however, the inclusion of a particular system should not be construed as an endorsement. C H A P T E R 2 Literature Review
Literature Review 7 2.1 EDC and e-Construction The EDC program began in 2009 as a joint venture between the FHWA and AASHTO, and focuses on deploying new innovations, with the goal of accelerating highway project delivery in an economically responsible manner (Landers, 2015; Federal Highway Administration, 2018c). Aside from increasing the spread of innovations, a primary goal of EDC is to encourage produc- tive risk taking at public agencies, which can be hesitant to embrace new technologies or prac- tices not yet proven in the field. One risk EDC promoted for STAs was a move from reliance on paper documentation. Recognizing the use of paper documentation to administer highway projects made logis- tics, scheduling, and communications increasingly fraught and untenable; FHWA introduced e-Construction as an innovation during EDC-3 (2015â2016). In making this selection, the agency observed that paper documentation is cumbersome; is expensive to create, process, and store; and hampers communication between project stakeholders. For EDC-3, FHWA broadly conceived of e-Construction as âthe collection, review, approval, and distribution of construction contract documents in a paperless environmentâ (Federal Highway Administra- tion, 2015). The initiative sought to deploy readily available and already-proven technologies, including digital electronic signatures, electronic communications, secure file sharing, version control, mobile devices, web-hosted data archival and retrieval systems, and RFID tags for tracking the location of resources. In advocating for the use of e-Construction, FHWA cited the positive experiences of several STAs (e.g., Michigan and Florida DOTs) as well as its ability to improve the quality, efficiency, environmental sustainability, and productivity of the construction industry. The baseline report found that as of January 2015, 16 state agencies had institutionalized the use of e-Construction or were at the assessment or demonstration stages of deployment (Figure 2.1). By the end of EDC-3, FHWAâs goal was to increase the number of states at one of these three stages to 36 and dramatically expand the number of states in which e-Construction was institutionalized (Federal Highway Administration, 2015). While EDC-4 (2017â2018) retained e-Construction as an innovation, the emphasis shifted to e-Construction and Partnering (eCP). Partnering is a project management technique where transportation agencies, contractors, and other stakeholders form a single team whose foun- dation is built on shared trust (Federal Highway Administration, 2017a). Establishing a team helps to mitigate risk, enhance communication, minimize waste, quickly resolve issues, and fulfill project objectives. The EDC-4 baseline report found that transportation agencies made significant progress incorporating e-Construction into their business practices. By the conclu- sion of EDC-3, 35 states had reached the institutionalized, assessment, or demonstration stages, which indicates the FHWA nearly met the goals advanced at the beginning of EDC-3 (Federal Highway Administration, 2017b). Wanting to sustain this momentum throughout EDC-4, the agency wanted to continue expanding the penetration of e-Construction to nearly all states, including reaching institutionalized status in 21 states (Figure 2.2) (Federal Highway Admin- istration, 2017b). However, there was less widespread use of e-Construction to strengthen partnering on construction projects. The FHWA saw this as a troubling gap, believing that partnering arrangements would become less effective without integrating e-Construction prac- tices. Accordingly, the FHWA hoped to achieve the institutionalization of eCP in 14 states while moving eight additional states to the assessment stage. FHWA cited a number of benefits associated with eCP (Federal Highway Administration, 2017a; Federal Highway Administration, 2017b). First, it provides greater transparency and gives project stakeholders the means to quickly resolve problems and minimize disputes. Signifi- cant time savings can also be realized through eCP by letting inspectors perform data collection and submit reports electronically. Likewise, project managers can more efficiently administer
8 Electronic Ticketing of Materials for Construction Management Figure 2.1. Status of e-Construction implementation reported in the EDC-3 baseline summary (Federal Highway Administration, 2015). Figure 2.2. Status of e-Construction implementation reported in the EDC-4 baseline summary (Federal Highway Administration, 2017b).
Literature Review 9 projects when they go paperless. Third, eCP can improve the safety of jobsites by reducing the amount of time inspectors are exposed to worksite hazards; the lack of paper documentation can also bolster safety because project stakeholders no longer have to carry physical records between project sites and offices. In relying on electronic documents, eCP trims project costs, fosters more productive communication, and lowers the number of change orders. Building stronger communication among stakeholders also builds an environment that values respect and mutual trust. Last, eCP supports better coordination and collaboration by increasing the transparency of workflows and giving stakeholders rapid access to information. FHWA outlined a multipart innovation goal in its EDC-4 work plan (Federal Highway Administration, 2017b). A primary goal was to speed up the adoption of e-Construction and forge new standards that would root construction-related project management, communica- tion, and workflows in e-Construction practices. Further, FHWA envisioned growing the use of sophisticated technology applications across state agencies. This included having inspec- tors adopt survey-grade positioning data on tablets as well as real-time data processing. At the regional summits held in the run-up to EDC-4, attendees emphasized the importance of pro- moting the use of innovations like e-ticketing, remote video monitoring, and seamless data integration across project life cycles. In particular, FHWA viewed EDC-4 as an opportunity to promote e-ticketing to states classified as in the advancing stage. Another area in which the agency identified significant potential of e-Construction was in materials management and asset management, believing its use could produce significant cost savings. Throughout 2018, FHWA helped organize and convene several peer exchanges that brought together STAs to discuss their experiences with eCP and future ambitions (Federal Highway Administration, 2018b; Federal Highway Administration, 2019a; Federal Highway Administra- tion, 2019b). A peer exchange held in Indiana included STAs from the Indiana DOT (INDOT), Oregon DOT (ODOT), Pennsylvania DOT (PennDOT), Utah DOT (UDOT), and Wisconsin DOT (WisDOT) (Federal Highway Administration, 2018b). At INDOT, the current emphasis is on imagining e-Construction more expansively than as just paperless workflows, viewing it instead as providing the means to transform decision making into a data-driven process. Agency personnel are working to integrate digital data into every aspect of project delivery, including the adoption of three-dimensional (3-D) models as the legal contract; combining model information with construction inspection applications; developing metrics to calculate return on investment for e-Construction; and identifying new technologies to track material delivery, placement, and conditions. For the latter priority, the agency is interested in determining whether e-ticketing is beneficial for tracking materials and monitoring quantities when laying hot mix asphalt (HMA). INDOT staffers also shared challenges the agency has encountered in shifting toward an operational model founded on data-driven decision making, such as working with 3-D models, nurturing an agency culture that embraces change, and investing in change management. Of the agencies participating in the peer exchange, only PennDOT had experience with e-ticketing for bulk materials (see Chapter 4 for additional details). Looking at returns on investment, ODOT has realized significant qualitative and quantitative benefits from mobile mapping systems and 3-D engineered models. The key qualitative benefits have been acceler- ated project delivery and higher quality products while the agency has also accrued millions in savings. Representatives from WisDOT observed their agency has seen meaningful returns on investment from cloud-based plan review and documentation, including a reduction in change orders. Moving forward, stakeholders from all agencies agreed on the importance of devising strategies to integrate disparate e-Construction technologies to facilitate seamless workflows as well as clearly defining why electronic deliverables are important and how they should be used. A peer exchange hosted by the Alabama Department of Transportation (ALDOT) brought together agency staff from Minnesota DOT (MnDOT), Missouri DOT (MoDOT), ODOT, and
10 Electronic Ticketing of Materials for Construction Management UDOT to explore how organizations can benefit from UAS (Federal Highway Administra- tion, 2019a). Agencies have identified a growing number of use cases for UAS technologies, such as monitoring pavement to identify areas where delamination is occurring, documenting work zone traffic control, and measuring pay item quantities (e.g., earthwork and stockpile volumes, pay items based on area or linear metrics). Although UAS technologies may be sufficient for quantifying bulk materials in some circumstances, such as measuring earthwork quantities along short roadway segments, it may not be appropriate for final pavement quan- tities, such as where roadway segments are long enough that it is beyond the capabilities of visual-line-of sight flight. Other key advantages of UAS technologies are opening up access to complex terrain and structures, improving documentation through high-resolution imagery, and bolstering the efficiency of agency workflows through automated data collection and feature extraction. For organizations interested in developing a UAS program, agency representatives noted that it is critical to develop standardized procedures to ensure consistency, repeatability, and predictability. Also important for successful implementation is fostering an agency culture in which continuous learning is valued, as this can help key personnel stay informed on new advances as well as changes in regulations affecting UAS deployment. A third peer exchange between the Virginia DOT (VDOT) and PennDOT focused on mobile technologies (Federal Highway Administration, 2019b). Virginia requested the forum because of its recent decision to orient mobile strategies around readily available commercial-off-the-shelf applications; it wanted to glean information from PennDOT on its experience implementing mobile technologies. Despite getting an early start with e-Construction by adopting e-bidding and advertising in 2001, issues with funding and stakeholders have prevented a full rollout of e-Construction initiatives at VDOT. The agency wants to greatly expand its e-Construction footprint over the coming 2 to 3 years, however, with a focus on using mobile technologies to foster better inspection and testing, construction management, and acceptance and closeout processes. Virginia has funded research to assess the performance of mobile applications for documenting project site activities, accessing electronic plans, and collaborating with stake- holders. Because PennDOT is covered more extensively through an in-depth case example in Chapter 4, its activities are only briefly sketched out here. The agency relies on its Engineering and Construction Management System (ECMS) to support actions from bidding through construction closeout. PennDOT has done in-house development of its mobile computing solutions, which tie in with ECMS. Mobile applications reduce the use of paper, lessen the amount of duplicative data entry, and take full advantage of automated workflows. Cost-benefit analyses presented by PennDOT indicate the agency has saved over $60 million through its e-Construction pro- grams. Several key takeaway messages were elaborated based on the experiences of PennDOT and VDOT. First it is critical for an agency to develop a roadmap that imagines the status of e-Construction and mobile technologies in 5 to 10 years. Also, beginning small and slowly building a foundation is the surest way to achieve whatever goals are identified. One possible strategy for agencies to consider (and one adopted by PennDOT) is to use an agile method for developing new applications, which is an approach to project management that prioritizes small, continuous improvements. When first starting out, it is critical to focus on developing intuitive processes and workflows that will stimulate personnel to embrace new technologies, and which are also defined by their simplicity and produce consistent results. 2.2 Materials Tracking Technologies Technological advances over the past 30 to 40 years have resulted in increasingly sophisti- cated automated methods of tracking items ranging from packages, retail goods, and vehicles to concrete members, steel beams, and bulk materials. Construction industry stakeholders have gradually embraced an array of technologies such as RFID, unmanned aerial vehicles (UAVs;
Literature Review 11 also referred to as UAS or drones), GPS, advanced image processing, light detection and ranging (LiDAR), bar codes, smartphones, and various software apps, seeing in their use the opportu- nity to shorten project durations, increase productivity, reduce manual labor and data entry, foster greater transparency, and support better record keeping (Taneja et al., 2010; El-Omari and Moselhi, 2011; Zhou and Gheisari, 2018; Nipa, Rouhanizadeh, and Kermanshachi, 2019). Likewise, the highway construction industry, as part of a sweepingly ambitious push to automate more aspects of the construction process, has aggressively implemented many of these tech- nologies (Federal Highway Administration, 2018a). The pace of adoption will only accelerate in the coming years. The purpose of this section is to describe technologies used to track the whereabouts of materials on construction projects. For each technology, a concise description is provided along with documented use cases and salient references. The review is not intended to be exhaustive; its aim is to highlight important technologies that have been or could be used in systems for tracking and monitoring bulk materials. The following sections provide details on systems that have been designed or implemented for this purpose. 2.2.1 Bar Codes Bar codes come in one-dimensional (1-D), two-dimensional (2-D), and 3-D formats. Scanning bar code data is much faster than manually entering data, bolsters data accuracy, and makes the data handling process more secure (Lee and McCullouch, 2008). A 1-D bar code is linear and consists of parallel lines and spaces that are vertically oriented. The Universal Product Code (UPC) is probably the most familiar iteration of a 1-D bar codeâfound on practically any item that can be purchased, they are composed of a 1-D bar code plus a 12-digit number that encodes information about the brand owner and item, including a check digit. The 2-D bar codes (also referred to as matrix codes) have an overall square shape, inside of which is a unique arrangement of rectangles; their storage capacity is significantly greater than 1-D bar codes. A common example of a 2-D bar code is the now-ubiquitous quick response (QR) code, which can be scanned with a mobile device or camera; they can redirect users to websites, store personal information, and are commonly used in advertising. Last, 3-D bar codes resemble 2-D bar codes; however, the internal rectangles extend to varying heights, which are measured and interpreted by a scanner (Nikolow, 2012). They are less common than 1-D or 2-D bar codes. Bar codes have been used in the construction industry to facilitate docu- ment management (Shehab, Moselhi, and Nasr, 2009; Lee et al., 2018), integrate with RFID to improve data acquisition (Moselhi and El-Omari, 2006), and manage materials and equip- ment (Lee et al., 2013). Recently the Iowa DOT piloted a project in which concrete deliveries were tracked with the aid of QR codes affixed to the dashboards of haul trucks (Shepard, 2017; see Chapter 4). 2.2.2 RFID RFID takes advantages of electromagnetic signals to capture and transmit data (Jaselskis and El-Misalami, 2003). RFID systems generally have two components: an RFID tag and an RFID reader. The tag contains a microchip that stores data and an antenna for communicating data. Three types of tags are available. Passive tags rely on the electromagnetic field produced by the RFID reader for their activation and have a very long service life but operate over a relatively short range. Active tags include a built-in power source and typically store more data and have the longest range but are most costly and have a limited service lifeâup to 10 years in most cases (Domdouzis, Kumar, and Anumba, 2007; Lu, Huang, and Li, 2011). Semi-passive tags have an internal power supply that is flipped on when it receives a signal; they are also more expensive than passive tags, have a shorter service life than active tags, and have a moderate range (Valero, Adán, and Cerrada, 2015). Microchips within tags are read-write; read only; or write once, read
12 Electronic Ticketing of Materials for Construction Management many (WORM). RFID readers also have an antenna and communicate data to and receive data from tags. Several RFID frequencies exist, with each being used for a different suite of applica- tions. Unlike bar codes, RFID systems do not require line of sight for scanning (Moselhi and El-Omari, 2006). Although RFID tags are more durable than bar codes, they are also more expensive to produce or purchase. RFID systems have found a number of uses in the construction industry, including the tracking of pipe spools and steel members, observing the movements of items on construction sites, locating underground assets, tracking materials such as asphalt from suppliers to project sites, performing material control, and inventorying equipment and workers (Moselhi and El-Omari, 2006; Domdouzis, Kumar, and Anumba, 2007; Kasim, Latiffi, and Fathi, 2013; Valero, Adán, and Cerrada, 2015). 2.2.3 GPS GPS is a satellite-based navigation system that can be used to determine the location of objects. GPS satellites broadcast radio signals that include their location, status, and the time. When a GPS receiver picks up these radio signals, it calculates its distance from a satellite. Once a GPS receiver has assessed its distance from four satellites, it can derive its location on earth in three dimensions (National Coordination Office, n.d.). Real-time kinetic (RTK) positioning is often used in the construction industry, particularly for surveying applications as it can provide centimeter-level accuracy. It uses a satellite navigation method to get highly accurate location information from GPS. A number of GPS-based systems have been proposed or implemented to facilitate the identification and tracking of materials on construction sites; some systems have combined RFID and GPS technologies to accomplish this (Navon and Shpatnitsky, 2005; Song, Haas, and Caldas, 2006; Razavi and Haas, 2011; Sardroud, 2012). GPS, as well as RFID and wireless internet connections, can facilitate materials tracking through the establishment of geofences. Geofences can be set up around different locations (e.g., boundary of supplier facility, entry and exit points of construction sites) and leveraged to record the movements of haul trucks and other vehicles. 2.2.4 Advanced Imaging and UAVs/UAS Many STAs, consultants, and contractors are incorporating UAS and UAVs (commonly referred to as drones) into workflows to improve the efficiency and safety of activities such as bridge inspections (Duque, Seo, and Wacker, 2018; Khaloo et al., 2018), monitoring jobsite safety (De Melo et al., 2017), and improving construction project management (Zhou, Irizarry, and Lu, 2018; Greenwood, Lynch, and Zekkos, 2019). Zhou and Gheisari (2018) thoroughly reviewed the implementation of UAS in the construction industry. When combined with LiDAR, infrared cameras, sensors, and other advanced imaging technologies, UAVs can help generate precisely detailed maps of project sites and detailed 3-D models of buildings, structures, and even stockpiles (e.g., Arango and Morales, 2015). Researchers have also devised methods of estimating stockpile volumes through 2-D images and various analytical techniques (Shehab, 2009; Christie et al., 2015). UAVs and RFID technologies have been paired on an experimental basis to determine the feasibility of using them in combination for materials tracking (Hubbard et al., 2015). Because UAVs and remote sensing technologies are best suited to monitoring sta- tionary objects and features, they are probably not the optimal solution for dynamically tracking materials from the point of production to construction sites. 2.2.5 e-Ticketing Traditionally, materials deliveries have been documented through the use of paper tickets. This unwieldy process is inefficient, potentially endangers workers and inspectors, often
Literature Review 13 requires some form of manual data entry, and can delay invoicing and payment. e-Ticketing solves these problems through paperless administration. Information that would otherwise be summarized on a printed document (e.g., batch properties, tonnage, delivery times, asphalt temperature, and signatures) are stored and transmitted electronically (Newcomer et al., 2019; Nipa, Rouhanizadeh, and Kermanshachi, 2019). Eliminating paper documents fosters improved safety and greater efficiency, reduces environmental waste, protects against the damage or loss of tickets, and improves project management. Several of the case examples presented in Chapter 4 highlight the implementation of e-ticketing in agency settings. For example, as the Iowa DOT case example demonstrates, when coupled with GPS and GIS, e-ticketing can support dynamic, real-time tracking of materials. Much of the adoption of e-ticketing can be contributed to the safety benefits. Removing the manual ticket collection process eliminates the hazard of climbing on a truck near active traffic to obtain the paper ticket from the driver. No significant research studies have reported on e-ticketing in detail to date. 2.3 Systems for Monitoring the Transportation and Inventory of Bulk Materials Over the past 25 years, researchers have proposed and experimented with a variety of systems to track materials as they are moved from the point of production to construction sites. Tech- nologies like RFID, GPS, and e-ticketing often serve as the linchpins of these systems. Building on the concepts that were described previously, this section highlights examples of systems that have been developed to track bulk materials, or which could be used for this purpose despite not being expressly designed with this goal in mind. Certainly, the innate characteristics of bulk materials pose a number of logistical and procedural challenges for tracking them. Although a technology like RFID tags or GPS units can be used with relative ease with dis- crete elements (e.g., steel beams, concrete members), they are less well adapted to viscous or flowable materials. Indeed, affixing an RFID tag to a steel beam is a straightforward procedure. Conversely, RFID tags cannot be fitted directly to a batch of aggregate or asphalt. Likewise, a GPS receiver cannot be attached to concrete inside the drum of a concrete mixer. These may seem like intuitive observations, but they are important to keep in mind as most of the systems reviewed in this section do not track the materials per se. Primarily, they track the vehicles or containers in which the materials are being transported. Readers will detect a common system architecture as they gloss over the examples. The following paragraph offers a thumbnail sketch of a basic materials tracking system. RFID tags are affixed to haul trucks at a plant, and information on a batch of materials is downloaded to the tagâsystems designed more recently have used bar codes and QR codes in a similar manner. RFID readers at the plant and construction site record when trucks enter or leave the premises. GPS is frequently used to monitor vehicle location and movements. New systems may rely entirely on GPS as well as the establishment of geofences around the perim- eters of plants, scales, jobsites, and other features of interest to precisely record where and when haul vehicles are at different locations. Information for each batch of material, including any e-tickets, is transmitted to and stored in a centralized database. Records generated during this process can be used to prepare invoices and serve as documentation that materials were deliv- ered to a construction site. This sketch intentionally omits the nuances of various systems and how frameworks developed for tracking bulk materials have evolved conceptually and in their implementation. The rest of this section presents, in roughly the chronological order they were developed, systems used to track bulk materials. Adopting this sort of genealogical approach helps readers better appreciate how thinking on materials tracking has changed since the 1990s and some of the common problems early adopters have confronted.
14 Electronic Ticketing of Materials for Construction Management Jaselskis et al. (1995) proposed three applications for using RFID in the construction industry: (1) monitoring concrete deliveries; (2) tracking the activities of workers and equipment; and (3) managing critical materials. Despite the piece being written in the mid-1990s, it is noteworthyâand therefore merits detailed treatmentâbecause it anticipates quite accurately contemporary trends in e-Construction, down to the types of systems and methods used to trace the locations of vehicles and materials. The summary focuses on the system for managing concrete deliveries (Figure 2.3). After a concrete supplier receives a buyerâs order electronically, a batch plant supervisor reviews the order and makes truck assignments. Concrete mix require- ments and ID numbers for the assigned trucks are sent to a computer at the batch plant. Then, a radio frequency (RF) scanner is placed in the loading area; its purpose is to read the RFID unit attached to a truck, verify its ID number, and ensure the truck ID matches its assignment. Next, specifications for the concrete mix, admixtures, loading time, and delivery are programmed into Figure 2.3. RFID-based tracking system proposed by Jaselskis et al. (1995).
Literature Review 15 the RFID unit. At this point, a truck is ready to leave the plant. Upon its departure, a centralized computer at the destination jobsite receives notification that the truck is en route. The notifica- tion also contains information about the truck ID, concrete mix specification, and departure time. As the truck travels to the jobsite, data are recorded on the number of mixing revolutions, truck speed, and truck location (if the vehicle is equipped with GPS). When the truck arrives at a jobsite, a scanner reads the RFID unit and transmits information to the centralized computer, the job of which is to confirm that the number of revolutions and mix time align with specifica- tions. Workers who have access to handheld computers enter into them the results of air tests and slump tests, while the truckâs RFID unit is used to link test data with the truck ID. RFID tags are then affixed to concrete test cylinders and associated with the delivery by truck ID and time of delivery. Once the delivery wraps up, the completion time is transmitted to the batch plant, so planning can begin for the next truck assignment. Upon the truck arriving at the batch plant, the scanner at the batch plant collects data on truck speed and route information. Meanwhile, the RFID tags placed on concrete cylinders are essential for coordinating the lab testing process. Test results can then be used to streamline invoicing and payments to the concrete supplier, contractor, and testing lab. Beginning in the mid-1990s, Alberta Transportation sought to develop an automated system capable of tracking construction materials from their point of origin to the jobsite (Gavin, Lo, and Humphries, 2004). A 1993 pilot project partially automated the process by installing RFID tags on haul tucks. Load data were captured at weight scales and stored on a computer, while at the jobsite, road checkers (i.e., personnel responsible for verifying and recording load weights) used handheld portable readers to communicate with RFID tags. However, manual data entry and checks were still required, data capture at the scale proved inconsistent, and partial auto- mation did not reduce engineering staff costs. Following a 2000 feasibility study that surveyed other transportation agencies to understand their use of automated data collection on truck hauls, Alberta Transportation piloted a new project focused on automating materials tracking. The agency contracted with a private firm it had previously partnered with to devise and test an automated data collection system. The system design consisted of a computer enabled with satellite communications and equipment at the scale house, two handheld computers (one equipped with GPS, the other enabled with satellite communications), and an off-site server. When a truck entered a scale, the computer recorded its ID number, net load weight, material type, and time; the truck driver received a load receipt before exiting. These data were then transmitted to the server and a handheld computer stationed aboard the paver. In turn, this handheld device tied into the server and the road checkerâs handheld computer. The road checker could use their device to view a list of incoming trucks. Once a load arrived, the road checkerâs device recorded GPS coordinates of the delivery location; the system was also capable of generating tonnage spread rate calculations in a separate report. Load and unload data were transmitted to the home server at 10-minute intervals and GPS coordinates converted to highway kilometer values. While Alberta Transportation deemed the pilot successful, the reliability of handheld devices was inconsistent. Among the benefits noted with the system were that consul- tants gained access to real-time data, letting them monitor progress on construction activities remotely, improvements in safety, more accurate haul data (due to less manual data entry), and better monitoring and enforcement of overweight loads. A preliminary cost-benefit analysis also suggested investment in the automated monitoring system produced net financial benefits. Another early illustration of RFID and GPS technologies being used to track materials from the plant to jobsite is Peyret and Taskyâs Material Traceability System (Peyret and Tasky, 2003). For each batch of asphalt, the system automatically collects data related to fabrica- tion characteristics from a plantâs existing monitoring and quality control systems. Data are then downloaded into an RFID tag mounted on the haul truck. For the pilot study described,
16 Electronic Ticketing of Materials for Construction Management information on quality parameters sourced from the plantâs computers, the weighing station, and other miscellaneous data (e.g., type of mix design, coordinate information) were written to the RFID tag. Once a haul truck arrives on the construction site, batch information is automatically transferred to the paver information system; GPS locates where material is being laid on the roadway. Software developed for the pilot was capable of visualizing where different batches of asphalt were placed using graphical plots that traced the paver movements. When they proposed a tracking system using bar coding technologies in 2008, Lee and McCullouch (2008) could identify no transportation agencies that had in place automated materials tracking systems. Their proposed system relies on handheld computers and pen-based bar code scanners to produce material delivery records. Figure 2.4 illustrates the automated procedure for tracking materials delivery. Once a contractor places an order with a materials supplier, the supplier adds order information (e.g., quantities, delivery dates, number of deliveries) to their database. Delivery tickets with corresponding bar codes are printed for each delivery. Drivers receive a ticket once material is loaded into their vehicle. When they arrive on a construction site, drivers present the bar-coded ticket to an inspector, who is responsible for collecting all tickets and scanning them into a computer. Records maintained by the contractor, supplier, and owner are updated through this process. Suppliers can then create an invoice, expediting the payment process. Because physical tickets would still be printed, the system is not paperless and only partially automates tracking. Nonetheless, prototypes of bar-coded tickets were field- tested on an INDOT project, with agency staff expressing interest in expanding the systemâs use. It thus provides an interesting example of incorporating bar codes into materials tracking. Figure 2.4. Proposed materials tracking system from Lee and McCullouch (2008).
Literature Review 17 Blending field research and conceptual model building, Nasir et al. (2010) put forward an implementation framework for automated materials tracking. Fieldwork took place in the context of two construction projects where materials were trackedâone a combined cycle generat- ing plant and the other a coal-fired power plant. Onsite, RFID tags were affixed to construction components while data collectors bearing mobile reader kits consisting of a GPS unit, RFID reader, and handheld computer walked through the material storage facility. As the data collectors moved around, the GPS receiver recorded their location while the RFID reader documented which tagged items were near them. Maps indicating the locations of tagged materials were distributed to workers so they could quickly identify tagged components. At one pilot study site, the amount of time required to locate an item with the automated tracking system fell from approximately 36 minutes before adoption to just under 5 minutes after. Supervisors noted using the system increased labor productivity and reduced the number of materials classified as temporarily lost because they could not be located quickly. Building on the success of this field trial, Nasir et al. (2010) proposed an implementation model for automated materials tracking, the purpose of which is to help stakeholders determine whether a project is a viable candidate for adoption of automated materials tracking. They specify conditions under which it is appropriate to use an automated system and methods and strategies for evaluating dif- ferent tracking systems, performing a cost-benefit analysis, and installing and deploying a tracking system. While their model is geared more toward identifying and tracking discrete elements, several of the field deployment options discussedâsuch as the use of gates or portal structures at construction sites, warehouses, and suppliersâare salient in a transportation context and suitable for working with bulk materials. Arguing that previous RFID-based methods of tracking materials were inadequate, Kasim (2015) described a prototype systemâIntegrated Materials Tracking Systemâthat synchronizes materials tracking and resource modeling (equipment). The integrated system leverages commercially available project management software and encompasses the registration of materials in a database system, materials tracking, and automated identification of materials during installation; the latter functions are integrated with resource modeling. System users are grouped into two categories: manufacturers and contractors. Manufacturers can register construction materials associated with particular RFID tags, while contractors have the ability to view the status of materials and RFID tag information. When trucks are loaded with material, the date, time, product, location, and other information are written to RFID tags by a reader. Although conceptually similar to other systems described in this section, the integration of information into project management software and its use in resource modeling calls to attention the importance of developing a holistic approach to materials tracking and using knowledge generated through this process to strengthen project management. Several researchers have proposed systems that measure the quantity and track the movement of bulk materials on construction sites. Shehab (2009) presented a system that automates the measurement of conical stockpiles. The systemâs design is intended to minimize human involve- ment in monitoring activities, support heightened surveillance of earthmoving operations, and give workers and managers rapid access to valuable information that can be used to inform corrective actions. Relying on a combination of automated distance measurement technologies, image analysis, and artificial intelligence, the system has three modules: (1) data acquisition, (2) data transfer, and (3) data analyses. The data acquisition module leverages a wireless digital camera and RFID real-time location services (RFID-RTLS). As materials are added to or removed from a stockpile, the camera snaps picturesâwhich capture the changing shape and volume of a stockpileâwhile the RFID-RTLS system measures a stockpileâs distance from the camera. Data are then transferred to a field host server. The data analysis module encompasses image enhancement, which isolates stockpiles, eliminates noisiness, and measures associated attributes (e.g., area, major and minor axis length), and a neural network system. The neural network processes
18 Electronic Ticketing of Materials for Construction Management the measured parameters and distinguishes stockpiles from background objects. Stockpile vol- umes are calculated by converting 2-D features into volumes reported in cubic yards or meters. On its own, a system like this would not be sufficient for materials tracking, but it highlights an innovative approach to inventorying materials that could be incorporated into a tracking system (see also Table 3.4 and the final paragraph of this section). Though not focused explicitly on materials tracking, Hubbard et al.âs (2015) investigation of pairing off-the-shelf RFID systems and UAVs is informative, as this combination of technologies could plausibly be leveraged to measure and monitor bulk material quantities. As part of the proof-of-concept study, RFID readers were installed on a UAV and three RFID tags with initial read ranges of over 1 m on the floor of an indoor facility. Three test flights were conducted, with an overall success rate of 56%. Manually controlling the UAV made it challenging to maintain consistent speed and height, while the RFIDâs weight (attributable to the payload) reduced flight time. Possible use cases for UAVâRFID pairings include identifying material on jobsites, inte- grating them with building information models to generate 3-D representations of components with an RFID tag, and facilitating project control and management. Taiwan has established a system for tracking the disposal of surplus soil generated on project sites that relies heavily on manual inputs. The system is cumbersome because it requires signifi- cant labor for reporting data, and errors creep into reporting, because of both unintentional and intentional actions. Seeking to circumvent problems with this system, Huang and others (Huang and Tsai, 2011; Huang, Tsai, and Wang, 2019) designed and piloted an RFID-based tracking system that shares many commonalities with others described in this section. Fully auto- mated, it takes advantage of RFID technologies, cameras, and real-time data transfer so regula- tors and stakeholders can remain knowledgeable of disposal activities. Before moving any soil, a contractor submits a project application that contains information about haul vehicles, disposal sites, and the amount and types of soil that will be moved. Upon approval, the contractor receives RFID tags, which they apply to a truckâs windshield. At the construction site, RFID equipment and a computer system are installed. As a truck enters the site, the RFID reader notes the time, and cameras take photos of the vehicle. Upon exiting the facility, the RFID reader again records the time, and cameras acquire more imagery. A similar process is used to document truck and load information at disposal sites. Once all of the soil has been unloaded, a control server determines the amount of surplus soil the project has produced in real time and generates a report. Despite the fact that the system generally performed well, equipment was prone to overheating, unstable internet connections at times created problems related to data transfer and processing, and the performance of RFID tags was degraded by interference from metal surfaces and moisture (however, there are RFID tagging solutions that minimize the problem of metal interference). Several commercial vendors offer products that facilitate the automation of materials tracking. Their platforms have affinities with the conceptual, experimental, and piloted systems described above. Stockpile Reports has developed an inventory system that takes imagery generated from a smartphone or UAV and calculates stockpile volume and condition; it can be used to facilitate holistic management of stockpiles. Another player in the materials tracking space is Earthwave Technologies, which the Iowa DOT partnered with on its e-ticketing initiative. Full details of this case example can be found in Chapter 4. The companyâs approach involves its software processing data from GPS transponders located onboard vehicles. GPS transponders record time-stamped data on when a vehicle moves across geofences and into or out of designated areas (e.g., plant, scale, project site, paver). Inspectors located onsite equipped with tablet computers can thus monitor the location of trucks as they travel from the plant, which enables better monitoring of delivery timing and quality control (Iowa Department of Transportation, 2016).
Literature Review 19 2.4 Conclusion There is clear momentum behind e-Construction. With its selection as an innovation for EDC-3 and EDC-4 and with a growing number of transportation agency and construction industry stakeholders working aggressively to integrate sophisticated technologies into their operations and embrace a paperless project environment, it is likely the pace at which e-Construction technologies are implemented will continue to accelerate. As documented in this review, the conceptual foundations of the current systems used to automate materials tracking date to the 1990s; however, only with recent advances in RFID, GPS, e-ticketing, and other realms has it become possible to build and deploy these systems on a wide scale. Many contemporary systems used to track materials do not differ significantly in their architecture from those imagined over 20 years ago. Bulk materials pose a unique tracking challenge because unlike discrete elements they cannot be directly tagged with an RFID device or GPS unit. Although it is unclear whether emergent technologies such as UAVs and advanced remote sensing will make it easier to track bulk materials per se, transportation industry stakeholders have benefited from the emerging crop of systems, which rely on tracking vehicles carrying asphalt, aggregate, concrete, millings, and other materials and using e-ticketing and software apps to more efficiently perform monitoring, control inventory, and generate invoices.
