<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ADcmm%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>TRB Conference on Advancing Additive Manufacturing and Construction in Transportation, November 7–8, 2024, Irvine, CA</title><link>http://pubsindex.trb.org/view/2600911</link><description><![CDATA[The Transportation Research Board (TRB) Conference on Advancing Additive Manufacturing and Construction in Transportation was held November 7–8, 2024, at the Arnold and Mabel Beckman Center in Irvine, California. The Additive Manufacturing (AM) process and Additive Construction (AC) applications are linked by 3D printing technical concepts. This global forum identified future transportation research needs by providing an idea of what is possible based on how the technology is being used now. Conference participants left with a better understanding of how increased use of AM can affect logistics, supply chains, movement of goods, and related fields, and explored research into AC that is used in large-scale mobile AM (i.e., gantries, extruded structures, forms, molds and systems). This conference summary, prepared by Victoria Deguzman, is a compilation of the presentations and a factual summary of the ensuing discussions at the event. Session topics included:  (1) National Science Foundation and civil, mechanical, and manufacturing innovation program in AM and transportation; (2) concrete materials in AM and AC; (3) robotics, automation, and AC; (4) steel construction in AM; (5) standards and policies; (6) freight and supply chain; (7) culverts, pipes, and other structures; (8) constructing with in situ materials; and (9) geopolymers and other cementitious composites.]]></description><pubDate>Thu, 18 Sep 2025 09:51:01 GMT</pubDate><guid>http://pubsindex.trb.org/view/2600911</guid></item><item><title>Integrated Scheduling of Automatic Guided Vehicles and Automatic Stacking Cranes in Automated Container Terminals Considering Landside Buffer Zone</title><link>http://pubsindex.trb.org/view/2204604</link><description><![CDATA[The enhancement of the efficiency of automated container terminals (ACTs) and promotion of energy saving and emission reduction have attracted increasing attention in the construction of resource-saving and environment-friendly ports. In this paper, an integrated scheduling optimization model of automatic guided vehicles (AGVs) and automatic stacking cranes (ASCs) is proposed to resolve the problem of long round trips and high energy consumption of ASCs in typical ACTs. The configurations of ACTs considering the landside buffer zone were analyzed. First, the feasibility of integrated scheduling when considering a landside buffer zone is introduced. The study also analyzes the problems that must be resolved for the integrated scheduling of AGVs and ASCs using the aforementioned layout handling technology. Subsequently, a multi-objective optimization model for the integrated scheduling of AGVs and ASCs considering the landside buffer zone was developed. In this model, the operations of AGVs and ASCs are divided into four categories: load transport, no-load transport, load/unload, and waiting. The objective of formulating the model was to minimize the makespan and total energy consumption. Finally, an improved non-dominated ranking genetic algorithm, NSGA-II, is employed to optimize the model. The results show that the makespan and total energy consumption of the integrated scheduling of AGVs and ASCs considering the landside and seaside buffer zones are better than those considering only the seaside buffer zone.]]></description><pubDate>Sat, 01 Jul 2023 17:08:16 GMT</pubDate><guid>http://pubsindex.trb.org/view/2204604</guid></item><item><title>Smart Installation and Monitoring System for Large Anchor Bolts of Support Structures Made with 3D Printing Enhancement</title><link>http://pubsindex.trb.org/view/2110235</link><description><![CDATA[Anchor bolts, as a connection system used at the base of most highway support structures, commonly suffer from loosening effects that may impose high risk on collapse of these support structures. The current inspection method on loose anchor bolts only stops at the manual level. By punching the washers beneath the nuts with hammers, if the washer moves, then the bolts are considered loose. However, for each inspection team, there may be hundreds, or even thousands of structures using anchor bolts, so with an average of more than 8 anchor bolts implemented at the base of each structure, the inspection work can be extremely time-consuming. Furthermore, when the washer moves under punching, the tension inside anchor bolts can be as low as less than 20% from the required value. In this case, the support structure can already have anchor bolts that have lost most of pretension from installation. Thus, the stability of the supporting structures can be at great risk before inspection. This project aimed to develop a capacitance-based smart washer system to serve as an efficient way to monitor the tension inside the anchor bolts before the loose anchor bolts could cause severe stability issues. After several design trial and errors, the final prototype of the smart washer system consists of  the following components: a top direct tension indicator (DTI) washer, a middle smaller sized spacing washer, a bottom plain washer and a rubber ring as dielectric material, a couple of copper rings attached to top and bottom washers, and 3D printed polylactic acid (PLA) attachments as insulation layer. From the results and observations of two stages of the project, the concept and prototype of the smart washer system have been proven efficient, and the sensor system was able to detect change of tension inside the anchor bolts. With the proper modification for outdoor use to eliminate the environmental interruptions of the data transmission system, this smart washer system can be a potential candidate for the inspection method on the anchor bolts.]]></description><pubDate>Tue, 07 Feb 2023 18:34:29 GMT</pubDate><guid>http://pubsindex.trb.org/view/2110235</guid></item><item><title>Influence of External Vibration on the Gravitational Flow Characteristics of Cementitious Materials: A Perspective from Application in Additive Manufacturing</title><link>http://pubsindex.trb.org/view/1925990</link><description><![CDATA[Three-dimensional (3D) printable concretes require high plastic yield stress to retain the shape of the printed layers, however, to enhance the ease of pumping the cementitious system should have as low a plastic yield stress as possible. To address these opposing needs for printing and pumping, a vibration-based active rheology-controlled system which temporarily reduces the plastic yield stress during pumping has been designed. To study the response of the rheological properties of the cementitious system and its response to vibrations, a test setup which can simulate the vibration that occurs during pumping has been developed. An EN445 flow cone was modified by mounting a frequency-controlled vibration setup. The effect of vibration on the flow initiation, flow topology, and flow rate of cementitious systems with three different water-to-binder ratios, two pozzolans (silica fume and metakaolin), and multiple dosage levels of high-range water reducer and viscosity modifying agents was studied. Results from this study suggest a strong correlation between plastic yield stress, and the frequency and amplitude of vibration with implications for 3D printing.]]></description><pubDate>Mon, 14 Mar 2022 16:24:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/1925990</guid></item><item><title>Effect of Geometry and Infill on Strength of 3D Printed Planar Matrices for Matting Applications</title><link>http://pubsindex.trb.org/view/1876598</link><description><![CDATA[3D (three-dimensional) printing was used as a rapid prototyping tool to determine the influence of cell geometry and infill materials on the physical properties of geometrically patterned matrices while subjected to compressive stress. Matrices of comparable patterns but varied scales and densities were fabricated from acrylonitrile butadiene styrene (ABS) plastic using fused deposition modeling (FDM) 3D printing. The test results confirm that some matrices reinforced by infill with sand, gravel, and mixtures of the two show better compressive strength than conventional concrete, and may find application in matting for airfield damage repair. The cell matrix geometry that demonstrated maximum strength (comparable with conventional concrete) was a hexagonal geometry with a relative density to solid plastic of 0.32 infilled with a mixture of sand and gravel. Additional data suggests that at larger scales, maximum strength comparable with conventional concrete could be achieved with even lower relative density.]]></description><pubDate>Sun, 12 Sep 2021 17:20:31 GMT</pubDate><guid>http://pubsindex.trb.org/view/1876598</guid></item><item><title>Developing Mix Proportions for Class C Fly Ash-Based Alkali-Activated 3D-Printed Concrete Mixtures</title><link>http://pubsindex.trb.org/view/1759411</link><description><![CDATA[This study investigated the use of class C fly ash (FA) as a precursor for alkali-activated mortar (AAM) for 3D-printed concrete (3DPC). AAMs with different water-to-FA (W/FA), alkaline activator-to-FA (Alk/FA), and sodium silicate-to-sodium hydroxide (SS/SH) ratios were examined to develop mixtures that can be tailored for different structural applications of 3DPC. The fresh properties, including extrudability and buildability, were evaluated through the open time (OT) and immediate deformation tests, respectively. Different cycle times (CTs) were applied to achieve a strain limit state necessary to maintain the printed shape. The strength of AAMs in different directions at different CTs was examined. Scanning electron microscopy (SEM) was carried out on AAM specimens having different CTs for a better understanding of the bond area. OTs ranging from 2.5?min to 31?min and axial strains ranging from 0.17% to 11.2% were achieved depending on the proportions of the AAMs and CT, which offers flexibility in optimizing the speed of printing and strength of concrete for different projects. The 3DPC specimens displayed anisotropic behavior compared with full-height specimens, where the compressive strength of full-height specimens was higher by 0.2% to 18% and 0.9% to 28% than 3DPC specimens when tested parallel and normal to the printing directions, respectively. SEM images and line scan indicated an approximately even intensity of the element concentration at the interfacial zones of AAMs having short CTs, which explained the relatively high compressive strength of those specimens. For AAMs having long CTs, there was a significant change in the intensity of the element concentration at the interfacial bond zone, and voids were observed resulting in low compressive strength of those specimens.]]></description><pubDate>Thu, 04 Feb 2021 10:57:31 GMT</pubDate><guid>http://pubsindex.trb.org/view/1759411</guid></item><item><title>3D-Printing of Ultra-High-Performance Concrete for Robotic Bridge Construction</title><link>http://pubsindex.trb.org/view/1759266</link><description><![CDATA[Automation and robotics are integral parts of many industries but their potential for field implementation has not been significantly recognized by the construction industry. This is mainly attributed to conventional construction and design practices which undermine the benefits offered by these new technologies such as repetitions, precision, time savings, and increased safety. There is a need for advanced materials and 3D-printing systems which are capable of constructing structural elements with performance that emulates conventionally cast elements. This study presents a detailed framework and performance metrics for materials and 3D-printing systems for bridge applications. In addition, a study was carried out on ultra-high-performance concrete (UHPC) which showed sufficient extrudability and workability for 3D-printing applications. A 3D-printing system was developed for 3D-printing of continuous additive layers of UHPC with accelerated heat curing. Accelerated heat curing was used to enhance buildability, expedite the printing of the UHPC layers, and maximize the number of printed layers within the material open time. The effect of heat curing on material properties was also evaluated to obtain the optimal temperature to satisfy compressive strength requirements. This research effort aims to augment automated construction techniques and develop solutions to extend the applications of accelerated bridge construction.]]></description><pubDate>Thu, 04 Feb 2021 10:57:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/1759266</guid></item><item><title>Testing Procedures on Materials to Formulate the Ink for 3D Printing</title><link>http://pubsindex.trb.org/view/1692964</link><description><![CDATA[Three-dimensional (3D) printing has been used in various fields to tackle applications difficult for conventional manufacturing. To realize the full potential of this technology in the transportation sector, it is imperative to identify suitable tests and mixtures for printing “inks” made of mortar. In this study, several conventional and non-conventional tests on mortars and cement pastes were conducted. This work highlights the correlation between the results of slump test and the deformation test that indicates the comportment of the mixture under a stack of printed layers. Moreover, a strong connection between yield stress and mini-slump is observed, demonstrating a simplification of the testing procedure, and a link between the mortar and the cement paste is developed. In the printing ink design phase, this association enables the prediction of flowability. The yield stress and the final radius of the mini-slump tests were very well correlated for the admixture tested. The use of the mini-slump test simplifies the testing procedure and allows for quicker formulations of admixtures in the printing ink.]]></description><pubDate>Wed, 08 Apr 2020 08:54:12 GMT</pubDate><guid>http://pubsindex.trb.org/view/1692964</guid></item><item><title>Properties of 3D Printing Mortar with the Development of a 3D Construction Printing (3DCP) Delivery System</title><link>http://pubsindex.trb.org/view/1685095</link><description><![CDATA[Over the last few years, 3D construction printing (3DCP), also known as additive manufacturing (AM) or rapid prototyping (RP), has increased in popularity in the construction industry. This method, which integrates automation in the building process, provides advantages over conventional construction techniques. These advantages include reduced cost, increased time efficiency, and safer construction process. This paper provides information regarding test methods and the properties of a prototype cementitious material designed for 3DCP. The tests include the determination of fresh properties (i.e., flow, unit weight, viscosity, and set times) and mechanical properties (i.e., compressive, tensile, and shear strengths). The potential of the material is demonstrated by 3D printing a structure 100?cm (40?in.) long and 30?cm (12?in.) high. The potential application of a “cured-on-demand” technique in 3DCP is also demonstrated.]]></description><pubDate>Wed, 19 Feb 2020 14:09:42 GMT</pubDate><guid>http://pubsindex.trb.org/view/1685095</guid></item><item><title>Early-Age Performance of 3D Printed Carbon Nanofiber and Carbon Microfiber Cement Composites</title><link>http://pubsindex.trb.org/view/1681986</link><description><![CDATA[3D printed cement composites with and without carbon nanofiber (CNF) and microfiber (CF) reinforcement within the cement ink were evaluated at seven days and compared with their traditionally cast counterparts. A liquid lubrication layer at the extrusion nozzle was noted. The reinforcement type influenced the formation of the extruded filament, with underextrusion seen during 3D printing with the CNF cement ink while sudden discontinuation of extrusion was experienced during 3D printing with the CF cement ink. No noticeable interfacial region between printed filaments was observed in the 3D printed cement composites, with the exception of air cavities between printed filaments of the composite fabricated with the CNF cement ink. Lower compressive strengths were seen in the direction orthogonal to the print path for the 3D printed composites compared with the cast composites. The addition of CFs within the cement ink reduced this strength difference and led to strain softening in the post peak behavior.]]></description><pubDate>Wed, 05 Feb 2020 15:23:27 GMT</pubDate><guid>http://pubsindex.trb.org/view/1681986</guid></item><item><title>3-D Printing in Transportation: Already in Action</title><link>http://pubsindex.trb.org/view/1508933</link><description><![CDATA[The construction industry already has used 3-D printing technology for quite some time—only the name is new. Of the many synonyms for 3-D printing in construction, the most commonly used is “additive manufacturing,” which is derived from the aerospace, automobile, biomedical, energy, consumer goods, and other industries. Other synonyms include “layered manufacturing,” “free-form fabrication,” and “digital manufacturing”. Unlike in other industries, the construction of buildings, bridges, highways, airport runways, marine structures, and other facilities traditionally has involved an additive, or layered, manufacturing process—one that traditionally has been manual and labor-intensive. Because construction and manufacturing have operated as separate industries, however, the existence of additive processes in construction has not been widely recognized by other industries. In this article, the author outlines the history of 3-D printing in construction from slip-form construction, shotcreting, and contour crafting to freeform construction or concrete printing. The present status of 3-D printing is discussed along with challenges facing 3-D printing applications including lack of coordination; size of construction printers; ink formulation/concrete mixture optimization; and incorporating reinforcing steel into 3-D printed structures.]]></description><pubDate>Tue, 24 Apr 2018 13:51:20 GMT</pubDate><guid>http://pubsindex.trb.org/view/1508933</guid></item><item><title>Characterization of Ballast Particle Movement at Mud Spot</title><link>http://pubsindex.trb.org/view/1496601</link><description><![CDATA[Mud pumping has been known to cause severe track degradation and compromise operation safety. It is normally a result of fast upward intrusion of wet subgrade soil through the voids in ballast and ballast particles being pushed downward to the soil simultaneously. Understanding of ballast particle movement characteristics at clean vs. muddy sites under dry vs. wet conditions are critical for railroad engineers to make timely and effective maintenance decisions. A recent field experiment was conducted to investigate particle movement under different ballast conditions using SmartRocks, a wireless device that can realistically sense, record and transmit wirelessly its movement in real-time. Three-dimensional (3D) printing technology is used to generate arbitrary shapes of SmartRocks that resemble realistic ballast particles. A control site with clean ballast and a site with known mud pumping problem were chosen from the NS’s Pittsburg division. These two sites were chosen from the same track in close proximity to make sure they experience the same traffic and weather conditions. SmartRocks were installed in different locations including both shoulders and cribs to investigate particle movement characteristics under both freight and passenger trains. The results show that the ballast particle movements are affected by many factors including ballast condition, wheel load, and train speed. In summary, ballast particles at the mud spot displayed significantly different movement patterns under both freight and passenger trains, which provides a knowledge base towards specific maintenance strategies for ballast with mud pumping problem.]]></description><pubDate>Thu, 22 Mar 2018 12:03:55 GMT</pubDate><guid>http://pubsindex.trb.org/view/1496601</guid></item><item><title>Transformational Technologies in Transportation: State of the Activities</title><link>http://pubsindex.trb.org/view/1407343</link><description><![CDATA[This report explores the status and applications of transportation goods, services, and systems that fall under the umbrella of transformational technology. Key transformational technologies include connected and automated vehicles, including shared use services; unmanned aerial systems (drones); Internet of Things (including smart cities); and cybersecurity. In addition, the following technologies that have potential to be transformational technologies include NextGen air transportation system, 3-D printing, and big data. The report explores the state of each technology development; the key players involved; methods used to demonstrate the technologies to a national audience; methods used to publicize the technologies and convene their proponents and stakeholders; the economic significance of technologies and associated business models; and the possibilities for wider impact through synergies with other key technologies or other adjacent matters.]]></description><pubDate>Fri, 13 May 2016 14:02:16 GMT</pubDate><guid>http://pubsindex.trb.org/view/1407343</guid></item><item><title>Local Sequence-Cut Method for AGV Dispatching Problem at Automated Container Terminals with Tandem Lift Quay Cranes</title><link>http://pubsindex.trb.org/view/1289838</link><description><![CDATA[The dispatching problem of automated guided vehicles (AGVs) between seaside quay cranes and landside yard cranes is a critical operation at container terminals.  This paper provides a mixed integer linear program for the problem with tandem lift quay cranes and proposes a new method, called Local Sequence-Cut (LSC), to solve the problem. As opposed to most conventional heuristics which pass a local solution during iteration, the LSC method is capable of reducing decision variable space very effectively through constructing local sub-problems and updating time bounds for container delivery to determine cut-off delivery sequences. Series of numerical experiments show the capability of the new LSC method to find near-optimal solutions in substantially reduced central processing unit (CPU) time compared to conventional commercial software.]]></description><pubDate>Fri, 28 Feb 2014 13:32:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/1289838</guid></item><item><title>Comparing Manned and Automated Horizontal Handling Equipment at Container Terminals: Productivity and Economic Analysis</title><link>http://pubsindex.trb.org/view/1289721</link><description><![CDATA[The choice to use horizontal handling transport in automated container terminals is not fully consistent in comparison with the automation of stacking cranes at the storage yard. Often the decision of whether to use an automated system between the berth and the yard area is not clear, and terminal operators tend not to use automated systems. The goal of this paper is to provide an economic analysis to determine under which conditions automated horizontal transport is more efficient than a semiautomated system. The study provided several simulation models to calculate the optimal equipment necessary to connect storage and berth subsystems in a maritime container terminal in fully automated and semiautomated scenarios. Data from the semiautomated container terminal at the Port of Barcelona, Spain, were used. In addition to the cost analysis, guidelines on the best alternative, considering labor costs, throughput movements per quay crane and year, and quay crane productivity are provided.]]></description><pubDate>Fri, 28 Feb 2014 13:32:29 GMT</pubDate><guid>http://pubsindex.trb.org/view/1289721</guid></item></channel></rss>