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    <title>Transport Research International Documentation (TRID)</title>
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    <language>en-us</language>
    <copyright>Copyright © 2026. 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>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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      <title>Aviation laser strikes in Canada, 2022–2024: temporal trends, risk factors, and security implications</title>
      <link>https://trid.trb.org/View/2683181</link>
      <description><![CDATA[Laser strikes pose escalating risks to aviation security and safety. Using 1,275 reports from Transport Canada’s Civil Aviation Daily Occurrence Reporting System (2022–2024), this study analyzes temporal, geographic, and operational patterns. Incidents are concentrated in Ontario, Quebec, British Columbia, and Alberta, occur predominantly at night, and peak during approach and landing. A Poisson regression reveals a significant upward trajectory of approximately 1.5% per month, alongside strong seasonal variation, with August–October highest. Findings indicate the persistence of laser misuse and emphasize the need for targeted enforcement, awareness campaigns, and continued monitoring in Canadian airspace.]]></description>
      <pubDate>Wed, 24 Jun 2026 11:29:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2683181</guid>
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    <item>
      <title>Further Application of Pitch Independent Laser Doppler Velocimeter in Land Vehicle Autonomous Navigation</title>
      <link>https://trid.trb.org/View/2651921</link>
      <description><![CDATA[The strapdown inertial navigation system (SINS) and pitch-independent laser Doppler velocimeter (PI-LDV) integration represents a traditional navigation architecture. However, its effectiveness in obtaining precise altitude measurements remains constrained by the PI-LDV's inherent limitation of providing only one-dimensional velocity information. This study addresses this limitation by using the optical path structure of the PI-LDV to construct a frame capable of providing two-dimensional velocity information. To achieve this objective, two innovative integration methods are proposed: a SINS/PI-LDV loosely coupled integration method and a SINS/PI-LDV tightly coupled integration method, both of which consider the influence of potential laser beam fluctuations. Furthermore, a displacement increment measurement model is developed for the SINS/PI-LDV integrated navigation system to maximize the utilization efficiency of PI-LDV measurements while reducing the impact of sensor noise and outliers. The effectiveness of the proposed methods is rigorously validated through a comprehensive series of experimental tests, including: 1) extended-duration, long-distance tests using high-precision inertial measurement units (IMUs); 2) short-duration, limited-range evaluations using high-precision IMUs; and 3) two additional long-distance verification experiments using both high-precision and medium-precision IMUs. Experimental results demonstrate that the proposed method significantly outperforms traditional methods, particularly in height accuracy. Notably, the performance advantages become more pronounced when implementing the SINS/PI-LDV integrated navigation system with medium-precision IMUs, suggesting enhanced practical applicability in cost-sensitive applications.]]></description>
      <pubDate>Mon, 26 Jan 2026 08:41:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2651921</guid>
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    <item>
      <title>Investigating the LiDAR Beam Count Needed for Effective Vulnerable Road User Detection</title>
      <link>https://trid.trb.org/View/2592907</link>
      <description><![CDATA[Multi-array LiDAR Sensors have been widely used for Vulnerable Road Users (VRU) understanding. With recent advancement in LiDAR technology its resolution has been improved significantly, from 16 beams to 128 beams, though this has also led to a proportional increase in cost that may limit scalability in real-world deployments. This raises an important question: What is the minimum number of beams required for LiDAR to accurately detect VRUs? Is more always better? In addition, how robust is LiDAR-based VRU detection when some LiDAR beams are missing due to certain weather conditions such as heavy rain, snow, or fog? This study investigates the robustness of VRU detection performance against LiDARs with different beam numbers. The authors evaluate the widely used PointPillars Deep neural network architecture under varying LiDAR beam configurations using KITTI dataset. The findings reveal that car detection remains robust with only a 0.1% drop in average precision (AP) even when LiDAR beams are reduced by 50%. In contrast, cyclist detection experiences the the most significant degradation (9.4% AP drop), while pedestrian detection shows moderate resilience with a 1% AP decrease but an 8.8% decline in orientation accuracy. This differential impact across road user types indicates that 32-beam LiDAR systems offer sufficient accuracy for vehicle detection, while higher beam counts remain beneficial for reliable VRU monitoring in traffic safety applications.]]></description>
      <pubDate>Thu, 09 Oct 2025 11:36:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2592907</guid>
    </item>
    <item>
      <title>On the performance of a UAV-based Malaga-distributed FSO/FSO communication system with NOMA</title>
      <link>https://trid.trb.org/View/2549328</link>
      <description><![CDATA[Non-Orthogonal Multiple Access (NOMA) is an efficient communication technique that can offer improved spectral efficiency, ultra-low latency and massive connectivity and its integration with Free Space Optical (FSO) communication can improve the network capacity to a great extent. In this manuscript, an Unmanned Aerial Vehicle (UAV) is employed as a relay in an FSO/FSO downlink network, comprising of two users, user 1, U1 and user 2, U2, using Amplify-and-Forward (AF) protocol. UAVs can prove to be assets in disaster-struck situations (during natural disasters such as earthquakes, floods, etc.), when all terrestrial communication is at halt. The performance of this system is determined in the presence of atmospheric attenuation, Malaga (ℳ) turbulence fading, pointing errors and Angle-of-Arrival (AoA) fluctuations. Heterodyne detection (HD) technique is used for information detection at the users for providing improved sensitivity and Signal-to-Noise Ratio (SNR). The closed-form expressions for Outage Probability (OP), Ergodic Capacity and Bit Error Rate (BER) are derived in terms of Meijer-G function and OP is analyzed with respect to different weather conditions, turbulence levels, pointing error coefficients, NOMA coefficients and Field-of-View (FoV) angles. It is observed that at an SNR of 0 dB, the outage at U1 and U2 is 0.5489 and 0.7423, respectively. A comparison of OP is presented for the cases of HD and Intensity Modulation/Direct Detection (IM/DD) techniques and for NOMA and Orthogonal Multiple Access (OMA) technologies. Ergodic Capacity is analyzed for different turbulence strengths and pointing error values and it can be noticed that it is enhanced by reducing the turbulence strength and pointing error impairment. BER is observed for different modulation schemes and it is found to be 7.7×10−3, 1.9×10−2, 7.9×10−2 and 2.8×10−2, for QPSK, 8-PSK, 16-PSK and 16-QAM, respectively, at an SNR of 30 dB. In addition, BER is analyzed for clear, rainy and foggy weather along with different pointing errors and turbulence regimes. Monte-Carlo simulations are also carried out in order to validate the correctness of the obtained analytical results.]]></description>
      <pubDate>Thu, 29 May 2025 09:22:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2549328</guid>
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    <item>
      <title>Aerial Base Stations for Global Connectivity: Is It a Feasible and Reliable Solution?</title>
      <link>https://trid.trb.org/View/2319190</link>
      <description><![CDATA[Even though achieving global connectivity represents one of the main goals of 5G and beyond wireless networks, exurban areas are still suffering frequent outages because of the lack of proper telecom infrastructures, which are often available only in urban areas. Indeed, cellular network design is usually capacity driven, and thus the densities of base stations (BSs) follow mostly population and especially revenue densities. Contextually, the authors focus on one of the most promising solutions to provide sufficient and reliable coverage in far-flung areas: aerial base stations (ABSs), which consist of unmanned aerial vehicles (UAVs) carrying cellular BS equipment. In this article, the authors extensively discuss the problem of bridging what is called the urban–rural digital divide (i.e., the connectivity gap between urban and rural areas) from various perspectives. First, the authors showcase various alternative solutions and compare conventional terrestrial networks with aerial networks from a techno-economic point of view. Then, the authors highlight the topological aspects of rural environments and explain how they can affect the actual design of cellular networks. In addition, the authors investigate both the coverage probability and the reliability of the communication links via simulations, proving that the integration of ABSs can be quite promising in a 6G perspective. Finally, the authors propose two original extensions of their case study as open problems.]]></description>
      <pubDate>Fri, 26 Jan 2024 10:02:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2319190</guid>
    </item>
    <item>
      <title>Maximizing wireless power transmission for electric vehicles with high-intensity laser power beaming and optical orthogonal frequency division multiplexing</title>
      <link>https://trid.trb.org/View/2296390</link>
      <description><![CDATA[This paper presents a method for determining the optimal power transmission path for wirelessly charging electric vehicles using high-intensity laser power beaming in environments with multiple power transmitters and receivers. The proposed method uses an optical orthogonal frequency division multiplexing system. The power receiver selects the optimal power transmitter and wireless power channel based on the maximum power requirement. The paper also validates the proposed method through simulation and experimentation.]]></description>
      <pubDate>Sun, 24 Dec 2023 16:52:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2296390</guid>
    </item>
    <item>
      <title>Research on Laser Beam Welding of Nickel</title>
      <link>https://trid.trb.org/View/1973479</link>
      <description><![CDATA[A study of weld joints of nonferrous, Nickel 201 alloy sheets using a new generation disk laser as the green welding technology for effective manufacturing was carried out, and the results are presented in this paper. Weld joints of the Nickel 201 sheets 2.0 mm thick were welded by laser without an additional material at a flat position, using high purity argon as the shielding gas. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The influence of welding speed and laser power to the joint quality was investigated. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.]]></description>
      <pubDate>Mon, 11 Sep 2023 11:39:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1973479</guid>
    </item>
    <item>
      <title>Laser exposure incidents and aviation safety in the United States: should we be concerned?</title>
      <link>https://trid.trb.org/View/2205308</link>
      <description><![CDATA[Laser pointers directed at commercial aircraft by individuals in the vicinity of airports and flight routes are a growing threat to the safety of air travel. During a critical phase of flight, such as landing or takeoff, a laser strike can cause significant distraction or visual impairment to the pilot. This paper investigates laser-related incidents and injury in the United States over the last decade. Using daily data on laser exposure reported by pilots and crew members, and controlling for laser color, hour of the day, day of the week, among other controls, we find that the likelihood of suffering a laser-induced injury is inversely proportional to altitude, but positively related to laser incident frequency.]]></description>
      <pubDate>Mon, 28 Aug 2023 09:34:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2205308</guid>
    </item>
    <item>
      <title>Human Factors Evaluation of Commercial Aviation, Low Intensity, Iteration 2 (CALI-2) Laser Eye Protection</title>
      <link>https://trid.trb.org/View/2196866</link>
      <description><![CDATA[Laser strikes are an ever-increasing concern in the civil aviation community and are of particular concern to the Federal Aviation Administration (FAA). They pose a direct threat to aviation safety and air traffic coordination, particularly when they occur during critical phases of flight such as takeoff and landing. Laser strikes cause a variety of negative physiological and psychological effects, including glare, flash blindness, afterimages, and startle (Nakagawara et al., 2003, 2004). Laser eye protection (LEP) spectacles are designed to mitigate these effects by attenuating the visible and infrared light emitted by handheld lasers. While LEP spectacles are effective in mitigating the impacts of laser strikes on pilots, the attenuating properties of the lenses cause a shift in color perception. As such, wearing the LEP spectacles may impact pilots’ ability to use color-coded information during flight. The purpose of this study was to determine whether using the Air Force Research Laboratory’s (AFRL) Commercial Aviation, Low Intensity, Iteration 2 (CALI-2) LEP spectacles impacts flight performance and normal pilot duties during airborne phases of flight in a general aviation aircraft. Fourteen Instrument-Rated pilots volunteered to complete a series of simulated flights with the CALI-2 LEP spectacles in a variety of simulated flight environments. Overall, the findings suggest that pilots should be able to wear CALI-2 LEP spectacles in real aircraft without affecting their ability to carry out normal pilot duties. Results indicate that pilot participants’ ability to follow navigational and flight guidance information and ability to perceive and comprehend color-coded alphanumeric information is preserved when using the CALI-2 LEP spectacles. Questionnaire and interview responses from pilot participants revealed that the LEP spectacles were compatible with displays, controls, and instruments inside the aircraft, and do not substantially hinder visibility of environmental features such as airfield lighting. Implications for these findings in terms of LEP use during real-world flight are discussed, along with future directions for LEP research and implementation in the U.S. National Airspace System (NAS).]]></description>
      <pubDate>Tue, 20 Jun 2023 10:05:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2196866</guid>
    </item>
    <item>
      <title>Finite element investigation of residual stresses during laser powder deposition process as an innovative technique to repair worn rails</title>
      <link>https://trid.trb.org/View/2087736</link>
      <description><![CDATA[In recent years, a great deal of effort has been made to use laser powder deposition (LPD) as a novel way of repairing damaged metal components. Minimizing the residual stress in the LPD process to prevent premature failure and delamination is very important, so the proper deposition material and technique must be used. This paper studies the use of the LPD process to repair a standard U.S. light rail by building up multiple deposition layers onto the worn railhead. The investigation of the rail repair process was performed through the systematic finite element modeling of the multi-layer LPD process using the element birth-and-kill technique. In this technique, the effects of the type of deposition material and the preheating temperature on the magnitude and distribution of the residual stresses were studied. The candidate deposition steels included 304L stainless steel, 410L stainless steel, Stellite 6, and Stellite 21, each one of which was explored separately. To analyze the effect of preheating, various temperatures, that is, 25°C, 400°C, 600°C, 800°C, and 900°C, were set as the initial temperatures of the railhead. Ultimately, it was shown that preheating has a significant effect in minimizing the residual stresses. It was found that each increase in the preheating temperature resulted in an overall decrease of the residual stresses by 25%–30%. In addition, Stellite 21 was identified as the most promising deposition steel in terms of giving the least risk of failure and delamination.]]></description>
      <pubDate>Tue, 07 Feb 2023 09:16:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2087736</guid>
    </item>
    <item>
      <title>A clustering-based simplification of massive automobile-bodies point cloud for lightweight design</title>
      <link>https://trid.trb.org/View/2065590</link>
      <description><![CDATA[Adaptive simplification for massive and large-scale automobile-bodies point cloud obtained by 3D laser-scanning has been proven to be an effective technology to conduct lightweight design. This paper introduces a point-based algorithm to simplify laser-scanning point cloud without any support of fitted surface. The intrinsic characteristic of laser-scanning data is investigated to produce a topological connectivity for adjacent points in scanlines. The authors explore an automatic normal-vector estimation framework through the relationship between normal-vector and its adjacent geometric elements. To retain more points in high-curvature areas and fewer points in planar regions efficiently, the local normal-vector variance is adopted to determine subdivision-decision condition. The boundary points are detected and then preserved before non-uniform subdivision. A relevant simplification system based on the authors' algorithm is developed. Many simplification cases are implemented to validate the effectiveness of the authors' method and demonstrate the feasibility for automobile-bodies point cloud. The comparison with other point-based methods is also performed to illustrate the superiority of the authors' method.]]></description>
      <pubDate>Tue, 13 Dec 2022 10:04:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2065590</guid>
    </item>
    <item>
      <title>Numerical Simulation of Laser Welding Process for Aluminum</title>
      <link>https://trid.trb.org/View/1899823</link>
      <description><![CDATA[In the development of can-sealing, the aluminum welding is usually employed. However, it often causes trial and errors in the actual test. To prevent the errors, many simulation models were developed, but the accuracy was not enough. This paper presents the new methodology using model parameters. First, the authors identified the absorption ratio of fiber laser for solid and liquid aluminum by combining measured temperature with heat transfer simulation. Second, they optimized parameters for Fresnel absorption and recoil pressure model using response surface methodology. Finally, the authors demonstrated that the simulation result matches well with the actual test.]]></description>
      <pubDate>Thu, 20 Jan 2022 12:15:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1899823</guid>
    </item>
    <item>
      <title>Improvement of the adhesive bonding properties of an polyamide 6 injection molded fiber reinforced plastic component by laser beam pre-treatment</title>
      <link>https://trid.trb.org/View/1880526</link>
      <description><![CDATA[Fiber-reinforced plastics (FRP) are widely used in the automotive industry due to their lightweight construction potential. Especially, injection-molded components are very popular because of their short cycle times. Unfortunately, this manufacturing process results in some disadvantages for delayed adhesive bonding. On the one hand, such thermoplastics have a very low surface energy (Polyamide 6 (PA6) 36 mJ/m), on the other hand residues of release agents on the surface hinder adhesion between product and adhesive. These disadvantages have to be overcome by the right surface pre-treatment process. Currently, a solvent-containing process is usually used for this purpose. If necessary, the use of primer is common. In the presented paper, the pre-treatment process of an injection-molded component made of polyamide 6 reinforced with glass short-fibers is presented. First, material-specific properties are measured. The influence of laser pre-treatment at 355 nm and 1064 nm wavelength is investigated. Measurements of surface free energy and surface roughness are conducted. The bonding strength is validated by peel test and tensile shear tests. The shear strength was doubled by laser pre-treatment at a medium energy level, partially cohesive failure of the adhesive was achieved. Both investigated wavelengths led to a great improvement of bonding strength at suitable parameters.]]></description>
      <pubDate>Mon, 25 Oct 2021 09:16:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1880526</guid>
    </item>
    <item>
      <title>A new flexible laser beam profiler for the inspection of train wheels</title>
      <link>https://trid.trb.org/View/1845838</link>
      <description><![CDATA[In this paper, a flexible laser beam profiler is proposed to easily measure the profile of a train wheel for railway inspection. It only requires two laser beams (together and in parallel) to obtain two three-dimensional point-clouds based on the laser triangulation principle. Either the laser beam profiler or the wheel can be freely moved. The motion need not be known. The wheel profile will be obtained in two steps. First, the wheel axis position and orientation are obtained by minimizing the distance between one of the point-clouds and the other translated point-cloud, and translation is defined as a rotation of any point on the point-cloud around the wheel axis until it lies on the other point-cloud's laser plane. In the second step, the wheel profile is extracted by selecting one of the point-clouds and rotating it about the wheel axis and by finding the intersection of rotating points and a perpendicular plane, the perpendicular plane is defined as any arbitrary plane which passes through the wheel axis. This method is useful particularly for obtaining geometrical parameters of a wheel such as flange height, flange slope and flange thickness. In order to commission the proposed method, a prototype system was designed and manufactured. The performance of the system, evaluated in different circumstances, shows a measurement error of up to 2%. Compared with classical methods utilizing a caliper or those which use expensive equipment or additional parts such as reference guides, the proposed method is easy to use and flexible. Also, a novel calibration method is utilized to calibrate the system accurately and freely.]]></description>
      <pubDate>Wed, 09 Jun 2021 15:33:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1845838</guid>
    </item>
    <item>
      <title>Coarse-to-Fine Segmentation on LiDAR Point Clouds in Spherical Coordinate and Beyond</title>
      <link>https://trid.trb.org/View/1766971</link>
      <description><![CDATA[Active sensors such as LiDARs (light detection and ranging) are popular in autonomous driving systems for perception and localization. Existing perception approaches process the rich 3D LiDAR point clouds for object detection, tracking and recognition. These methods generally require an initial segmentation procedure containing two steps: (1) filter points as ground and non-ground points, and (2) cluster the non-ground points into objects. Leveraging a range image created in Spherical coordinates, this paper proposes a field-tested coarse-to-fine 3D point cloud segmentation framework to achieve both speed and accuracy. Under this framework, a basic version and an advanced version of segmentation algorithms are presented. In the basic version, the authors demonstrate how a coarse-to-fine scheme is applied in a range image for ground filtering and object clustering. In the advanced version, the authors move forward to reduce the processing time and correct the motion distortion by directly dealing with the data packets instead of the range image. Tests in the well-known KITTI dataset and field experiments in public roads have shown that the method significantly improves the speed of 3D point cloud segmentation whilst maintains good accuracy.]]></description>
      <pubDate>Tue, 25 May 2021 16:22:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1766971</guid>
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