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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <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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      <title>Computational Fluid Dynamics Investigation of High Mast Illumination Poles: Influence of Light Fixtures</title>
      <link>https://trid.trb.org/View/2662989</link>
      <description><![CDATA[High Mast Illumination Poles (HMIPs) are lighting towers that are taller than 55 ft (16.8 m) and are typically located along highways and rest stops. In March 2019, a wind event, referred to as a “bomb cyclone,” caused several HMIPs in Kansas to excite and experience large-amplitude deflections on the order of several feet called “lock-in” behavior. Lock-in behavior is when the frequency of vibration matches a natural frequency of the structure and excess deformations will be observed. Pole vibrations can be caused by multiple wind actions and wind-structure interactions, including aeroelastic phenomenon like vortex shedding. Following the bomb cyclone event in 2019, the poles were inspected, and cracks were identified around the handhole openings in several of the structures. These poles were taken out of service having only been in service for approximately one year. Their premature failure caused significant concern. New, LED luminaires had been implemented with the construction of these poles. The Kansas Department of Transportation (KDOT) sought to learn if selection of LED luminaires (rather than older-style incandescent fixtures) had any influence on the behavior observed during this event. The goal of this research project was to examine and compare the behavior of wind flow past LED and incandescent luminaires used in Kansas using computational fluid dynamics (CFD) modeling. Two-dimensional models were developed in Abaqus/CFD 2016 representing a projection of the full lighting assembly at the top of an HMIP. Simulations were created for each luminaire type on assemblies including three and four fixtures. The angle of wind relative to the light fixture and wind speed were varied throughout the simulations. Three-fixture simulations used wind angles of attack of 0, 30, and 60 degrees and four-fixture simulations used wind angles of attack of 0, 22.5, and 45 degrees. All assemblies and wind angles of attack were simulated for wind speeds of 15 (6.7), 25 (11.2), 30 (13.4), 35 (15.6), and 45 mph (20.1 mps). Time histories of the resulting forces on the lighting assemblies in the along-wind and cross-wind directions were extracted from the models. Power spectral density (PSD) curves were developed, identifying the dominant frequencies in the time-history data. The peaks in the PSD curves were extracted and compared with the first three natural frequencies of four representative HMIP archetypes used in the state. Natural frequencies of those four HMIP archetypes were determined using structural models of the poles using Abaqus/CAE 2017. To account for uncertainties in the analyses, ±10% bounds around each natural frequency were used when comparing the peaks in the PSD data with structural natural frequencies. When a peak fell within these bounds, it was treated as a “hit,” having potential to excite that natural frequency mode and produce lock-in behavior. Hit counts were used to evaluate the data and compare each fixture type, angle of wind attack, and wind speed.]]></description>
      <pubDate>Thu, 05 Feb 2026 11:56:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2662989</guid>
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    <item>
      <title>Evaluation of Truck Traffic-Induced Light Pole Vibrations on the I-80 Le Claire Bridge</title>
      <link>https://trid.trb.org/View/2617972</link>
      <description><![CDATA[The results obtained from accelerometers mounted on the luminaires of the I-80 Le Claire Bridge over the Mississippi River near East Moline, IL, indicated peak acceleration forces of approximately 5 g. Due to hazards posed by luminaires falling onto traffic or the bridge deck, District 2 removed the lighting until a safe solution is tested and approved. It was found that the acceleration in the longitudinal direction of the bridge was found to be only about 2.0 g. The largest g forces were sustained at 45°, averaging 4.73 g +/- 0.17 g with an internal plastic pipe, and 4.82 g +/- 0.22 g with only a Fabreeka® vibration attenuation pad and washers bolted in between the pole base and parapet. Transverse accelerations, which are perpendicular to the long axis of the bridge, were only slightly less at 3.99 g +/- 0.45 g with an internal HDPE plastic pipe, and 4.06 g +/- 0.33 g with only a Fabreeka® pad. These results indicate that the deck is deflecting inward as trucks pass by, pitching the pole in a vector close to 45° away from the transverse axis. The peak accelerations occur as point pulses derived from axle loads as trucks pass by, resulting in sharp downward deflections and accelerations of the luminaire. At 55 mph, the average rise time for these pulses is about 8 milliseconds. Acceleration of the luminaire is a direct function of axle load and truck speed. Further testing is required to determine the effects of: (a) changing the pole material from aluminum to hot-dip galvanized steel or polymer composites; (b) adding sufficient mass for the luminaire counterbalance and precise direction for best vibration attenuation; and (c) increasing luminaire resistance to vibration at 5 g acceleration or more. Before any pole lighting is re-installed, it is imperative that luminaires be tested and approved by their manufacturers and the Illinois Department of Transportation to verify their resistance to 5 g vibration at a cyclic range of 1-10 Hz.]]></description>
      <pubDate>Tue, 23 Dec 2025 08:59:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2617972</guid>
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    <item>
      <title>Dynamic impact response and crashworthiness of luminaire pole-foundation systems in weak cohesionless soil</title>
      <link>https://trid.trb.org/View/2588456</link>
      <description><![CDATA[This study investigates the dynamic behavior and crashworthiness of luminaire pole and foundation assemblies under lateral impact loading in both dry and saturated weak soils through experimental and numerical methods. System-level dynamic bogie tests were conducted on a standard steel luminaire pole system anchored to a reinforced concrete foundation. These tests were performed under both soil conditions at an impact speed of 30 km/h, following the American Association of State Highway and Transportation Officials (AASHTO) Manual of Assessing Safety Hardware (MASH) guidelines. Structural damage, impact force, impulse, and lateral foundation displacement were measured to assess the performance and determine the activation thresholds for breakaway mechanisms. LS-DYNA-based numerical models, incorporating dynamic foundation-soil interactions and a strain-based material fracture formulation, were developed and validated against experimental results. These models facilitated analysis of foundation rotation resistance in weak soils and examined the impact behavior of assemblies with varying foundation embedment depths, aiming to optimize breakaway mechanism activation. Additionally, the crashworthiness and safety performance of the assemblies were evaluated using a small-sized vehicle, in line with MASH criteria.]]></description>
      <pubDate>Mon, 15 Sep 2025 10:34:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2588456</guid>
    </item>
    <item>
      <title>Evaluation of Structural Strength Characteristics of Light Pole Transformer Bases</title>
      <link>https://trid.trb.org/View/2567138</link>
      <description><![CDATA[Brittle cast aluminum transformer bases used as breakaway supports for luminaire poles to protect occupants during vehicular collisions, must also resist moments caused by lateral wind loads. To study its moment capacity, a three dimensional finite element model using CSA/NASTRAN was developed for analyzing both TB1-17 and TB3-17 t-base models. To validate the finite element results, full scale tests were conducted. The behavior of the t-base/light pole system is a complex interaction which is affected by properties of the t-base, base plate thickness, diameter of the pole and the diameters of the bolt circles at the top and bottom of the t-base. Critical loading orientations of the t-base were investigated and determined. The material properties of the cast aluminum, such as modulus of elasticity, ultimate tensile strength, and Rockwell hardness number, were investigated by testing specimens cut from the t-bases. Also, an attempt was made to correlate the material properties with the ultimate moment capacity of the t-base. For the use of field engineers, a simple interpolation computer program was developed to determine the ultimate moment capacity of transformer base/steel base plate system by inputting the actual base plate thickness, bolt circle diameters, t-base used and the steel pole diameter.]]></description>
      <pubDate>Mon, 08 Sep 2025 12:21:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2567138</guid>
    </item>
    <item>
      <title>Visibility Calculation from Video Images Using Different Techniques</title>
      <link>https://trid.trb.org/View/2567160</link>
      <description><![CDATA[Four different calculation methods were performed to determine the contrast of an STV target between illuminance assemblies mounted on poles: STV (small target visibility), STV with n points, STV by comparing the areas, and STV by patching. These experiments were performed under the original site conditions and after all the luminaire heads were replaced with new 250 Watt luminaires. The original conditions consisted of a combination of 250 Watt and 400 Watt lamps. Before replacing the luminaire heads, the target had 40% contrast. After replacing the luminaires with the 250 Watt luminaire heads, contrast increased to 85%. STV by patching was the least preferred method, and STV by comparing the areas was the second least preferred method for contrast calculation. STV was a poor method to calculate the contrast because of the small number of data points used for calculation.]]></description>
      <pubDate>Mon, 11 Aug 2025 16:31:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2567160</guid>
    </item>
    <item>
      <title>Research on the impact of the locations of luminaire failure on traffic safety in highway tunnels</title>
      <link>https://trid.trb.org/View/2569766</link>
      <description><![CDATA[The safety of highway tunnels hinges heavily on proper lighting infrastructure, yet luminaire failures pose an ongoing challenge. The study aims at assessing the impact of the locations of luminaire failures on highway tunnels safety. The research involved conducting 300 on-site scenarios with 29 participants, with simulated drives in visual recognition experiments. Multivariate analysis of variance (MANOVA) was applied to assess the individual effects of luminaire failures, luminous flux maintenance rates, and driving speeds on safety, as well as the between-group variability of these effects. Furthermore, Bonferroni tests were conducted to perform post hoc analyses, which determine the specific pairs of group means that differed significantly. Additionally, paired t-tests were used to analyze the impact of the failure locations. The results show that luminaire failures were the most significant factor affecting safety. Failures near the driver’s side had a more pronounced effect, and symmetric position of failures caused the most significant impact when the same number of luminaire failures occurred. The study also found that the distance between failed luminaires, rather than their specific positions, was the primary determinant of safety impact. Concentrated luminaire failures were more detrimental than scattered ones. The study concludes that concentrated luminaire failures present a significant threat to tunnel safety, emphasizing the urgency of accelerated maintenance to address such failures and uphold safety standards.]]></description>
      <pubDate>Tue, 29 Jul 2025 09:27:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2569766</guid>
    </item>
    <item>
      <title>Determining Vibrational Forces Experienced by High Pressure Sodium Vapor Lamps in Roadway Luminaires</title>
      <link>https://trid.trb.org/View/2561662</link>
      <description><![CDATA[The Texas State Department of Highways and Public Transportation has experienced difficulty in maintaining highway lighting integrity. High pressure sodium vapor (HPS) lamp outages, and problems with starter boards and ballast systems occurred on a regular basis. Many of these lighting failures could not be traced to poor installation/maintenance procedures or to lamp manufacturing defects. Laboratory tests were conducted at the TTI Research Annex at Bryan, Texas, to determine if HPS lamps were subject to vibration. The tests showed that induced vibrational forces up to 2 g caused "blink-out" and structural damage to one half of the lamps tested. The results from the laboratory tests were utilized to set instrumentation parameters necessary to conduct field tests. Based on the laboratory tests and visual observations in the field, it is postulated that: vibration causes dislodgement of amalgam which vaporizes and therefore requires more voltage to be supplied by the ballast to sustain the arc. If the vibration is severe enough, then sufficient amalgam is vaporized to require a greater voltage than the ballast is designed to supply, thus extinguishing the arc. This phenomenon is termed as "blink-out". No "blink-outs" were experienced at five test sites on Houston freeways, but tests were relatively short in duration. The test sites encompassed various pole and freeway configurations. Acceleration levels in pulse excitation, caused by close proximity traffic at speeds of 55 mph and more, often exceeded 1 g. In some instances acceleration levels approached and possibly exceeded 10 g.]]></description>
      <pubDate>Mon, 21 Jul 2025 10:00:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2561662</guid>
    </item>
    <item>
      <title>Determining Vibrational Forces Experienced by High Pressure Sodium Vapor Lamps in Roadway Luminaires (Supplement to Final Report)</title>
      <link>https://trid.trb.org/View/2561663</link>
      <description><![CDATA[This volume is intended as a supplement to the Final Report, Research Report Number 273-1F. Included are three reports prepared by project personnel from the Texas State Department of Highways and Public Transportation and from Texas A & M University. The reports explain the preliminary tests performed, test parameters, and test procedures. Also, included are test data, data analysis, explanations and recommendations. The reports contain many details not included in the basic report. This volume also includes a report by the General Electric Company entitled "Ballast Failures Caused by Defective High Pressure Sodium (H.P.S.) Lamps".]]></description>
      <pubDate>Mon, 21 Jul 2025 10:00:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2561663</guid>
    </item>
    <item>
      <title>Driving safety of low-position lighting in highway tunnels based on visual performance</title>
      <link>https://trid.trb.org/View/2564408</link>
      <description><![CDATA[To evaluate the lighting environment quality and driving safety of low-position lighting in highway tunnels, this study simulated three lighting schemes (high-position, low-position, and low-position with auxiliary LED strips on maintaining road) using DIALux software for a two-lane unidirectional tunnel. Key parameters for low-position luminaires were optimized, and drivers' obstacle recognition reaction times, gaze distribution patterns and pupil diameter dynamics were tested by visual performance experiments. The results indicate that the optimal parameters for low-position lighting, when using flat light technology luminaires better adapted to low-position lighting, are as follows: lamp spacing of 6–7 m, mounting height of 1.1–1.3 m, staggered arrangement, and auxiliary lighting power of 1 W/m. Compared to high-position lighting, low-position lighting reduced the threshold increment by 47.1%, increased small target visibility by 569%, and shortened drivers’ reaction times for near-roadway obstacles by 25%, significantly enhancing obstacle recognition. The pupil diameter variation rates across different lighting configurations all below 10% indicate that low-position lighting did not induce psychological states of tension or discomfort during driving. Although low-position lighting exhibited slightly lower longitudinal uniformity and longer reaction times for elevated targets, these limitations were effectively resolved by auxiliary LED strips. Overall, low-position lighting substantially improves driving safety and comfort in highway tunnels.]]></description>
      <pubDate>Thu, 26 Jun 2025 16:14:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2564408</guid>
    </item>
    <item>
      <title>Lighting Studies at Texas City Wye</title>
      <link>https://trid.trb.org/View/2543299</link>
      <description><![CDATA[The Texas City Interchange on Route 3 from Houston to Galveston was the subject of lighting research. The intersection was experimentally lighted with several arrangements of overhead luminaires so that many combinations of spacing and mounting heights could be employed. The visual effects of various combinations of lights from two of the approach directions are discussed in this publication.]]></description>
      <pubDate>Mon, 12 May 2025 12:02:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2543299</guid>
    </item>
    <item>
      <title>Optimized Pre-Tensioning and Re-Tightening Approaches for Anchor Rods for Highway Signs, Luminaires, and Traffic Signals (SLTS)</title>
      <link>https://trid.trb.org/View/2528609</link>
      <description><![CDATA[Previous studies and field investigations have demonstrated that anchor rods at the base of structural posts for Highway Signs, Luminaires, and Traffic Signals (SLTS) are susceptible to relaxation. This results in loosening of base connections and premature failure of such structural supports. On the other hand, re-tightening of anchor rods 48 hours after the installation requires significant resources, manpower, and additional costs. This implementation project aims to review past studies, systematically study the pre-tensioning methods and re-tightening procedures through experimental testing to fill the knowledge gap, and to propose an optimized method for pre-tensioning and re-tightening of anchor rod connections to result in acceptable relaxation, while minimizing the resources for doing so, and minimizing chances of over-tightening. In the end, the proposed methodology will be implemented in two local structural supports for SLTS in the state of Minnesota to evaluate the effectiveness of the proposed methodology.]]></description>
      <pubDate>Tue, 01 Apr 2025 16:33:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2528609</guid>
    </item>
    <item>
      <title>Accelerated Construction of Highway Steel Overhead Sign Truss (SOST) through the Implementation of U-Bolt Connections</title>
      <link>https://trid.trb.org/View/2490984</link>
      <description><![CDATA[The objectives of this research were to investigate the structural behavior of the U-bolt connections on an in-service steel overhead sign truss (SOST) structure, evaluate the loading through the U-bolt connections when the SOST was subjected to various wind directions, and compare the loading experienced by the in-service U-bolt connections with the capacities predicted by a 2019 Iowa Department of Transportation (DOT) study. To achieve these objectives, an in-service SOST structure in Iowa was selected and monitored on site for 10 months. The data collected during field monitoring were processed and analyzed. Following that, a finite element model was created utilizing the commercially available software Ansys to simulate the structural response of the SOST when subjected to wind loads. The data collected during field monitoring were used to determine the loads acting on the model and to validate the model. Further, the loads transferred through the U-bolt connections when the SOST structure was subjected to the design wind loads were calculated and compared with the U-bolt capacities predicted by a 2019 Iowa DOT study. The yield and ultimate U-bolt capacities predicted by a 2019 Iowa DOT study were compared to the Service I and Extreme I design wind loads calculated using the AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals. The comparison indicates that of all of the Type A U-bolt connections, only the U-bolt types with high yield strengths have yield capacities greater than the imposed stress. The 2019 Iowa DOT study indicated that the yield capacity of a U-bolt connection is low due to the complex geometry, and stress concentrations occur when loading is low. Conversely, the ultimate capacities are greater than the Extreme I wind loads because a U-bolt connection exhibits good ductility before reaching failure.]]></description>
      <pubDate>Tue, 28 Jan 2025 14:52:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2490984</guid>
    </item>
    <item>
      <title>The Application of 2k Factorial Design to Determine the Luminance in Truck Parking Lots</title>
      <link>https://trid.trb.org/View/2487378</link>
      <description><![CDATA[Road freight is a main mode of transportation in the logistics system, and its operation substantially depends on the heavy goods vehicle (HGV) trucks. One of the places, where trucks drivers spend hours in the long-haul route, is the parking lot. As a result, the safety matter in truck parking lots is important to the efficient performance of trucks in the system, especially during the night time. The enough amount of light significantly contributes to the safety of both drivers and pedestrians in the parking lots. This research focused on the optimal design of lighting installation in the target truck parking lot. The first stage of this study was the survey of the available truck parking lots, and the layout of the selected lot was used as the input of the simulation program. Afterwards, DIALux software was used to simulate the luminance for the chosen layout. To carry out the empirical study, a statistical design method, 2ᵏ full factorial design, was utilised to determine the relationship between design parameters and two responses, average luminance (L[subscript av]) and overall uniformity ratio (Uo). The design parameters were categorized into three groups, luminaire (LED wattage), the placement of pole (spacing, height, boom angle, and overhang), and pavement reflectance (average luminance factor or Q[subscript 0]). The analysis results showed that all designed parameters had a significant effect on Lav. There were also effects from two interactions, height*Q[subscript 0] and boom angle*Q[subscript 0]. Moreover, Uo was considerably influenced by all parameters except wattage. Another important finding was that the following setting, spacing (low) and Q[subscript 0] (high), should lead to the maximization of L[subscript av] and Uo. Finally, the validation stage was carried out by applying the optimal setting with the lighting design on a different truck parking layout. The empirical and validation results signified that the setting of design parameters for the highest L[subscript av] also led to the acceptable level of Uo as well. In practice, the research results can assist lighting designers to improve the design of a lighting system, so it would provide the adequate amount of light for truck parking lots.]]></description>
      <pubDate>Mon, 27 Jan 2025 08:55:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2487378</guid>
    </item>
    <item>
      <title>MASH Testing of Luminaire Pole behind Single Slope Traffic Rail</title>
      <link>https://trid.trb.org/View/2475940</link>
      <description><![CDATA[The purpose of the test reported herein was to assess the performance of a luminaire pole mounted behind a single slope traffic rail according to the safety-performance evaluation guidelines included in the second edition of the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH) (1). The crash test was performed in accordance with MASH Test 4-12, which includes a 10000S vehicle weighing 22,000 lb impacting the longitudinal barrier upstream of the luminaire pole while traveling at a nominal speed of 56 mi/h and nominal angle of 15 degrees. This report provides details of the Luminaire Pole behind Single Slope Traffic Rail, the crash test and results, and the performance assessment of the Luminaire Pole behind Single Slope Traffic Rail for MASH Test 4-12 evaluation criteria. The Luminaire Pole behind Single Slope Traffic Rail met the performance criteria for MASH Test 4-12.]]></description>
      <pubDate>Mon, 16 Dec 2024 09:12:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2475940</guid>
    </item>
    <item>
      <title>Evaluating Crashworthiness of Sign Supports and Breakaway Luminaire Poles: Appendices</title>
      <link>https://trid.trb.org/View/2452784</link>
      <description><![CDATA[The objective of this project was to evaluate selected systems and propose modifications to the Manual for Assessing Safety Hardware (MASH) to provide additional guidelines on selecting a critical test matrix for testing families of systems. Given the time and budget constraints, the two most common categories were selected for evaluation: (1) a breakaway steel luminaire pole with aluminum TB1-17 frangible transformer base and (2) a single 2¼-in. 12-gauge PSST steel sign support. LS-DYNA models for the pole and PSST systems were developed and partially validated using the available crash tests. Nine and seven full-scale crash tests were recommended for the pole and PSST families of devices. Because additional budget was needed to run all necessary crash tests, it was decided to provide guidelines regarding the crashworthiness of both families as best as possible. This document contains the appendices to the research report (NCHRP Research Report 1123: Guidelines for Evaluating Crashworthiness of Sign Supports and Breakaway Luminaire Poles).]]></description>
      <pubDate>Mon, 18 Nov 2024 17:16:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2452784</guid>
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