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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <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>Spectral noise reduction of double-layer porous asphalt: From laboratory to field</title>
      <link>https://trid.trb.org/View/2422240</link>
      <description><![CDATA[The double-layer porous asphalt (DLPA) pavement is a practical way to mitigate traffic noise from the source. However, there hasn't been much research done on the spectral noise characteristics of the car/truck on this type of pavement with different surface conditions yet. The objective of this paper was to reveal these noise characteristics and the behaviors of the DLPA pavement by laboratory tests and field measurements. First, measurements were made of the road performance of different porous asphalt (PA) mixtures and DLPA structures. Then, a vector impedance measurement system was utilized to evaluate the effects of porosity, aggregate size, and thickness on the sound absorption coefficient (SAC) of the DLPA slabs. Third, a sound meter was used to record the noise levels outside/inside the car/truck on the roads with three surface conditions for the DLPA (PA-10+PA-20) and stone matrix asphalt (SMA) test section, which were paved on an elevated urban road. Finally, an analysis was done on the overall and spectral noise characteristics. The results demonstrated good road performance of these PA mixtures and DLPA structures. Relatively fine and coarse aggregates in the upper and lower layers, respectively, enhanced the sound absorption. But an increase in porosity beyond 20 % and a slight variation in thickness did not considerably improve the sound absorption. Compared to SMA pavement, the overall noises levels of the DLPA pavement were 4–8 dBA lower on the “dry” surface and 6 dBA lower on the “wet” surface. The DLPA pavement exhibited a noise reduction at the full frequency band, which attributed to the pore structure and the relatively fine aggregate used. The interior sound energy always concentrated on the low-frequency band. However, the exterior sound energy on the “dry” and “wet” road surfaces tended to the low-frequency and high-frequency bands, respectively. These findings would shed light on the spectral noise characteristics of the DLPA pavement and provide a new knowledge about the behaviors of the lower layer and upper layer in relation to noise reduction and road performance.]]></description>
      <pubDate>Fri, 13 Sep 2024 10:34:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2422240</guid>
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    <item>
      <title>Airless Tires in the LEON-T Project: How Can They Be Modelled?</title>
      <link>https://trid.trb.org/View/2335020</link>
      <description><![CDATA[For more than a century, pneumatic (air-inflated) tires have totally dominated the market for road vehicle tires. However, in the recent two decades, interest has grown in developing airless tires. Some of the authors were involved in design of an early version in composite material 15-30 years ago for passenger cars. Presently, the EU project LEON-T (Low particle Emissions and lOw Noise Tyres) includes a part in which prototypes for innovative heavy goods vehicle (HGV) tires are developed, with the main purpose to reduce noise emission by 6 dB. To reduce noise that much it is believed that airless tires are needed. A special challenge is to get a durable design able to carry typical truck tire loads.This paper introduces the principal design of airless tires. Airless tire prototypes are intended to be developed by partner Euroturbine, in cooperation with mainly Applus+ IDIADA, VTI and subcontractor Lightness by Design. The tire consists of a rim, load-carrying spokes, composite belt, and rubber tread. The primary focus is on the modelling of static and dynamic behavior of the tire and the corresponding impact on the tire design.By aid of FE modelling, the tire static behavior (radial, lateral, and longitudinal stiffness) is analyzed. It is found that the radial stiffness of the modelled tire is within the ranges of that of a conventional pneumatic tire, however, the longitudinal and lateral stiffnesses are 2.5 and 2 times higher, respectively. The same tire model is used to study its dynamic behavior (modal and noise characteristics) which are then compared with that from measurements. For modal studies, the point inertances are used as a reference for test and simulation validation. The same for the noise study is the noise transfer function that is measured at a predetermined location, using a microphone in the vicinity of the tire.]]></description>
      <pubDate>Wed, 07 Feb 2024 11:27:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2335020</guid>
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    <item>
      <title>An autonomous and heuristic approach for extracting bridge frequencies from passing vehicles</title>
      <link>https://trid.trb.org/View/2189655</link>
      <description><![CDATA[The Federal Highway Administration (FHWA) recognizes a need for cost-effective and practical structural health monitoring (SHM) techniques to manage the bridge network. System identification (SI) techniques are the first step in developing SHM frameworks to extract bridge dynamic properties (natural frequencies, damping ratios, and mode shapes). One promising indirect SI technique uses accelerometer-instrumented vehicles to measure the dynamic properties of bridges, such that a few instrumented vehicles could economically monitor a large network of bridges. This study proposes an autonomous framework called autonomous peak picking variational mode decomposition (APPVMD), which leverages an ensemble of signal processing techniques and heuristic models to autonomously extract bridge frequencies from instrumented vehicles. The proposed framework does not require prior information or model-informed training. The framework is tested on four vehicles and 39 unique bridge classes using finite element (FE) models to assess the feasibility of deploying it into practice. The results of this study indicate that the algorithm can make successful bridge frequency extractions in more than 69.2% of the bridge cases using any vehicle and a maximum value of 97.4% using an SUV, while considering the effects of road surface roughness. The influence of bridge stiffness, mass, and span length on the algorithm’s success rate is discussed. It is concluded that flexural rigidity and span length play a significant role in the accuracy of APPVMD. The combined effects of bridge inertia and damping cause heavier bridges to have a higher amplitude signal for a longer duration, increasing the algorithm’s successful detection rate of bridge frequency. Next, the authors examine the effect of reducing the tire stiffness in the truck model on the success of the APPVMD algorithm. The customized truck outperformed the original truck and the SUV by successfully extracting the bridge frequencies of 97.4% of the bridge cases and by having more bridge frequencies predicted in a higher confidence region than the SUV. In addition, the customized truck model is used to verify the APPVMD’s robustness to large levels of sensor noise. Even at significant levels of white noise (1% SNR), as the success rate for bridge frequency extraction using the customized truck only drops to 84.6%. Finally, the influence of vehicle speed on the APPVMD algorithm’s effectiveness is studied. Generally, slower speeds resulted in more successful predictions of bridge frequency, but minor improvements in the accuracy of the frequency predictions were observed at slightly increased velocities, 13.4 m/s (30 mph) and 17.9 m/s (40 mph), but a reduction in accuracy was observed at higher velocities, 22.3 m/s (50 mph).]]></description>
      <pubDate>Wed, 19 Jul 2023 09:38:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2189655</guid>
    </item>
    <item>
      <title>Rumble Strip Design Analysis to Contribute to Low Exterior Noise Using Finite Element Modeling</title>
      <link>https://trid.trb.org/View/2004798</link>
      <description><![CDATA[Optimal rumble strips/stripes are critical to ensure traffic safety and simultaneously avoid disturbance to the surrounding environment. In this project, the authors have utilized a commercial Finite Element modeling tool to calculate the amount of noise in the tires while rolling over the rumble strips. The sound level is determined within the tire cavity. The authors have evaluated three types of designs: conventional, sinusoidal, and sawtooth. In total, they have simulated 19 conventional designs, 21 sinusoidal designs, and 6 sawtooth designs at 3 varying vehicle speeds for a passenger car and a truck tire. The authors have observed that the sinusoidal designs produced lower sound outputs than the conventional designs, and the sawtooth designs with a longer wavelength produced similar sound outputs to a sinusoidal design at the same depth. Furthermore, they have developed a non-zero angle of landing for different conventional and sinusoidal designs. Overall, the numerical simulations produced expected trends in the sound outputs for different rumble strip dimensions. Furthermore, when a chosen sound output level is determined, a specific dimension can be found among the simulated cases to guide the construction.]]></description>
      <pubDate>Wed, 24 Aug 2022 15:05:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2004798</guid>
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    <item>
      <title>Smooth Road Shake Reduction in Pickup Trucks Using Hydraulic Body Mounts</title>
      <link>https://trid.trb.org/View/1830841</link>
      <description><![CDATA[The advantages of hydraulic mounts over conventional elastomeric mounts for NVH refinement are well known, particularly in the area of engine and suspension mounts. Recently, hydraulic mounts have been successfully employed as body mounts between the frame and cab, principally to control freeway hop in pickup trucks. Due to their ability to provide increased damping at small displacements, hydraulic body mounts also have good potential to reduce smooth road shake. This paper documents the reduction in smooth road shake performance of a full size pickup truck. Hydraulic body mounts tuned to the frequency of the smooth road shake sensitivity area were added to the rearmost cab mount location. Both tire-wheel balance and uniformity were set to the highest production level specification allowed and the effect of hydraulic cab mount was measured experimentally during smooth road driving at medium to high speeds. Hydraulic body mounts were found to be successful in reducing smooth road floor shake by up to 6 dB, thereby considerably refining the vehicle vibration due to first order tire-wheel input forces. Additional benefits for freeway hop and ride comfort on rough road were also realized with the hydraulic body mounts.]]></description>
      <pubDate>Mon, 18 Jul 2022 09:25:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1830841</guid>
    </item>
    <item>
      <title>Measured Effect of Low-Height Solid Safety Barriers on Heavy Truck Noise</title>
      <link>https://trid.trb.org/View/1988748</link>
      <description><![CDATA[Low-height solid safety barriers (SSBs) are constructed along highways where an adequate clear zone cannot be provided between the highway and an important roadside feature. Where a roadside SSB is a permanent installation, it is possible that it also provides noise reduction benefits. Highway traffic noise sources that could be shielded by a low-height SSB include tire–pavement noise and any other noise originating close to the pavement surface, such as a low exhaust on a heavy truck. This paper reports the findings of a study examining how heavy truck noise is shielded by low-height roadside SSBs. Measurements of the maximum sound level (Lmax) of individual heavy truck pass-by events at two representative locations in Ohio were obtained at a position where a low-height SSB was present as well as at a nearby unshielded position. The results indicated that a perceptible reduction in the pass-by event Lmax (between 3 and 5 dBA) was realized for locations behind the SSBs. Variations in the measured noise reduction were associated with the line-of-sight shielding between various truck noise sources and the receiver positions. For events in which the exhaust source was shielded by the SSB, the measured noise reductions were higher at the site with the 42-in. tall SSB, although there was no difference for the site with the shorter (32-in.) SSB. It is recommended that analysts consider the potential for noise reduction associated with low-height SSBs in locations where such barriers are expected to be permanent.]]></description>
      <pubDate>Wed, 06 Jul 2022 09:07:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1988748</guid>
    </item>
    <item>
      <title>Reviewing the REMEL Noise Database to Accommodate the Current Vehicle Fleet



</title>
      <link>https://trid.trb.org/View/1957104</link>
      <description><![CDATA[Highway noise is always a top environmental concern with the public on any highway project. The Reference Energy Mean Emission Level (REMEL) database is an inventory of different vehicle pass-by noise levels that is the basis for the Federal Highway Administration (FHWA) Traffic Noise Model (TNM) analysis software. It is 25 years old and in need of updating due to changing vehicle fleet characteristics. Newer noise measurement technology has also evolved, and it can be applied to locate and quantify noise generators on a moving vehicle. The REMEL database directly affects noise impact and mitigation analyses on federal-aid projects. 
Research is needed to update the highway noise dataset using existing and new highway acoustic measurement technologies to account for the change in the vehicle fleet. 
OBJECTIVE: The objective of this research is to update the REMEL noise database to account for new vehicle fleet with focus on: Newer passenger car (PC) types; Medium truck (MT); Heavy truck (HT); and Electronic vehicle (EV). 
At a minimum, the research team should use three acoustic measurement technologies (beamforming, wayside sound level, and on-board sound intensity (OBSI)) that will better quantify the position and distribution of vehicle noise sub-sources: mechanical, exhaust, tire/pavement, and aerodynamic sources. 
]]></description>
      <pubDate>Tue, 24 May 2022 11:08:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1957104</guid>
    </item>
    <item>
      <title>Determination of Heavy Truck Noise Sources under Actual Highway Operating Conditions Using Acoustic Beamforming</title>
      <link>https://trid.trb.org/View/1835623</link>
      <description><![CDATA[Acoustic beamforming was used to localize noise sources on heavy trucks operating on highways in California and North Carolina at a total of 20 sites. Over 1,200 trucks were measured under a variety of operating conditions, including cruise on level highways, on upgrades, down degrades, low speed acceleration, and for various speeds and pavements. The contours produced by the beamforming measurements were used to identify specific source contributions under these conditions and for a variety of heavy trucks. Consistently, the highest noise levels were seen at the tire-pavement interface, with lesser additional noise radiated from the engine compartment. Noise from elevated exhaust stacks was only documented for less than 5% of the trucks measured. The results were further reduced to produce vertical profiles of noise levels versus height above the roadway. The profiles were normalized to the highest noise level at ground level. The profile averages from each measurement site were found to be independent of speed and operating conditions and were consistent from site-to-site. The highest levels were also related to the tire-pavement noise measured, independently, using on-board sound intensity methods. The results of this research are presented, and their implications for highway noise and noise modeling are discussed.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:38:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1835623</guid>
    </item>
    <item>
      <title>Study on the Handling Stability for an Articulated Truck with Four Motor-Driven Wheels</title>
      <link>https://trid.trb.org/View/1835618</link>
      <description><![CDATA[Articulated engineering vehicle travels on complex road, its working condition is bad and because of the non-rigid connection between the front and rear body, additional DOF is brought in and the transverse stiffness is relatively weak. When the articulated vehicle runs in a high speed along a straight line, it is easy to cause the transverse swing and the poor handling stability. If it is serious enough, it will lead to "snakelike" instability phenomenon. This kind of instability will increase driving resistance and tire wear, the lateral dynamic load and aggravate the damage of the parts. The vehicle will have a lateral migration of center of gravity (CG) when steering, which will lead a higher probability of rollover accident. A dynamic mathematical model for a 35t articulated truck with four motor-driven wheels was established in this paper, to study the condition for its stable driving and the influence of the vehicle structural parameters. This part research focused on the position changes of the pivot and front and rear axle center, which impact the handling stability. Then a multi-body dynamic model was built in ADAMS and simulation of steady state circular test and steering wheel angle step input test were conducted to observe the handling stability of vehicle and compare the results in empty load, full load and different steering angle step inputting. On this basis, the influence of the CG position of rear body on truck handling stability was studied. The results of simulation has a good reference value for the articulated truck handling stability design and verify the correctness of the models.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:38:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1835618</guid>
    </item>
    <item>
      <title>Recent Development in Europe Aiming at the Reduction of Exterior Vehicle Noise by Producing Quieter Vehicles, Tires and Pavements</title>
      <link>https://trid.trb.org/View/1827524</link>
      <description><![CDATA[This paper summarizes a presentation that attempts to describe what has recently been done and is planned to be done to relieve the problem of traffic noise, with focus on tire/road noise emission. The paper shows that there is at the moment in Europe, Japan and in countries accepting ECE Regulations a quite intensive development aiming at reduction of road traffic noise, but with initial high ambition often ruined when it comes to the political process. The author thinks that it is likely that many Asian countries under fast development will adopt similar policies as Europe and Japan, although actual implementation may be slower than formal policies would suggest. This positive development applies to exterior noise from light vehicle power units, from car tires and from pavement properties. The exception is trucks and buses and their tires, which are left without significant improvement in the foreseeable future and thus may have an effect on the future perception of truck traffic. In addition, the unique opportunity to reduce traffic noise in urban settings by the gradual introduction of electric and hybrid/electric vehicles may be ruined by addition of extra sound to such vehicles in order to make them easier heard.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:35:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1827524</guid>
    </item>
    <item>
      <title>Heavy Duty Truck Driveline Optimization using Six Sigma Methodology</title>
      <link>https://trid.trb.org/View/1816673</link>
      <description><![CDATA[Fuel consumption for heavy trucks depends on many factors like roads, weather, and driver behaviour that are hard for a manufacturer to influence. However, one design possibility is the power-train configuration. In this paper, driveline of a heavy-duty truck is optimised using the six-sigma methodology. The focus of the task is selection of a power train configuration that gives the lowest fuel consumption for each transportation task. To reduce fuel consumption, it is important to choose a powertrain combination (gearbox, rear axle, tire dimension) that allows efficient use of the engine. Such an optimization of powertrain configuration is a complex task, but current simulation techniques provide means to reduce costly testing by replacing it partly with analysis.         The DMAIC (Define, Measure, Analyze, Improve & Control) steps are followed to generate alternate solutions of the descriptive problem. In order to benchmark and improve over the current scenario, data is collected from various vehicles operating in the field and the sigma rating is calculated. The Design of Experiments (DoE) is performed considering the factors such as Engine type, Gearbox type and final drive ratio. A full factorial method of DOE is developed and simulations are executed using the AVL Cruise® software for the selected combinations. In this work, the operational conditions have been considered i.e. load, pavement, transmission efficiency and the building characteristics of the engine map, transmission, frontal area, and tire. The traffic conditions and the transmission efficiency of the driveline are considered as noise factors and the variation in the kmpl due to these noise factors are studied. This has led to robust design of the prediction model. All the statistical evaluations have been carried out using Minitab v15 ®.         SIX SIGMA is an efficient and methodological procedure to evaluate and rationalize results to select the desired combination. The final combination selected through statistical and physical significance, was tested and improvements as expected in the theoretical calculations were observed. A design methodology for selecting the right kind of driveline for a heavy-duty truck has been established. Furthermore, on evaluation of the test results of the proposed driveline, a statistical measure of fuel mileage considering the chance causes is established in terms of mean and standard deviations.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:33:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1816673</guid>
    </item>
    <item>
      <title>An Investigation of Vehicle HVAC Cabin Noise</title>
      <link>https://trid.trb.org/View/1815354</link>
      <description><![CDATA[Noise and vibration have an important influence on a customer's perception of vehicle quality and cabin interior noise levels are a key criteria. The interior sound levels of automobiles have been significantly reduced over the years, with reductions in power train, tire and external wind noise. One of the highest in-cabin noise levels now arises from heating, ventilating and air conditioning systems, generated by the air-rush noise at various HVAC settings. Thus quieter climate control systems are desired by car manufacturers.         A systematic benchmarking study was performed to investigate the in-cabin noise of vehicles. 21 passenger cars including compact, mid-size, full-size, and a truck were selected. Tests were conducted on relatively new production vehicles in various conditions. A binaural head system was used in front passenger seat to measure noise levels. The methodology used and the experimental results were presented in this paper.         It was found that the design of the HVAC system has a major influence on the vehicle in-cabin acoustic performance. The size/price of the vehicle may not correlate to the cabin quietness due to the complexity of acoustic effects in the HVAC system.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:33:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1815354</guid>
    </item>
    <item>
      <title>Influence of Road Speed Humps on Vehicle Ride Dynamics with Active Suspension Designed with GA</title>
      <link>https://trid.trb.org/View/1812327</link>
      <description><![CDATA[Road humps are considered as one of the best design propositions to control running vehicle speeds, in many roads they are randomly installed depending on the resident's requirements. In this paper, Genetic Algorithm (GA) optimization technique is used to design an active suspension based on force cancellation concept when the vehicles crossing road humps. A longitudinal half vehicle model is used to represent passenger's car and truck models. These models are used to evaluate the performance of active suspension over the road speed humps. The force cancellation concept is employed to isolate the force between the sprung and unsprung mass. Virtual damper and skyhook damper concepts are also used for reducing the sprung mass acceleration and tire dynamic loads. GA is adopted to obtain the better coefficients of a virtual damper and a skyhook damper for its effective searching ability. The results are generated in time domain and represented as a root mean square values (RMS) and bar charts.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:32:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1812327</guid>
    </item>
    <item>
      <title>The Influence of Truck Tire Type and Pavement on the Emission of Noise from Trucks under Highway Operating Conditions</title>
      <link>https://trid.trb.org/View/1812279</link>
      <description><![CDATA[Typically, the noise emission from trucks under highway cruise conditions is not reduced as much as it is for light vehicles when quieter pavements are used. Potential reasons for this are that other noise sources beside tire/pavement noise are more significant for trucks than light vehicles and/or the effect of pavement on truck tire noise generation is different than it is for light vehicle. As the cruising passby noise levels of trucks are about 10 dB greater than for light vehicles, this becomes an important issue for highway noise abatement when trucks make up even a relatively small percentage of the traffic flow. To investigate this issue, beam forming and conventional passby testing methods were used to investigate the contribution of both tire/pavement noise and the other noise sources for common types of heavy trucks. To isolate the tire/pavement effects, the onboard sound intensity (OBSI) measurements were made on a variety of asphalt surfaces using a passenger car tire and seven different truck tire designs. The results from both of these studies suggest that while other sources on trucks are important, differences in the way that some truck tires respond to pavement changes may be an appreciable factor in the differential effect of quieter pavement on cars and trucks.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:32:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1812279</guid>
    </item>
    <item>
      <title>A Simple Model for the Simulation of Low-Frequency Disc Brake Noise</title>
      <link>https://trid.trb.org/View/1812122</link>
      <description><![CDATA[A simple ADAMS model was developed for simulating one possible mechanism that causes low-frequency (less than 1 kHz) noise in disc brake assemblies for heavy-duty and medium-duty trucks. The model consists of: truck tire, axle housing, torque plate, caliper, push rods, inner pad, outer pad, and rotor. Only one component (the torque plate) was modeled as a flexible body (using a finite element model), while all other parts are considered as infinitely rigid. A lumped parameter representing the suspension wrap-up stiffness resists the axle pitch motion. When the brakes are not engaged, the system has two distinct modes of vibration, namely, the axle pitch mode which is governed by the suspension wrap-up stiffness, and the caliper transverse (side-to-side) mode, which is governed by the stiffness of the torque plate (out-of-plane deflection of the torque plate) and by the suspension lateral stiffness. When the brakes are engaged, there is a possibility that the two vibration modes may coalesce into one system mode of vibration, the frequency of which is distinct from any of the two underlying modes of vibration. The probability of the occurrence of this mode coalescence primarily depends on the compressibility (compliance along the direction of the normal contact force) of the friction pads.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:32:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1812122</guid>
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