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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>
    <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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    <item>
      <title>Flammability test procedure development for motor vehicle interior materials</title>
      <link>https://trid.trb.org/View/2705998</link>
      <description><![CDATA[This paper summarizes the results of a research program conducted at Southwest Research Institute for the U.S. Department of Transportation National Highway Traffic Safety Administration. This is a follow-on project to previous work in which an alternative methodology was developed for evaluating flammability of interior automotive materials based on the Microscale Combustion Calorimeter. The main goal of the previous project was to improve the repeatability and reproducibility of evaluating the flammability of interior materials that are difficult to test per Federal Motor Vehicle Safety Standard No. 302. The objectives of the follow-on program are as follows: (1) further verify the validity of the alternative methodology for a wider range of interior materials, (2) evaluate and improve the repeatability of flammability assessment for layered and other multi-component materials, (3) compare the assessment of materials using the alternative method to evaluations based on Mass Loss Calorimeter data, and (4) develop performance criteria for use with the alternative method to achieve the minimum safe egress time from large buses. The paper concludes with some recommendations for future work.]]></description>
      <pubDate>Tue, 26 May 2026 09:38:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2705998</guid>
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    <item>
      <title>Study of sound patterns and sound perception in electrified trucks</title>
      <link>https://trid.trb.org/View/2534226</link>
      <description><![CDATA[During the process of development of electric heavy vehicles the focus on sound quality have become much more important. Shifting the internal combustion engine to electric propulsion, has not only decreased the sound levels. The sonic character is now more tonal and needs other evaluation routines and new target settings. The purpose of this work is to define applicable methods and target values to, in the long term, secure good sound quality and safe vehicles. To accomplish this mission several sub-questions needs to be investigated such as perception of prominence and loudness of complex tones, underlying aspects for evaluation of sounds as well as behavioural effects and comfort during driving. In the present work, listening tests were made to study how the number of tone components and frequency intervals between the components affect the perception of the perceived loudness of complex tones. The listening tests revealed that there is a linear relationship between perceived loudness and increasing number of harmonics of a complex tone with amplitudes of the partials decreasing 6 dB per octave. To study underlying aspects for sound assessments, qualitative data from a previously performed listening test on a first-generation battery electric truck was studied. The method of thematic analysis was used to derive information about what decided if a sound was evaluated as positive or negative. Various aspects have an impact on the outcome. Interrelation between tonal components needs to be considered when setting targets on sounds with complex tonal content to give valid estimations of loudness and prominence. Subjective evaluation of dynamic driving operations depends of several different factors. These are connected to the individual such as listening and contextual experience, individual values and preferences, hearing function, relation between feedback and input as well as acoustical features. Informative sounds with close connection to load and speed are desirable.]]></description>
      <pubDate>Fri, 04 Apr 2025 15:15:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2534226</guid>
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    <item>
      <title>Energy efficient air quality solutions for vehicle cabins</title>
      <link>https://trid.trb.org/View/2344853</link>
      <description><![CDATA[Maintaining a good air quality level is essential for reducing potential health risks for human beings. Vehicle cabin is one common environment where people spend increasing amount of time in modern societies. It’s an environment challenged by elevated pollutants from surrounding traffics, especially small particles like PM2.5 and UFP (Ultrafine particles). To efficiently reduce or remove the pollutants from incoming air is one essential focus for development of future vehicles. To achieve that goal with energy efficient solutions would be even more important in the trend of emerging electric vehicles. The objective of this thesis is to evaluate and propose solutions for improved cabin air quality and energy efficiency, which could be used in the development of vehicle climate system. The work has been conducted through vehicle measurements on road in two different locations, development of an air quality model, modelling of increased recirculation in the climate ventilation strategy, as well as measurements on new prototypes in both rig and road conditions. The purpose of the road measurements is to set the baseline of current air quality levels and evaluate the important influencing factors such as filter age and ventilation settings. The purpose of the model development is to enable a repeatable and comprehensive evaluation environment, which is later used to evaluate the strategy of increased air recirculation under common driving conditions. The purpose of the measurements on prototypes is to evaluate one solution of using EPA (Efficient Particulate Air) or HEPA (high-efficiency particulate air) filters as pre-filters, to prove the concept and the limitations.]]></description>
      <pubDate>Tue, 27 Feb 2024 14:27:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2344853</guid>
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    <item>
      <title>Fire safe bus interior materials : flame retardants and the effect on smoke production and smoke gas toxicity</title>
      <link>https://trid.trb.org/View/2337119</link>
      <description><![CDATA[The demands on bus interior products have increased with increasing sustainability, circularity and a reduction of harmful substances, today’s materials must be improved with regards of additives, such as flame retardants. A comprehensive study was made to evaluate the possibility to use phosphorous flame retardants (FRs) instead of the commonly used halogenated FRs compounded with ABS. The study showed that the fire performance could be improved with phosphorous FRs regarding heat release and smoke production. However, it was noted that the smoke production still was high, and that the smoke density was highest possible, i.e., no visibility through the smoke layer. Further testing of today’s bus interior materials showed that the high smoke density was achieved already after a few minutes of test time. Thus, it can be concluded that, in case of a fire, the visibility in the bus will be reduced and limit the ability of the passengers to safely evacuate. In addition, several toxic gases were detected in the smoke, both irritants and suffocating gases. The bus fire regulation R118 for interior materials basically deals with burning rate and melting through a fine mesh. Critical fire parameters such as smoke production and smoke toxicity is not dealt with. The R118 regulation need to be improved with these critical parameters in order to have fire safe materials inside the bus.]]></description>
      <pubDate>Thu, 08 Feb 2024 08:39:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2337119</guid>
    </item>
    <item>
      <title>Development of toxicity assessment method for bus interior materials</title>
      <link>https://trid.trb.org/View/2337118</link>
      <description><![CDATA[In recent years, fire safety requirements for bus interior materials have been increased and introduced into international regulations. Fire safety requirements for the burning rate, melting and dripping behaviour of interior materials already exist for many years. However, it remains unclear to what extent the release of smoke, combustion products and their toxicity should be limited. Therefore, a research and development project 82.0723 funded by BASt (Federal Highway Research Institute) was initiated to develop a simplified procedure for testing the toxicity and smoke development in case of fire of interior materials used in buses. The scope of the research included calculations to assess the toxicity of fire gases and the derivation of specifications for the formation of practicable limit values for smoke toxicity. Further investigations are needed to derive these limit values for smoke toxicity in order to be applicable for real fire scenarios in buses.]]></description>
      <pubDate>Thu, 08 Feb 2024 08:39:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2337118</guid>
    </item>
    <item>
      <title>Front seat passengers' experience of ride comfort and NVH in modern cars</title>
      <link>https://trid.trb.org/View/2145729</link>
      <description><![CDATA[Due to the refinements in combustion-engine and electric cars, ride comfort has become a prominent attribute when it comes to developing cars in the future. A variety of factors, such as seat, seatbelt, sound and vibration, have been shown to influence perceived overall ride comfort in passenger cars. Numerous studies have investigated human responses to sound and vibration. However, few studies have investigated passengers’ experiences of sound and vibration in real passenger cars, in different real-world driving scenarios. The purpose of this licentiate thesis is to identify human experiences of sound and vibration in modern passenger cars. An approach has been developed to investigate how sound and vibration influence overall perceived ride comfort in combustion-engine cars (CVs) and electric cars (EVs). The first research question relates to the definition of ride comfort, from the passenger’s perspective, and the methodology used to specify the factors that influence overall ride comfort. The second research question deals with specifying how ride comfort is influenced by sound and vibration. The research includes literature reviews of human responses to sound and vibration and a user study using a mixed-method research approach that focused on subjective judgements and objective measurements of overall ride comfort. The literature reviews found that several laboratory studies have covered the level and frequency ranges of interest for vibration and sound found in passenger cars. Other studies have employed realistic ride postures with populations of various ages, gender and anthropometric measures to investigate the influence of vibration on ride comfort. Studies of sound in passenger car have explored approaches to identify sound sources, assess sound quality and design product sound. The overall conclusion from the literature reviews was that there is a lack of studies that consider all the different parameters influencing the overall ride comfort experience of automotive vehicle passengers. Also, further studies are specifically needed to investigate the influence of sound and vibration on passengers’ experience of overall ride comfort.]]></description>
      <pubDate>Mon, 03 Apr 2023 16:46:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2145729</guid>
    </item>
    <item>
      <title>Psychoacoustic perspectives on electric truck</title>
      <link>https://trid.trb.org/View/2093196</link>
      <description><![CDATA[The soundscape is constantly changing, and new sounds are added to the soundscape. To localize sources, we rely both on binaural and monaural cues, and the auditory system also provides distance to sound sources. This paper gives an outline of the planned work of determining the interior sound quality within electric heavy vehicles.]]></description>
      <pubDate>Tue, 03 Jan 2023 14:20:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2093196</guid>
    </item>
    <item>
      <title>CO2 project – CO2 effects on drivers’ state and performance</title>
      <link>https://trid.trb.org/View/2075225</link>
      <description><![CDATA[Moderate-high CO2 levels have been detected inside vehicles driving with the HVAC unit (heating, ventilation and air conditioning) in recirculating mode (RC). This system is often used to reduce the inflow of pollutants from outside (e.g., when traffic is congested) and/or maximize the air conditioning effects, especially during the summer. In e-cars, drivers also activate the RC to reduce energy consumption when cooling down the warm air from outside. A consequence of enabling the RC system, however, is a rapid build-up of respiration-derived CO2 due to a lower air exchange rate. In fact, different studies have detected moderate-high CO2 levels (1000 – 5000 ppm) after just a few 5-10 minutes of driving. This evidence suggests that a large number of drivers may frequently expose themselves to CO2 concentrations that could affect their state and, more importantly, their ability to drive safely. This potential effect, however, has received no attention in the literature. To address this knowledge gap, the present project aimed to elucidate the possible effects of moderate high CO2 levels on driver fitness and performance. In addition, this project analyzed the influence of other factors, such as driver mental workload and driving time, on the effects of CO2. This second objective builds on the idea highlighted by two recent reviews that CO2 effects may be more easily detectable when task demands are sufficiently high. Besides learning about the role of CO2 on driving safety, this project also aimed to provide recommendations to Senseair (partner in the project) on the calibration of future in-vehicle CO2 sensors. To address these objectives, a study was designed to be conducted on the VTI simulator in Linköping (Sweden). The simulator was placed inside a 24m3 tent specially built for this project in order to manipulate and regulate the indoor CO2 levels. This was done by means of a system that allowed pure CO2 mixed with fresh air to be injected into the appropriate concentrations. The indoor CO2 level was automatically regulated through sensors and a closed-control system.]]></description>
      <pubDate>Fri, 02 Dec 2022 11:41:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2075225</guid>
    </item>
    <item>
      <title>Sonic interaction in intelligent cars</title>
      <link>https://trid.trb.org/View/1948939</link>
      <description><![CDATA[Highly automated cars (Level 4 or 5) allow their users to become passengers instead of drivers and this means that the interaction between the car and their users will change. This opens up possibilities of creating new, innovative ways of interaction that could help, guide and support car users in their new role. The SIIC project has investigated if and how sound can be used for user interaction in highly automated cars. Our general hypotheses have been that sound-based interaction, “auditory displays'', can fulfil a number of purposes identified as crucial for the user experience in highly automated cars; it can increase trust, reduce motion sickness, enhance users’ mental model of the automation and enhance their general comfort and wellbeing. Our main approach has been to design auditory displays based on a continuous sonification approach that is more proactive and subtle in comparison to the traditional chimes used in cars today. Furthermore, it has also been the aim to merge ideas from the computer game industry with research and methods from the car industry to be able to innovate this novel research area.]]></description>
      <pubDate>Fri, 06 May 2022 17:08:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948939</guid>
    </item>
    <item>
      <title>Entwicklung eines vereinfachten Verfahrens zum Test der Toxizität und Rauchentwicklung beim Brand von in Kraftomnibussen verbauten Innenraummaterialien </title>
      <link>https://trid.trb.org/View/1646740</link>
      <description><![CDATA[Für die Anwendung im Busbereich soll im Rahmen des Projekts ein vereinfachtes Verfahren zur Ermittlung der Toxizität von Rauchgasen entwickelt werden. Es ist zu klären, ob das Verfahren nur die überwiegend verbauten Materialien (beispielsweise von Decke, Wand, Boden und Sitzen) berücksichtigen muss sowie ob und wie man die für die Toxizität essentiellen Gaskomponenten berücksichtigen kann. Das entwickelte Verfahren soll in die Diskussionen internationaler Vorschriften auf UNECE-Ebene eingebracht werden. ABSTRACT IN ENGLISH: A simplified method for determining the toxicity of smoke gases for use in the bus sector is to be developed within the framework of the project. It has to be clarified whether the process only has to consider the predominantly used materials (e.g. ceiling, wall, floor and seats) and whether and how the toxic smoke gas components can be considered. The procedure developed is to be introduced into the discussions of international regulations at UNECE level.]]></description>
      <pubDate>Wed, 28 Aug 2019 03:10:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1646740</guid>
    </item>
    <item>
      <title>Investigation of NVH phenomena at electric vehicles</title>
      <link>https://trid.trb.org/View/1605928</link>
      <description><![CDATA[Sound quality is one of the key interfaces customers evaluate with their vehicles. New powertrain concepts, either fully electric or hybrid, come with new NVH problems and previously unknown phenomena. The entirely different setup of electric engine and gearbox and the higher rotational speeds are now creating perceivable noises and vibrations at way higher frequencies. Further, the omission of both combustion engine and exhaust system eliminates two of the most dominant sound sources. These systems were typically masking many other sounds, which are now perceivable. Considering the whole vehicle, measurement points and used transducers can remain the same, even though the sound field itself is rather different. While exterior noise is rather exciting due to the regulatory point of view, rotational analysis is still an exciting topic and needs to be further investigated.]]></description>
      <pubDate>Thu, 25 Jul 2019 10:04:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1605928</guid>
    </item>
    <item>
      <title>Voice recognition and in-car communication. Testing procedures and performance parameters</title>
      <link>https://trid.trb.org/View/1605927</link>
      <description><![CDATA[In-car Communication (ICC) and voice-controlled operation are important factors when it comes to improving comfort in vehicles. Already today, modern vehicles are equipped with voice recognition. Carmakers are increasingly interested in the integration of ICC; the first cars with integrated ICC are available. Only high performance of such systems will improve comfort in vehicles and reduce driver distraction. The articles gives an overview on the set-up, the testing procedures and the performance parameters requested to guarantee the desired functionality and meet today’s high demands for audio and voice quality.]]></description>
      <pubDate>Thu, 25 Jul 2019 10:04:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1605927</guid>
    </item>
    <item>
      <title>Battery electric vehicles. What is the future of the NVH package?</title>
      <link>https://trid.trb.org/View/1605623</link>
      <description><![CDATA[In this article, the current NVH (Noise Vibration Harshness) performance in the interior passenger compartment of Battery Electric Vehicles (BEVs) is compared with their Internal Combustion Engine (ICE) counterparts.  Electric powertrains can potentially bring some remarkable changes for vehicle Noise, Vibration and Harshness (NVH) due to noise from battery cooling and powertrain whine among others, in addition to tire and aerodynamic noise becoming more prominent in the absence of a standard Internal Combustion Engine (ICE). To investigate the NVH performance, experimental tests are carried out in two different configurations: besides interior Sound Pressure Level (SPL) measurements in operational conditions on the road under Wide Open Throttle (WOT) acceleration and constant speeds of 50, 80 and 120 km/h, reciprocal transfer function measurements in a semi-anechoic room have also been carried out. In light of the test results and the main global automotive market trends for electric vehicles, it looks reasonable to foresee that the NVH package of BEVs is certainly not going to become redundant anytime soon. Electric vehicles have to face many of the NVH issues that conventional ICE vehicles have faced until today. Tire and aerodynamic noise is equally present for any kind of powertrain, while ancillaries (e.g. air conditioning compressor, brake booster vacuum pump) and running components (e.g. battery and electrical motor cooling systems) devoted to electric powertrains will make additional noise. In addition, the electric motor, although generally quieter than ICE, can still emit remarkable high frequency noise. In general, vehicles need to become quieter, lighter and more energy-efficient, no matter the type of propulsion. As a consequence, new types of drives such as electric cars do require lightweight NVH components that integrate acoustic and aerodynamic functions. Electric vehicles also open innovative application areas for the treatment and insulation of bothersome high frequency noise from the electric motor, as well as road and wind noise. This is particularly true considering that there is also a growing demand from motorists for a significantly increased driving comfort for future vehicles. (A)]]></description>
      <pubDate>Thu, 25 Jul 2019 10:04:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1605623</guid>
    </item>
    <item>
      <title>How is driving related attention in driving with visual secondary tasks controlled?: Evidence for top-down attentional control</title>
      <link>https://trid.trb.org/View/1506367</link>
      <description><![CDATA[It is assumed that in driving with visual secondary task, attention is mainly controlled through top-down processes. They direct attention to previously selected, driving relevant parts of the environment. In a driving simulator study, the phenomenon of change blindness is used as a method to asses the focus of attention. In drives with defined and controlled situational circumstances, the hypothesis is studied that in driving with visual secondary tasks, drivers direct their driving related attention primarily to parts of the scene that are relevant for driving. The participants repeatedly approached intersections. During the approaches, a gaze pattern typical for driving with a visual secondary task was experimentally created through occlusion. Change blindness was measured for driving relevant as well as driving irrelevant vehicles. Results for N=16 subjects showed influence of relevance on the amount of change blindness.]]></description>
      <pubDate>Wed, 28 Mar 2018 10:21:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1506367</guid>
    </item>
    <item>
      <title>Intrusiveness of a visual detection task on secondary and driving task performance</title>
      <link>https://trid.trb.org/View/1506366</link>
      <description><![CDATA[A driving simulator study was conducted to investigate the intrusiveness of the visual detection task (VDT) on driving and secondary task performance. A within-subject design was used to assess both objective and subjective data in 16 participants. In terms of objective measures, the results indicate that the VDT has a significant effect on secondary task performance, with increased task completion time, and a non-significant effect on driving related measures. Participants perceived a higher level of time pressure, mental load and stress when using the VDT. Hence, the study showed that the VDT was intrusive while performing secondary tasks, based on both objective and subjective data.]]></description>
      <pubDate>Wed, 28 Mar 2018 10:21:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1506366</guid>
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