<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>Simulation and emulation of water spray for validation of optical sensors (SEVVOS)</title>
      <link>https://trid.trb.org/View/2598586</link>
      <description><![CDATA[This research investigated visibility degradation caused by vehicle-generated water spray on wet surfaces, using experimental tests, simulations, and data analysis to examine spray dynamics and their effects on camera and sensor performance. Dynamic tests faced challenges with automated contrast analysis due to insufficient resolution, lack of camera calibration, and poor lighting. Targets were too small in images, and low contrast, even without spray, prevented reliable detection. Similar issues affected static tests, although higher light levels enabled more consistent results. High-beam headlights worsened contrast degradation by illuminating spray particles. These findings emphasized the importance of proper calibration, resolution, and lighting for accurate data collection. Outdoor tests on AstaZero test tracks showed that water depth and vehicle speed significantly influence spray and visibility.]]></description>
      <pubDate>Fri, 12 Sep 2025 10:18:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2598586</guid>
    </item>
    <item>
      <title>Sensor testing in adverse visibility conditions (SUS) : Final report</title>
      <link>https://trid.trb.org/View/2491187</link>
      <description><![CDATA[Reduced visibility from bad weather conditions such as fog, rain, snow, and water spray on wet roads, presents a significant challenge for active safety (ADAS) and autonomous driving (AD) systems. To accurately perceive its surroundings these AD and ADAS systems use sensors such as camera, radar, and lidar but these sensors are sensitive to interference from adverse weather conditions. To ensure the reliability and safety of ADAS and AD systems in all weather conditions, it is important to test these systems in reduced visibility conditions. Water spray generated by passing cars on wet road surfaces impairs the driver's ability to detect other vehicles, road signs and other critical information. However, testing these conditions can be challenging, as it is difficult to recreate the same level of spray and visibility in controlled laboratory conditions. The purpose of this project is to develop a repeatable and controlled method for testing the performance of sensors for ADAS and AD systems under reduced visibility from water spray on wet roads. The project aims to further investigate the key challenges posed by reduced visibility and identify the most effective methods for recreating the same level of visibility degradation in controlled conditions.]]></description>
      <pubDate>Fri, 17 Jan 2025 15:16:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2491187</guid>
    </item>
    <item>
      <title>Test av åretruntdäck : väggrepp på is och snö samt barmark</title>
      <link>https://trid.trb.org/View/2389007</link>
      <description><![CDATA[All-season tyres have previously not been approved for use as winter tyres in Sweden but are now allowed after a change of regulations in 2019. To compare the grip of this type of tyre with regular winter and summer tires, brake tests were conducted for 14 different all-season tyres on packed snow and ice, as well as on dry and wet asphalt. The tyres were selected to be representative of the available all-season tyres on the Swedish market. The results show large differences in braking grip between different all-season tires. Some tyres perform more like European non-studded winter tyres, and others more like summer tyres, which seems to be a conscious choice by the various manufacturers. On average, the braking distance of all-season tyres on snow is clearly longer than that of both Nordic and European non-studded winter tyres, and although there are all-season tyres that are similar to European winter tyres on snow, others perform significantly worse. On ice, the braking grip of all-season tyres is much worse compared to the Nordic non-studded reference tyre. Our assessment is that the ice grip is generally too poor to constitute a safe alternative on Swedish winter roads, and that one of the winter-approved all-season tyres performed just as bad as one of the summer tyres on ice is remarkable. There is a correlation between low rolling resistance and poor ice grip, which indicates that measures to reduce rolling resistance can have a negative impact on the ice grip of this type of tyre. Braking performance on dry and wet asphalt for all-season tyres are widespread, with the best all-season tyres performing equally with summer tyres, and the worst being about the same level as the best of the Nordic winter tyres. We can therefore not recommend all-season tyres as an alternative to winter and summer tyres.]]></description>
      <pubDate>Mon, 10 Jun 2024 14:05:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2389007</guid>
    </item>
    <item>
      <title>Utvärdering av olika typer av profilering och nedfräsning av vägmarkering : kant- och mittlinjer på länsväg 250</title>
      <link>https://trid.trb.org/View/2145749</link>
      <description><![CDATA[To achieve visibility in wet conditions for longitudinal road markings, several types of profiled markings are used in Sweden. Guidelines for which type of profile should be used on state roads are lacking.  The aim of this study is to increase knowledge of profiled road markings, with respect to functionality and durability. Especially, comparisons should be made between stairs and drops with 60% coverage for intermittent edge lines, between milled and non-milled edge lines, and between centre lines in rumble strips with a sinusoidal pattern, either milled or non-milled.  To achieve the aim a part of a county road has been used, where new road markings were applied in 2019. The edge line was either designed as stairs or drops and was occasionally milled, while the centre line was designed as either stairs or drops and was in different types of sinusoidal-patterned rumble strip. Hand-held measurements of dry and wet retroreflectivity, as well as luminance coefficient, were conducted and followed up over the years 2020–2022 at certain measurement points. Additionally, mobile measurements over the road have been done, road marking function after a simulated heavy rainfall has been examined, and road marking durability and visibility was also assessed visually. The study was supplemented by a minor literature compilation focusing on studies from the Nordic countries.]]></description>
      <pubDate>Mon, 03 Apr 2023 16:47:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2145749</guid>
    </item>
    <item>
      <title>The effect of water and snow on the road surface on rolling resistance</title>
      <link>https://trid.trb.org/View/1894935</link>
      <description><![CDATA[Rolling resistance is due to the interaction between road surface and tires and forms part of the driving resistance that a vehicle needs to overcome to move forward. Those of the road surface properties that are seen as most important for rolling resistance are macro texture and unevenness along the road. But water and snow on the road surface also contribute to the rolling resistance. Precipitation that remains on the road means that the wheels need to be driven through and displace water or snow, and this leads to increased resistance. In addition, water cools more efficiently than air, which has an effect on the behavior of the tires as their viscoelastic properties are temperature dependent. The tires work at a lower temperature in the presence of precipitation, which in itself increases the resistance.  Speed, temperature and water depth are the explanatory variables often found in the literature to describe the effect on rolling resistance due to water on the road surface. It has been shown that rolling resistance increases with increasing speed, increasing water depth and decreasing tire temperature. The results indicate that the effect can be significant, with measurements showing an increase of 30 to 40 percent of the rolling resistance coefficient depending on the speed and thickness of the water film. However, the literature in the area is relatively limited, and the reason for this is probably linked to the difficulties that exist in measuring and modeling the rolling resistance effect in water. These difficulties are due to, among other things, measuring the depth of the water film and the temperature of the tires and that the temperature of the tires needs to be stable during measurements.  Studying the impact of snow on rolling resistance also involves some difficulties in that there are many different types of snow with varying properties and behavior during deformation. Data available is also limited and the relationships are not sufficiently developed so that they can be fully used to describe the behavior of the snow with respect to deformation and load. The complexity of the impact of snow on rolling resistance means that a combination of theoretical calculations and field studies is needed to determine the values of the components included. However, some studies have been carried out that aim to explain the impact of snow, both theoretical and via field measurements. The explanatory variables often used are snow depth, snow density and tire contact surface with road surface. In general, the results show that snow has a large effect on the resistance and that it should therefore be considered, especially in areas where snow remains on the ground for a long time.]]></description>
      <pubDate>Wed, 01 Dec 2021 14:47:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1894935</guid>
    </item>
    <item>
      <title>Using Pavement Texture to Screen and Target Annual Skid Number Assessment</title>
      <link>https://trid.trb.org/View/1632784</link>
      <description><![CDATA[The purpose of this study is to develop an understanding of how pavement texture data can be used to inform roadway safety and develop a more targeted approach to Skid Number (SN) assessment with focus on high risk areas. Pavement texture data is a new data source for the Utah Department of Transportation (UDOT). Skid data and pavement texture data from 2017 were compared for a large, statewide dataset. Statistical analysis indicates there is not a strong correlation for SN and texture depth. Pavement texture, however, was found to be sensitive to surface type and some surface types represent a stronger correlation than others. Screening thresholds were developed for texture depth to help screen and refine skid data collection efforts for chip seal pavements. Cost saving estimates from using the screening thresholds for a case study result tens of thousands of dollars per year, however, given the duplication of screened out routes to reach areas to measure, the cost savings could be less. Texture thresholds were evaluated to target areas for skid data collection at more frequent intervals for stone matrix asphalt (SMA) pavements. Due to the weak skid data and texture data correlation, this method would still result in a portion of areas targeted for measurement that already have a good SN. A comparison of wet pavement crash history to pavement texture did not yield a strong correlation.]]></description>
      <pubDate>Tue, 16 Jul 2019 16:32:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1632784</guid>
    </item>
    <item>
      <title>Contribution to pavement friction modelling: an introduction of the wetting effect</title>
      <link>https://trid.trb.org/View/1626913</link>
      <description><![CDATA[This paper presents a friction model describing the tyre rubber/road interaction that takes into account the viscoelasticity of the tyre rubber, the texture of the road surface and a water layer between the tyre/road interface by introducing explicitly a computation of the water layer effect in the calculation process of the hysteretic friction. The geometry of the wetted portion of the interface model is simplified by transforming it into an equivalent hydrodynamic bearing. Utilising the Reynolds equation, the bearing load capacity is calculated and the resulting forces are subtracted from the contact load when calculating the forces of the hysteretic friction. The mechanical behaviour of the rubber is represented in the model by Kelvin–Voigt model. The frictional forces due to hysteresis are calculated at any given operating conditions (load, slip speed, etc.) from the contact geometry of rough surfaces caused by the viscoelastic behaviour of rubber. To validate the model, a set of surfaces including real pavements and artificially textured slabs were selected covering a wide range of microtexture and macrotexture combinations and the computed and measured friction compared. To describe the contact geometry of rough surfaces using macrotexture and to measure actual friction, the Circular Track Meter and the Dynamic Friction Tester devices were used, respectively. The friction coefficients computed using the model were compared to the measured friction coefficients. The obtained results are presented in the paper and proved to provide high correlation between the measured and modelled friction. The model is capable to predict wet friction at low as well as high speeds on wet surfaces, thus proving to be capable to take adequately the wetting effect on the variation of friction with increasing speed. Recommendations are provided to improve the model and extend it to a tyre friction model.]]></description>
      <pubDate>Wed, 05 Jun 2019 12:53:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1626913</guid>
    </item>
    <item>
      <title>Evaluation of Vehicle Braking Performance on Wet Pavement Surface using an Integrated Tire-Vehicle Modeling Approach</title>
      <link>https://trid.trb.org/View/1582004</link>
      <description><![CDATA[Water film on a pavement surface greatly increases vehicle accident rates on rainy days. The simple use of a lower friction coefficient to evaluate the vehicle braking performance oversimplifies the contact mechanism between the tire and the pavement, and the use of a pure single tire model simulating hydroplaning was not able to reflect actual vehicle braking-cornering behaviors. This paper proposes an integrated tire-vehicle model to evaluate vehicle braking performance based on Persson’s friction theory, a tire hydroplaning finite element model, and a vehicle dynamic analysis. The friction coefficients between the tire and the pavement were calculated theoretically from the pavement surface morphology and the tire rubber properties; the tire hydrodynamic forces were obtained mechanistically from the hydroplaning model with different water film thicknesses and were used as inputs for calculating the braking distances in a vehicle model. The calculated friction coefficients and braking distances were verified using the field test results. A case study was conducted to illustrate the approach and evaluate the vehicle braking performance on straight and curved road sections. The results show that both longitudinal braking distances and lateral slip distances should be considered in the evaluation of vehicle braking performance.]]></description>
      <pubDate>Mon, 04 Mar 2019 09:42:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1582004</guid>
    </item>
    <item>
      <title>A Correlation Between Braking Tire Contact Friction Energy and Pavement Skid Deterioration</title>
      <link>https://trid.trb.org/View/1572289</link>
      <description><![CDATA[Wet skid-resistance is of paramount importance for road safety as it has been recognized to affect wet-road accidents. Pavement skid resistance is primarily a function of the surface texture (both micro-texture and macro-texture) which deteriorates during the pavement life. It is a known fact to road asset managers, that short and long term planning and prioritizing of periodic maintenance and rehabilitation programs require the use of accurate deterioration models. Many researchers developed methods to predict the evolution of asphalt pavement skid resistance based on aggregate texture before and after polishing, gradation of asphalt mixture, and traffic levels, but very few studies investigated the impact of type and travel mode of traffic vehicles. In this paper, a relationship between experimentally measured contact friction energy and pavement wear is derived for a specific bituminous surface course. Test equipment and methods for measurements of variable slip skid resistance on outdoor surface courses are described and employed to perform a full-scale accelerated pavement wear test. A reasonable correlation is derived between cumulated frictional dissipated energy in the tire footprint area and deterioration of pavement skid resistance and texture. Preliminary results seem encouraging and it is believed that a refined description of the effect of traffic may help in improving accuracy of skid resistance generalized deterioration models.]]></description>
      <pubDate>Sat, 02 Mar 2019 15:41:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1572289</guid>
    </item>
    <item>
      <title>Simulation of Impact of Water-Film Spray on Visibility</title>
      <link>https://trid.trb.org/View/1563407</link>
      <description><![CDATA[On rainy days, large rain particles in the air block and scatter the light so that visibility on roads decreases. However, it is conventionally ignored that the spray caused by high-speed vehicles with the existence of water film on pavement also creates visibility issues. In this study, a model to calculate the spray concentration was established. Monte Carlo simulations were performed to characterize the stochastic process of the weakening light-transmission phenomenon due to spray. Combining Mie scattering theory and the definition of visibility in meteorology, the visibility reduction due to the spray created by water film at different vehicle speeds was quantified. Simulation results indicated that the effect of spray on visibility is approximate to that of heavy rain when the water-film depth is 5 mm. The visibility generally decreases with the increase of vehicle speed and water-film depth. However the former has greater influence on visibility compared with the latter. To ensure visibility at water-film depths of 5, 2.5, 1, and 0.5 mm, speeds should be controlled below 93, 96, 101, and 106  km/h, respectively. The developed model can be useful in understanding and estimating the influence of spray on visibility and help formulate a low-visibility warning strategy.]]></description>
      <pubDate>Thu, 20 Dec 2018 15:33:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1563407</guid>
    </item>
    <item>
      <title>Vinterdäck till cykel: ett jämförande test</title>
      <link>https://trid.trb.org/View/1573786</link>
      <description><![CDATA[The purpose of this study has been to compare the winter road grip of various bicycle tyres, as well as a pair of unstudded winter tyres, through cycling tests. In addition to grip, other characteristics that could be important to a cyclist, such as rolling resistance and wear resistance, were also tested. The tyre’s grip on ice was tested by brake tests and manoeuvring tests indoors in an ice hockey rink. Four different test drivers were used to capture differences in driver behaviour, as well as to get a variation in the cyclist’s weight. The tyre rolling resistance was measured by indoor coast-down tests. Finally, the grip was tested on dry and wet asphalt by outdoor brake tests. Between the various tests, the studded tyres were examined with regard to the number of lost studs. In total, seven different studded tyres, two unstudded winter tyres and a summer tyre were tested. The brake tests on dry and wet asphalt could not show any difference in performance between the different tyres. The winter tyres, studded as well as unstudded, had as good grip on asphalt as the tested summer tyre. In the case of ice grip, the two tyres with the highest number of studs, 240, were clearly superior to the others. The rolling resistance tests showed differences between the different tyres and it is not the number of studs but rather the rubber properties and the puncture protection that has the greatest impact on the rolling resistance. The wear tests indicated that some of the tested models may be particularly prone to losing studs, but as the tests included only two samples of each tyre model, it is not possible to draw certain conclusions regarding wear resistance.]]></description>
      <pubDate>Wed, 12 Dec 2018 10:46:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1573786</guid>
    </item>
    <item>
      <title>Effekten på rullmotstånd av vatten och snö på vägytan</title>
      <link>https://trid.trb.org/View/1573759</link>
      <description><![CDATA[Rolling resistance depends on the interaction between road surface and tire and forms part of the driving resistance a vehicle needs to overcome to move forward. The road surface properties considered the most important for rolling resistance are macro textures and unevenness along the way. But water and snow on the road surface will also affect the rolling resistance. Precipitation remaining on the road surface means the wheels need to be driven through and move water or snow, which gives increased resistance. The purpose of the report is to provide an overview of the state of knowledge about how the rolling resistance is affected by water and snow on the road surface. Literature has been sought in databases of scientific articles and reports, and also on the internet. A review has been made of about 50 reports and articles published from the 1970s to 2018. The overview shows that water and snow on the road surface can have a significant effect on the rolling resistance. For water on the road surface, speed, temperature and water depth are often used as explanatory variables. To describe the snows impact on the rolling resistance, the explanation variables use snow depth, snow density, tire contact surface with the ground. An uncertainty in the results of the studies reported is that several have been implemented in the 70's and 80's. Since then, measuring methods as well as measuring equipment have been developed and improved. The tire properties have also improved, which has had an effect on the rolling resistance. Therefore, to obtain snow and water rolling resistance measurement data for tires and vehicles used on normal roads today, new measurements should be made using the most recent measurement methods and measurement equipment. This would reduce the uncertainty in measurement results and provide current information that can be used to update the relationship between fuel consumption and water and snow on the road surface.]]></description>
      <pubDate>Wed, 12 Dec 2018 10:45:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1573759</guid>
    </item>
    <item>
      <title>Empirical Model for Predicting the Resilient Modulus of Frozen Unbound Road Materials Using a Hyperbolic Function</title>
      <link>https://trid.trb.org/View/1552848</link>
      <description><![CDATA[The resilient modulus (MR) is a key parameter required in the mechanistic-empirical methods, which are widely used for the rational design of pavement structures. However, experimental determination of the MR is expensive and time-consuming since it requires elaborate equipment for testing and trained personnel. Due to this reason, several researchers have proposed models for predicting the MR of unbound road materials that take into account the influence of wetting and drying conditions. However, the presently available models in the literature have some limitations for the prediction of the MR of these materials at a frozen state. In this paper, a model with two-constants is proposed for predicting the variation of the MR with subzero temperature for unbound road materials exploiting the hyperbolic shape of the frozen resilient modulus - subzero temperature relationship. Experimental data on eighteen different unbound road materials including both fine- and coarse-grained soils, and under both saturated and unsaturated conditions, were used to validate the proposed model. It is shown that the proposed model can reasonably well-predict the MR of the investigated soils that are in a state of frozen condition. More investigations on different types of soils would be useful for better understanding the strengths and limitations of the proposed model. In addition, the effect of stress should be incorporated for further improving the model.]]></description>
      <pubDate>Mon, 22 Oct 2018 09:29:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1552848</guid>
    </item>
    <item>
      <title>Quantifying the safety effects of pavement friction improvements – results from a large-scale study</title>
      <link>https://trid.trb.org/View/1493703</link>
      <description><![CDATA[It is fairly well understood that there is link between pavement friction and safety, or more specifically, the probability of wet-weather skidding crashes. However, robust knowledge on the comparative quantitative effects on safety for specific treatments that improve pavement friction, which can assist pavement engineers in economically justifying and prioritising treatments, is sparse. The large-scale study on which this paper is based aimed to firm up this knowledge for a variety of low-cost treatments and road classes, using state-of-the-art methodology and substantial, high-quality data-sets. This was a retrospective study for pavement safety performance, looking back at crash data before and after treatments were implemented. Both flexible and rigid pavement treatments were analysed and crash modification factors were estimated for several target crash types and road classes. The majority of the friction improvement treatments considered under this effort are typically used for pavement preservation or minor rehabilitation purposes. Although pavement engineers recognise that these treatments generally improve safety, they are not typically installed by highway agencies explicitly for safety improvement objectives. The combined results for most treatment types confirmed nevertheless the safety benefits for wet-road crashes, with a few exceptions. For dry road crashes, there was some evidence of the deleterious effects of speed adaptation to new surfaces in that crashes increased for a few treatments on some road types.]]></description>
      <pubDate>Sun, 14 Jan 2018 17:58:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1493703</guid>
    </item>
    <item>
      <title>Experimental investigation on skid resistance of asphalt pavement under various slippery conditions</title>
      <link>https://trid.trb.org/View/1464039</link>
      <description><![CDATA[The skid resistant performance of slippery pavement is one of the most important pavement surface characteristics, as it is associated with both pavement serviceability and traffic safety. Through simulating different pavement conditions in the freezing laboratory, skid resistance of asphalt pavement under various slippery conditions is measured with pendulum friction coefficient tester. Then, the effects of pavement temperature on skid resistance of dry, wet, icing and snowy pavements are quantitatively analysed. Furthermore, factors exerting effects on test results are taken into account, such as thicknesses of ice and water film on pavement. Through quantitative analysis, empirical evaluation model of pavement friction coefficient (PFC) under different conditions is established. To facilitate practical engineering application, reference standard values of PFC are recommended. Finally, the PFC is classified into seven levels, which illustrates the corresponding relationships of friction rank, skid resistance assessment, PFC range and pavement conditions.]]></description>
      <pubDate>Wed, 10 May 2017 13:06:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1464039</guid>
    </item>
  </channel>
</rss>