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- 3D Pavement Surface Macrotexture: Measurements And Friction RelationshipsShalaby, Ahmed; El Gendy, Amin (2012)Pavement macrotexture is typically reported as mean profile depth over a standard base length. Recently, a new measurement method based on photometric stereo system was introduced. The method requires a minimum of three images of the surface that are illuminated from different directions and isolated from ambient lighting. The variation in intensity of the lighting is used to recover the 3D pavement surface. This paper discusses applications of the photometric stereo system as a new non-contact texture measurement method. The 3D pavement surface is analyzed in space and frequency domains. In frequency domain, the power spectrum energy which reflects the wavelength content of the surface model is introduced as an indicator of surface evenness. The relationship between friction and the 3D texture indicators is examined. The research shows that the texture indicators computed from the recovered surface provide new substantial information on the quality and condition of the riding surface.
- About The Reproducibility Of Texture Profiles And The Problem Of SpikesGoubert, Luc; Bergiers, Anneleen (2012)The ISO working group ISO/TC43/SC1/WG39 has recently been worrying about the quality of texture profiles, measured with laser profilometers. It appears that the quality has not improved in recent years, rather on the contrary: in spite of the technological progress it appears to decrease! The WG is especially concerned of the presence of invalid positive spikes in some profiles which might dramatically affect the Mean Profile Depths (MPD) [1] and to some extent the texture spectra calculated with those spectra, if one does not properly deal with these erroneous measurement points prior to calculating the MPD or spectrum. In this paper the results of an international round robin test with static laser profilometer devices on two epoxy moulds of dense asphalt concrete road surfaces are shown, indicating the reproducibility of this kind of devices for the wavelength range from 2,5 mm up to 125 mm. A new procedure to deal with the spike problem is presented. The aim is to remove the spikes without affecting significantly the valid part of the spectra. The effect on MPD and spectra will be shown for some typical cases. The method, based on the detection of steep jumps in the profile, appears to work.
- About The Rolling Resistance Trailer And Parameters Influencing Rolling ResistanceBergiers, Anneleen; Goubert, Luc; Vuye, Cedric (2012)The issue of global warming by an excessive amount of carbon dioxide (CO2) in the atmosphere is a hot topic and the consequences for man and environment become more and more clear. Road transportation plays a significant role in CO2 emission and unlike other sectors, its emission has even increased the last years. To stop this trend, different measures may be taken: e.g. tackling traffic congestion, lowering the consumption of the vehicles… Many other parameters influence CO2 emission by transportation: e.g. tyre, vehicle and road characteristics… In this paper the influence of the road surface is investigated with a “quarter-car” trailer, suitable to measure rolling resistance with a car tyre on different road surface types. Texture measurements with a laser profilometer are performed to examine the correlation between rolling resistance and texture. The impacts of different parameters are investigated: repeatability over short and long time, speed, wind, tyre inflation pressure, tyre load, tyre type … Some rough coast down measurements are performed to compare with the trailer method. By gaining more knowledge about this topic, more environmental friendly and sustainable road infrastructure may be developed and implemented. This is expected to be an important tool for policy makers in their fight against CO2 emission.
- Assessment Of Polishing Behaviour Of Sand Using The Test Device According To Wehner/SchulzeHofko, Bernhard; Kirchmaier, Lukas; Blab, Ronald; Mader, Matthias (2012)To ensure the safety of road users during driving maneuvers an adequate skid resistance level of the wearing courses is required. Skid resistance of dense road surface layers besides the texture profile also depends on the polishing resistance of both coarse and fine aggregates. In the European standards so far requirements concerning the polishing behaviour of mineral aggregates are given merely with regard to the PSV (Polished Stone Value), tested on stone chippings 8/11 mm. No specific specifications are set for the sand fraction 0/2 mm. This paper details a new Austrian evaluation background for the polishing resistance of sand using a Wehner/Schulze testing device of the latest design. It will be showed that the polishing resistance between coarse and fine aggregates differs, thus separate requirements for different particle sizes are necessary because only the combination of highly polishing resistant sand and gravel enables a sustainable skid resistance of road surface layers. Furthermore the reproducibility and the comparability of sand polishing values determined by an accuracy experiment will be presented. Within the accuracy experiment different parameters, which may affect the test result, were investigated. Based on the evaluation background and the results from the accuracy experiment requirements concerning the sand polishing resistance were set for highly stressed wearing courses in the Austrian standards. This new requirement for wearing courses will lead to a better durability in terms of skid resistance and therefore to reduced maintenance costs.
- Certification Process For Self-Wetting Continuous Friction Measuring Equipment Used For Construction And Maintenance Purposes On French AirportsGerthoffert, Jonathan (2012)Friction characteristics of runways are regularly measured to detect any change in skid resistance and to decide maintenance needs. Self-wetting continuous friction measuring equipments (CFME) are used for functional (construction and maintenance) measurements. Numerous friction measuring devices exist and are currently used on airports. These devices have different functioning principles: operating modes, water delivery systems, measuring tires types and pressures... It causes friction characteristics of runway to be both surface- and device-dependent. Many attempts have been made to correlate friction measuring devices with each other and good results have been achieved for functional friction measurements. Harmonization of friction measurements makes it possible to define minimum friction levels. Below these friction levels, corrective actions have to be taken to improve runway friction characteristics, and pilots have to be informed of such conditions. To achieve this, France has introduced a regulation to submit CFME to mandatory certification. This paper presents the certification process for self-wetting continuous friction measuring equipments used for functional measurements on French airports. Certification ensures aerodrome operators that CFME performs with reliability and consistency. It also harmonizes friction measurements between different devices and ensures a uniform acceptance of the minimum friction level. The certification process consists in correlation trials between the applicant device and the reference device, owned by the French Civil Aviation Technical Center (STAC). A special test track has been built on the grounds of Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR ex-LCPC). It has 11 differently textured test plots with surface properties covering a large range of friction levels. The performances of all applicant devices in terms of repeatability and consistency of friction measurements are checked. A device meeting the requirements for certification is then correlated to the STAC reference device and is issued with a certificate valid for two years. All self-wetting continuous friction measuring devices used for construction and maintenance purposes on French airports have to be certified. This process has proved to reduce significantly the variability of CFME friction results and progressively improved the overall consistency of applicant friction measurement devices. Examples of test results are presented and discussed in this paper.
- CPX Noise Measurements In Different Road SurfacesParra, Laura; Casas, Tomas; Álvarez de Sotomayor, Roberto; del Cerro, José; Castillo, Maria Esther (2012)One of the aims of Directive 2002/49/EC as stated in article 1 is to define a common approach intended to avoid, prevent or reduce the harmful effects due to exposure to environmental noise. Within this framework, the European Commission is working on the assessment of road traffic noise. The noise production of a vehicle is defined by the two main parameters - category, speed - and it also depends on several environmental or specific effects. One of them is the type of road surface, as it can lead to differences in sound levels up to 15 dB for the same traffic flow and composition. Therefore, it becomes of the highest importance to know the influence of the different road surfaces in the vehicle noise emission. At this moment, there is also an open debate within the EU whether to develop some kind of noise classification procedure for the different road surfaces or not. In relation to these subjects, CEDEX is working on the measurement of tyre-road noise with the CPX method in several road surfaces in the Spanish National Road Network. The CPX method, as stated in the ISO/CD11819-2, allows measuring the influence of surface characteristics on tyre-road noise.
- Determination Of Correlation Between Road Pavement Skid Resistance And Braking DecelerationKokot, Darko; Rijavec, Robert; Ambroz, Miha (2012)There are many situations when road pavement surface skid resistance drops to unacceptable levels. Skid resistance is an essential pavement property for road safety, but drivers are not able to assess its degree by visual means, although in the end they must be able to stop their vehicles safely within the stopping sight distance. In our research normalized braking deceleration was related to SCRIMTEX SFC values and analyzed for different driving conditions (wet/dry), vehicle systems, skid resistance levels, measuring speeds and nominal initial vehicle speeds when full braking. A relation can be used to calculate the stopping sight distance and maximum safe speed in different road conditions. In the case of below-average vehicle systems, relations of this kind can be used to determine, within some degree of uncertainty, the limit SFC values at which some traffic operations and management activities should be performed (e.g. speed limits can be reviewed and new traffic signs erected to support road users in safer driving). Applying such limit values to the national regulations means that they can be directly interpreted from the traffic safety perspective.
- Determination Of Pavement Surface Cracks From Video-Images Using An Image Scale-Space ApproachArmenakis, C.; Ningyuan, Li (2012)Assessment of pavement surface distress is an important component of the pavement management process. Pavement surface distresses characterize failures and distortions of the pavement surface structure. A large number of highway surface images have been collected through the application of a video image system. We present an automated approach that detects pavement surface cracks from a forward viewing video camera system. Initially the oblique imagery is transformed to a rectified one which supports quantitative measurements of the crack patterns. For the detection and extraction of pavement surface distress elements, we propose to use a scale-space image approach, where the image scale is defined based on the level of detail of the image structure to be detected. Finally, the detection of crack patterns is performed considering the image as a 3D intensity surface where the bright and dark lines are considered as ridges and valleys. The approach is based on determining the local directions of the image curvature along the curvilinear lines, and determining where along these directional profiles the second derivative of the line profile reaches its maximum absolute value.
- Development Of A Pavement Condition Assessment Method For The Interstate Highway SystemSimpson, Amy; Groeger, Jonathan; Rada, Gonzalo R.; Guerre, Joseph (2012)As part of a project conducted by the United States Department of Transportation (US DOT) Federal Highway Administration (FHWA), methods are being developed to assess infrastructure condition and health with a focus on pavements on the Interstate Highway System. The project scope includes development of prototype tools to provide FHWA and State DOTs ready access to key information on pavement and bridge performance based on these methods for assessing condition and health. These tools are designed to allow a better and more complete view of infrastructure health nationally and form the foundation for a performance management system for the US highway system. In support of this goal, a pilot study was conducted on a three-state corridor to investigate and compare methods for assessing pavement condition and, subsequently, health. As part of the pilot, three sets of data were compiled, processed, and compared: National (Highway Performance Monitoring System), State (primarily State Pavement Management System data and supporting information), and field data collection using an automated multi-function vehicle. This paper explores the results on the approach for categorizing pavement condition as Good/Fair/Poor. A summary of the findings are presented along with recommendations for future activities necessary to develop a pavement condition performance indicator.
- Development of a Prediction Model for Splash and SprayFlintsch, Gerardo W.; Viner, Helen; Coyle, Fiona; Nesnas, Kamal; Hargreaves, David; Parry, Tony (2012)Under some conditions splash and spray create a significant nuisance to road users and some evidence suggests that they contribute to a small but measurable proportion of accidents. This paper reports on the development of a prediction model for splash and spray. The work has been funded by the Federal Highway Administration in order to assist engineers in decisions concerning the type and priority of maintenance on the road network. Ultimately, this could deliver a range of benefits including increased user satisfaction with the network, reduced accidents and a reduction in the detrimental effect of pollutants being deposited on the road verges and street furniture. The approach taken has been, firstly, to develop a method for predicting the depth of water that builds up on the road surface, considering the rainfall rate, pavement geometry and surface type. Models obtained from the literature have been validated through measurements of water depth carried out in a flume, using a number of typical road surfaces. Secondly, computational fluid dynamics has been used to estimate the level of nuisance to road users of the various mechanisms of splash and spray generation.
- The Development Of Asphalt Surfacing PropertiesWoodward, David; Millar, Phillip; Friel, Shaun; Mitchell, Richard (2012)This paper considers how the development of asphalt surfacing properties can be predicted in the laboratory. The research has been prompted by the ideals of sustainability coupled with the practical issues being faced by many countries around the world of how to improve, better manage and maintain their highway network. The properties of different types of asphalt surfacing evolve in different ways with time in relation to interactions with factors such as trafficking and climatic conditions. The examples given illustrate a range of methods that help understand these interactions and offer better prediction of likely in-service performance.
- Early Life And In Service Friction Characteristics Of Runway SurfaceWidyatmoko, Daru; Fergusson, Carl (2012)This paper presents friction data gathered from seven regional and major international airports in the UK, covering different surface courses, from the time of installation to in service. The wet friction monitoring at these airports was carried out by using Continuous Friction Measurement Equipments (CFME) over 4 years in service. Some materials showed reduction in the wet friction values during a few days after installation but then followed by a steady increase in the values, even without traffic; this demonstrated the importance of having a good mixture design and binder selection to ensure the early life friction remains above the specified minimum friction level. Longer temporary total ungrooved runway lengths have been successfully adopted at several UK airports where the authors were involved in the resurfacing work, without any issue associated with the early-life surface friction; this resulted in early completion, reduced airfield down time and cost saving. Records to date, demonstrating the ability of well designed surfacing material to maintain very good friction characteristics since the opening of the runways, are also presented.
- Electric versus Gasoline Vehicle Particulate Matter and Greenhouse Gas Emissions: Large-scale AnalysisRakha, Hesham A.; Farag, Mohamed; Foroutan, Hosein (2024-07-31)This study addresses the contentious issue of non-exhaust particulate matter (PM) emissions from battery electric vehicles (BEVs) compared to internal combustion engine vehicles (ICEVs) by developing models to quantify tire and brake PM emissions and incorporate them in a microscopic traffic simulation environment. Furthermore, exhaust greenhouse gas (GHG) emissions are quantified to develop a comprehensive picture of vehicle network emissions. The key findings are: 1) BEVs emit more tire and less brake PM emissions, thus necessitating a comprehensive analysis to avoid erroneous conclusions. 2) If at least 15% of travel is city driving, BEVs produce less non-exhaust PM emissions. 3) For the freeway section analyzed, a volume-to-capacity ratio of at least 0.25 is required for BEVs to produce less non-exhaust PM emissions. By incorporating these detailed models into traffic simulations, the study provides a tool for policymakers to better understand and manage vehicle emissions at a city level.
- Evaluation Of Longitudinal Evenness Of A Newly Constructed Road Section: A Detailed Study Of Different Evenness MeasurementsGeem, Van G.; Beaumesnil, B. (2012)The requirements for longitudinal evenness of newly constructed road surfaces in Belgium are expressed in the “Evenness Coefficient” (EC) defined as half of the surface between the profile as obtained from measurements with the “Analyseur de Profil en Long” (APL) and a curve representing the “ideal profile” calculated by a sliding average method. Requirements can be expressed in the gap height measured with the “three-metre straightedge” (TMS) but the acceptance of road works is often based on APL data. When requirements are not matched, the contractor must improve the longitudinal evenness after road works completion. Contractors and road administrations want to exploit APL data fully. This contribution discusses the finesses of longitudinal evenness measurements using APL, EC and TMS. A case study illustrates to what extend the APL data can be exploited. A road section with high unevenness was investigated by APL and TMS, and the geometrical unevenness of the road surface was measured point-wise by elevation measurements in the wheel paths on 8 sub-sections of the road. The case will confirm that a theoretical estimate of TMS gap height from APL data is realistic and will show rare influence of crossfall variation on the APL.
- Further Investigations On The Weighted Longitudinal ProfileSpielhoffer, Roland; Ueckermann, Andreas (2012)The weighted longitudinal profile (WLP) is a recent approach to characterize evenness of roads. This paper focuses on the development of an evaluation scheme for motorways derived from the power spectral density of the profile. When the evaluation scheme is established, the derived limits are verified. Different surface types (asphalt, concrete) and the influence of their typical evenness characteristic on the evaluation by the WLP are investigated. The WLP shows to be capable to clearly bring out these characteristics without introducing a bias into the evaluation. Motorway networks in Germany and Austria (data from first and second lane) are evaluated then. In comparison to the IRI (currently in use in Austria), the WLP shows a lot more differentiation between good and bad sections. A comparison of WLP and the planograph in the frame of new work approval of motorway sections in Austria is drawn, but further research is necessary to get a conclusive picture of a possible change in the new work approval regulations. Furthermore, the Austrian motorway ramps and intersections are evaluated. An adaptation of the evaluation scheme is proposed to take into account the different driving speed on ramps and hence lower requirements regarding the evenness.
- Fusion Of High-Resolution Laser Profile And Lidar Measurements For Enhanced Condition AssessmentWright, Dean; Dhillon, N.; Wright, Alex; Christie, Colin (2012)Accurate data on pavement condition is essential for the maintenance and assessment of road assets. This is commonly obtained using downward-facing laser survey devices operated traffic-speed to provide detailed measurements of the pavement surface. Interest in the use of LIDAR technology to complement such surveys has increased with better accuracy and cost-effectiveness of commercially-available systems. The potential applications of LIDAR systems have been demonstrated by several groups. These mainly focus on its ability to measure assets other than the pavement, as LIDAR is generally not considered to have sufficient accuracy to measure the pavement shape itself. This work undertakes an initial investigation of how LIDAR could be used in pavement assessment by using LIDAR to combine high resolution measurements collected over multiple survey lanes into a single set of data. This commences with the generation of 3D point clouds from all the measurement systems, followed by alignment and combination. The final hybrid 3D data set describes the pavement surface at a level of detail typical of traffic speed condition surveys. Potential applications in the field of pavement surveying include the improved identification of locations likely to affect vehicle handling, and the detection of areas at risk from ponding.
- Identifying Fine Aggregates Prone to Polishing in PCC PavementsFowler, David W.; Rached, Marc M. (2012)Surface polishing in portland cement concrete (PCC) pavements leads to higher incidences of skid-related accidents on highways. This type of failure is often associated with the usage of softer fine aggregate such as limestone sands. To identify polish resistance aggregates, state agencies like TxDOT have adopted tests such as the acid insoluble residue test (AIR). Since calcium carbonate is soluble in acid, no carbonate sand passes the AIR test which has a minimum limit of 60% in Texas. This paper describes research that was done to evaluate the polish resistance of aggregates using a laboratory concrete performance test. Concrete slabs made with different fine aggregates were evaluated for skid using a circular track meter (CTM), a dynamic friction tester (DFT), and a three-wheel-polishing device (TWPD). To ensure that the values obtained at the laboratory related to field performance, test sections constructed with 100% limestone sand and blended sands were also evaluated. Results show that some of the aggregates that failed the AIR test performed as well as some of the siliceous fine aggregates that passed the AIR test. Other aggregate tests such as the micro-Deval have shown to relate more closely to the concrete performance tests performed under laboratory conditions.
- Improving Highway Safety Through Pavement Friction Management ProgramsSmith, Kelly L.; Larson, Roger M.; Flintsch, Gerardo W.; Sherwood, Jim (2012)In recent years, there has been a major increase in activities related to improving highway safety in the U.S. Much of the emphasis has been placed on driver behavior (e.g., addressing aggressive, distracted, and impaired driving and the neglected use of seat belts) and roadway design (e.g., geometrics, roadside, and traffic control features), and this has led to updated FHWA regulations and guidance regarding the Highway Safety Improvement Program and major research publications, such as the NCHRP 500-series reports (Guidance for Implementation of the AASHTO Strategic Highway Safety Plan) and the 2010 American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (first edition). A similar upswing in activities has taken place with regard to the safety of pavement surfaces. Following efforts in the mid-1990s to comprehensively examine pavement surface characteristics (PSCs) (e.g., texture, friction, noise, hydroplaning potential), FHWA has developed policy guidance for Surface Texture for Asphalt and Concrete (Technical Advisory T5040.36) (2005), AASHTO has published the Guide for Pavement Friction (2008), and FHWA has developed policy guidance on Pavement Friction Management (Technical Advisory T5040.38) (2010). Building off these and other PSC-related technical advancements, and recognizing the need to apply pavement friction management (PFM) concepts and technologies in the U.S., the FHWA has sponsored a major, multi-year study to develop and demonstrate PFM programs at four state highway agencies (SHAs) using guidance contained in the AASHTO Guide for Pavement Friction. In Phase 1 of the two-phase study, a review of past efforts of quantifying the relationship between friction/texture and crashes was done, along with a review of both U.S. and International pavement safety programs/practices. In addition, a detailed evaluation of currently available friction/texture measurement equipment was performed to identify those best suited for the PFM programs to be developed in Phase 2 of the study. This paper discusses the examination of past studies investigating the friction/texture– crash relationship and the review of pavement safety programs/practices. It presents the main conclusions of these two research activities, as they relate to the planned development of PFM programs in four states (yet to be identified).
- Influence of Thin Waterfilm on Skid ResistanceBeautru, Yannick; Cerezo, Veronique; Do, Minh-Tan; Kane, Malal (2012)Most of past research on the skid resistance/road wetness relationship deal with thick water depths (> 1mm). Questions remain as to the variation of skid resistance with thin water films and the transition between the dry state and the so-called “damp” or “humid” state at which the skid resistance drop can be as high as 30-40%. This paper deals with a theoretical and experimental assessment of the friction/water depth relationship. The main objective is to estimate local water depths trapped between the tire and the road asperities and to define a so-called “critical” water depth which can be used for driver assistance systems. Tests are performed in laboratory and on test tracks. It was found that the friction-water depth curves have an inverse-S shape and present an initial constant-friction part before decreasing to a minimum value. A “critical” water depth, defined as the water depth above which the friction coefficient collapses significantly, is determined from observed friction-water depth curves. Influence of test speed and road surface texture on critical water depth is discussed.
- Lateral And Longitudinal Grip VariationWoodward, David; Millar, Phillip (2012)Longitudinal measurement of wet skid resistance is used in many countries to manage the safety of its highway asset. The effect of aggregate type/size, asphalt type / age, degree of trafficking, climate, corners, braking etc. can all be seen in the measured data. However, longitudinal measurement does not show differences in grip across the lane being measured. This paper first considers typical longitudinal variation and then looks at the effect of lateral variation. Simple examples are given for each. The combination of longitudinal and lateral variation is considered in the context of racing circuits. Three case studies explore how GPS based grip data can be plotted using GIS software. The case studies show how the vehicle/tyre interacts with the asphalt surface trying to seek equilibrium conditions.