7th Symposium on Pavement Surface Characteristics: SURF 2012
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The SURF 2012 symposium was held in Norfolk, VA from September 19 – 22, 2012.
The event was organized by the World Road Association in partnership with the American Association of State Highway and Transportation Officials (AASHTO), the Transportation Research Board (TRB), the Federal Highway Administration (FHWA), the Virginia Center for Transportation Innovation and Research (VCTIR) and the Center for Sustainable Transportation Infrastructure (CSTI) at the Virginia Tech Transportation Institute (VTTI).
The 2012 symposium focused on providing smooth, safe, quiet, and sustainable travel through innovative technologies. The symposium offered a unique platform to send a strong message about the importance of considering surface characteristics when building, renewing, and preserving roadways and airfields. SURF 2012 offered a unique opportunity for practitioners and researchers to share knowledge and expertise on this subject.
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- Miriam: An International Round Robin Test To Compare Rolling Resistance Measurement MethodsBergiers, Anneleen; Goubert, Luc; Anfosso-Lèdèe, Fabienne; Ejsmont, Jerzy A.; Sandberg, Ulf; Zöller, Marek (2012)The MIRIAM project (Models for rolling resistance in Road Infrastructure Asset Management Systems) was originally established by twelve partners from Europe and USA. It aims at developing methods for improved control of road transport carbon dioxide (CO2) emissions in order to obtain a sustainable and environmentally friendly road infrastructure. The first phase of the project, taking place in 2010-2011, included a round robin test (RRT) to compare different rolling resistance (RR) measurement equipment. The RRT was organized in June 2011 on a test track in Nantes, France. Three institutes participated with their RR trailers. RR measurements were carried out on various surfaces, such as epoxy resin, surface dressings, thin layers, porous cement concrete, porous and dense asphalt concrete. Measurements were carried out at 50 and 80 km/h to assess the influence of speed on RR. A few tyres were used to study the impact of the tyre. Many runs were undertaken on the same surface to gain knowledge about repeatability and reproducibility of the test method. Texture measurements with laser profilometer were performed on the same test sections to investigate the homogeneity of the pavements and to study the relation between texture and RR. In this paper some results, analyses and conclusions of this pilot study are presented.
- Variation Of The Observed Surface Strains Caused By Uniform And Non-Uniform Contact Pressures Using A Finite Element MethodCasey, Dermot B.; Airey, Gordon D.; Grenfell, James R.; Collop, Andy C. (2012)The current practice in pavement design is to use a circular uniformly distributed load as the input to ascertain the maximum strains in the pavement. This is not the reality; tyre-pavement contact pressure distributions are very complex. The distress on the surface of the pavement in the form of rutting and surface initiated cracking is very much dependent on these complex pressure distributions. This study investigates the effects that non-uniform contact pressure distributions have in comparison to the traditional circular loading on the initiation and rate of accumulation of this distress. The problem has been modelled using the CAPA-3D finite element software. The traditional circular load was modelled. The strains in a number of key locations were recorded and measured. Then the non-uniform loading was modelled using the same procedure. What was of particular interest was the difference in the peak surface strains and positions between the two different methods of loading. The non-uniform loading created significantly larger strains under the contact patch. The non-uniform loading also created significant shearing forces close to the surface and under the contact area. This leads to a greater propensity for the surface to develop rutting and also for cracking. The differences started to become less evident with distance from the loading area for the principal stresses. It is recommended that for the design of surface layers non-uniform contact pressures should be used.
- 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.
- On-Board Estimation of Water Depth Using Low-Cost SensorsPrevost, Delphine; Cerezo, Veronique; Do, Minh-Tan; Chabanon, Christian (2012)Last century has seen the emergence of many active safety systems, which have highly participated in reducing the number of car crashes. Nevertheless, those systems can be improved. In particular, information about the wetness of pavement surface could be of high importance to evaluate real tire/road friction. This paper deals with a new way to estimate local water depths under the tires as the car is running. A direct measurement of the amount of water droplets thrown from rotating tires of the vehicle is used. Tests are performed on test tracks with a real passenger car equipped to estimate spray and splash of water created by the front right tire of the car. Different water depths are obtained by flooding test tracks then measuring while they are drying. An indicator linked to the amount of water droplets is defined and studied under different conditions. Effects of traveling speed, road texture or tire tread pattern are assessed. The relationship between the indicator and actual water depth is verified by using non-contact optical water depth sensors as a reference. This new method of measurement via water droplets is a major breakthrough in automotive engineering since low-cost sensors can be used to estimate the water depth.
- 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.
- X-Ray Computed Tomography Observations Of Low-Noise MixesAdrien, Jerome; Carbonneau, Xavier; Lapeyronie, Vincent (2012)In recent years, low-noise mixes have met with considerable success, as they provide an effective response to a well-identified problem and produced effects that are directly perceptible by residents. The design of mixes that reduce rolling noise is based on the presence of a high voids content. At the same time, there is a tendency to reduce the maximum particle size (D) without sacrificing skidding resistance which remains excellent even in the case of mixes with 0/4 mm aggregate. The focus of conventional mix design tools is on mechanical characteristics which is generally combined, in the case of lownoise mixes, with a measurement of absorption capacities. These methods provide only an overview of the product and knowledge of the voids content, but are unable to characterize the morphology of the voids. Computed tomography can reveal this morphology in detail. This observation technique was tested on ten different mixes. After a brief presentation of the technique and the information it can provide the paper describes the tested mixes and analyzes them in terms of their acoustic performance and the detailed characteristics of their void space.
- 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.
- Ride Quality Assessment Using Probe Vehicle Acceleration MeasurementsKaticha, Samer W.; Flintsch, Gerardo W.; Valeri, Stephen M. (2012)New vehicle technology is leading to efficient methods for assessing the condition of the national highway system. Utilizing simple sensors installed in vehicles, such as accelerometers, could provide a cost effective way to assess ride quality for pavement management. This paper builds on a pilot study that compared data gathered from accelerometers to the current state of the art practices for measuring ride quality. After promising results with preliminary acceleration data, robust data collection was performed on the Virginia Smart Road under various operational conditions and using two vehicles: a Volvo truck and a Ford Fusion using the DAS system developed by the Virginia Tech Transportation Institute. Profile measurements were also obtained for comparison using an inertial laser profiler. Tests were performed at 40, 50, and 65 mph (65, 80, and 105 km/h). A GPS device was used to accurately calculate vehicle position and speed. Repeatability of acceleration and profile measurements were calculated. Effect of vehicle type and testing speed on the acceleration profile was estimated. Results show that under controlled testing conditions, roadway roughness can be accurately estimated using probe vehicle acceleration data. This suggests that instrumented probe vehicles might be a viable and effective way of implementing a pavement condition assessment program in the near future.
- 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.
- The Management Of Skid Resistance In Australia – A National, State Or Local Task?Hillier, Paul (2012)It is widely recognised that providing appropriate levels of skid resistance and surface texture across a road network can make a valuable contribution in securing positive road safety outcomes. Yet, the proactive management of skid resistance is often viewed within Australia as being within the domain and achievability of state road authorities only, despite knowledge and experience from other countries (e.g. United Kingdom and New Zealand) that a number of local road authorities (local councils) procure skid resistance testing and are actively using the data. This paper starts by introducing (and comparing) the highway network in Australia, before looking at current published guidance / good practice concerning the management of skid resistance. The many reasons for, and challenges to, the development and implementation of a skid resistance management strategy at national, state and local levels are then identified.
- 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.
- 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.
- 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.
- 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.
- 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.
- New Methods For Network Level Automated Assessment Of Surface Condition In The UKWright, Alex; Dhillon, N.; McRobbie, Stuart; Christie, Colin (2012)Automated traffic-speed surveys have been applied on the English Strategic Road Network since 2000, under the Traffic-speed Condition Surveys (TRACS) specification, which employ image and laser-based equipment to measure surface condition at traffic speed. The original requirements for TRACS surveys were based on research carried out by TRL for the Highways Agency. However, there have been significant advances in the technologies for the measurement of surface condition since 2000. The introduction of a new contract in 2012 has provided the opportunity enhance the requirements. This paper focuses on the developments undertaken in two areas – rutting and surface disintegration. Rutting is a key indicator of condition, but the laser-based transverse profile systems used to quantify rutting can be adversely affected by features such as road markings. An approach has been developed to use high resolution transverse profile in combination with surface intensity measurements to remove the influence of such features. Surface disintegration is becoming a major source of deterioration on the SRN. This has required the development of an improved assessment method, which utilizes multiple laser texture measurements to identify disintegration over the full survey width. The research has lead to the publication of a revised survey specification for TRACS.
- Simulative Polishing In The Laboratory; Comparison With Traffic And Use To Investigate Aggregate BlendingDunford, Alan; Viner, Helen; Roe, Peter; Caudwell, Louise (2012)Two experiments with the Wehner-Schulze machine, which is designed to apply a controlled amount of polishing to and measure the friction of road surfacing products, are described and their results summarised. In the first experiment the polishing action of the machine is compared to the polishing action of traffic using UK roads. It is shown that there is a strong correlation between friction measured after polishing by traffic in a non-event location and friction measured after polishing in the machine. It is shown that polishing in the machine is more severe than that applied by free-rolling traffic on straight roads. In the second experiment, the machine is used to show that it may be possible to predict the long-term friction performance of asphalt prepared with a blend of coarse aggregates using a mass ratio formula.
- 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.
- Use and Limitations of Crash Data in Determining the Priority For Treating Sites with Low Skid ResistanceViner, Helen; Coyle, Fiona; Brittain, Stuart; Caudwell, Louise (2012)In assessing the treatment of sites with low skid resistance, the relative priority of lengths marginally below skid resistance threshold where there have been a number of recent crashes must be balanced with that of lengths substantially below the threshold with no recent crash history. The judgment is complicated by the highway authority having a duty of care to maintain the road in a safe and serviceable condition, so it is not acceptable to let the skid resistance deteriorate indefinitely, even if there have been no crashes. Furthermore, the analysis lengths are generally short and the number of crashes is generally small, leading to a high degree of uncertainty in estimating the underlying risk. And finally, as there can be a large number of sites that require investigation within any particular jurisdiction, there is a need for a simple method otherwise the whole process of site investigation demands a disproportionate level of staff resource. This paper describes an accident risk model that has been created to provide a simple and consistent method for rating the priority of treatments at locations with low skid resistance and the dilemma for determining how to incorporate crash data within decisions on treatment priority.
- 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.