At airports in cold, snowy regions, winter runway surface conditions that prevent airplanes from landing may occur because of decreased skid friction coefficient due to snow and ice, causing inconvenience to users. To improve the skid resistance of runways, the authors focused on high-performance SMA, which forms a rough pavement surface, and considered its application as a surface mixture for runways through laboratory experiments and test construction. The results demonstrated that the technique was effective in improving the friction coefficient under conditions of slush or black ice on the runway surface. In the laboratory experiment, which evaluated freezing and thawing unique to cold, snowy regions as well as durability and other properties, high-performance stone mastic also displayed a level of performance equaling or surpassing that of dense-grade asphalt concrete 20F. a standard surface mixture. SMA's effectiveness as a measure for winter runway surfaces in cold, snowy regions was confirmed.

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The purpose of this study is to find statistically-significant number of subjects in a driving experiment that investigates the level of passenger acceptance of pavement roughness. Statistical power analysis is used to determine an appropriate sample size as a function of a significant level, effect size (ES) and statistical power. In power analysis, the ES basically depends on the purpose of each individual study. Therefore, we estimate the ES to evaluate the acceptance ratio of roughness based on a subjective rating by a driving simulator. Consequently, over 20 subjects in the experiment allows one to compare the acceptable proportion of two vertical accelerations split by more than 0.35m/s2 in the root-mean-square value that is medium or large ES. Conversely, the small ES offered by the acceleration difference of less than 0.3m/s2 requires a large number of subjects such as 400. If the required number of subjects is not obtained, we recommend that the statistical confidence interval should be calculated and the result of the experiment should not be generalized for the road surface evaluation.

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This paper deals with a development of a new, quantitative and objective index of ride quality of pavements. A driving simulator that reproduces the behavior of vehicles traveling on uneven road surfaces was used for subjective evaluation of ride quality. At the same time, the variation of heart rate was measured. From the results, it was found that the test subject's heart rate increased when driving on the uneven roads, and as the vertical acceleration R.M.S. value increased, the variation of heart rate increased. It was also confirmed that as the variation of heart rate increased, the subjective evaluation of ride quality decreased. Linear regression analyses shows that the subjective evaluation could be described with the variation of heart rate as an explaining variable. The differences of each subjects' sensibility to vibrations should be considered to develop a generalized model.

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A method for predicting development of rut depth in asphalt pavements in Hokuriku region was developed by applying Neural Network System (NNS). A three layer NNS with input nodes for IC section, subugrade type, lane type, surface type and the number of large vehicles and an output node for rut depth was employed. The model was established by inputing performance data of asphalt pavements in Hokuriku region. The predicted relationship between rut depth and the number of large vehicles agrees well with observed ones. The effects of the input parameters on rut depth development were discussed based on the predicted curves.

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Yokohama City is managing 7, 400km of roads. It is expected that roads should be renewed in the future and increasing maintenance/rehabilitation expenses will become a big load for the city. Yokohama City is implementing since 2005 in order to introduce an asset management system of the pavement. Especially, the evaluation manual of the road by watching was made and united evaluation was executed for 6, 500km of community roads that 90 percent of all road networks in Yokohama City.

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The temperatures of pavement of servicing road reach 60 degrees Celsius in summertime. The stiffness of asphalt mixture is often measured by resilient modulus test or uniaxial compression test at normal temperature. But, measurement method at high temperature is not defined. And shape of specimen also influences measured values in such condition. In this research, the measurement of asphalt mixture at high temperature using uniaxial compression test is investigated. As a result, the measurement method and the shape of specimen are proposed and the stiffness characteristics of dense grade asphalt concrete, porous asphalt concrete, stone matrix asphalt concrete and mastic asphalt concrete are measured.

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In this study, the asphalt deformation of asphalt contained large stone was investigated in micro area. First, we measured by compression experimentally coefficient of longitudinal elasticity for small asphalt model specimens. Specimens have several volume fractions of reinforcement. In addition, finite element analysis of the model specimens was preceded for coefficient of longitudinal elasticity and distribution of stress and strain. Furthermore, a few composite laws were adapted these specimens. They, however, were limited by volume fractions. Therefore, based on the results of analysis and experiment, the variables of several mechanical properties and dimensions of stones in composite models changed to investigate for the minimum strain values of composite matrix. The results showed that structure of composite materials is more effective to optimize. Larger stones have near the surface, or, in intermediate layer have small stones that are better under the adaptive conditions.

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We have already demonstrated that electromagmetic wave interference method can determine the packing conditions of drainage pavement by introducing a vector diagram. But a packing definition does not completely correspond to only one condition. That might bring some ambiguities on the diagram. Numerical simulations have shown that not serious but small ambiguities occur on the diagram. We also carried out measurements on actual roads, one for fresh pavement and the other for the pavement of one year old. Packing transition has been observed in a couple of months range on fresh pavement. However, on the pavement of one year old, where various degrees of packings exist, the significant transition has not been observed in a month range. This simultaneously shows that the method is reproductive.

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The permeability design in the design method of a permeable pavement makes the trial calculation of the road metal and pavement thickness to be used so that the permeavility capability demanded according to an application part may be satisfied. It is determined as compared with the structure required in a structural design. Saturated hydraulic conductivity is estimating the permeable ability in that case. However, the rainfall initial permeates in the state where a inside of pavement is unsaturated. Then, this research measured the water retention characteristics of a permeable pavement.

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In Japan, the Reclaimed Asphalt pavement have been widely used, and it works effectively as recycling materials. However, it does not make clear about the amount of environmental loads (CO2 emission, etc) through the lifecycle, such as material production, transportation, construction and rejection. Then, we evaluated environmental load through the lifecycle using general method of reclaimed asphalt pavement and in-place recycling method.
The result is that the amount of CO₂ emission of off-site recycling method is obviously fewer than its using new material, besides that in-place recycling method is even smaller than the others. However, it reveals that CO₂ emission is increased, in case of the construction machine for in-place recycling is transported for long distance, In that case, it is necessary to consider selecting this method.

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Recently, the development of the recycled resource is active in the background of effective use of the resource and the depletion of the final disposal dump, etc. Especially, the development of the technology used for the pavement of those recycled resources is active. Using these recycled resources comes to recycle certainly. However, whether it has contributed to the environmental load decrease in total until abandoning since using these manufactures it is not clarified. Then, the resource consumption, the saving resource, and the environmental load when using it for pavement were provisionally calculated for scrap tire and waste plastics, and LCA evaluation was examined. As a result, it was shown overall might decrease the environmental load though the recycled resource pavement might partially increase the load.

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The properties of straight asphalt used in cold, snowy regions were studied by repeatedly recycling it with a penetration value of 20, which is the current lowest standard for old asphalt used as recycled aggregate. The results showed that straight asphalt with a penetration value of 80 to 100 was more susceptible to degradation and types of rejuvenator than the straight asphalt 60-80 used in Honshu and other areas, and its chemical and physical properties varied widely. A study to simulate repeated recycling of straight asphalt 80-100 also revealed the possibility of reducing the rejuvenator amount and fluctuations in physical and chemical properties by choosing an appropriate type of rejuvenator.

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In Japan, several mix design methods for the recycled porous asphalt are being developed and proposed. These methods include the one to use Cantabro test and the one by the extraction recovery of asphalt. However, they have not been established yet, because they have some problems. The authors studied the mix design method using asphalt mortar, the new method evaluating several properties without extraction. As a result, the new mortar method was a method of not only appreciable of servicing temperature but also appreciable of constructing temperature. In addition, the labor of the method was also light.

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Cement foamed asphalt (CFA) stabilized base that is one of the pavement recycling methods utilized on the roads has been noticed widely, because the global environmental protection and preservation is generally recognized to be necessary in these days. However, cement sometimes scatters when it is spread and mixed in the sites, so it is afraid that the scattering cement would influence on workers' health and the surround environment. In this study, the construction method using cement slurry was thought up against scattering cement. The mix design of CFA base mixture with slurry cement was conducted and the machine to spread the cement slurry was developed. The accelerated loading tests were conducted in the trial yard with the pavement cross-section for the traffic class N₃. From results of the tests, it was found that CFA stabilized base has superior durability in view of surface condition, structural capacity and material properties.

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This paper describes the applicability of soil-water coupled analysis for simulating the constant volume direct simple shear behaviour of statically compacted granular materials. Multi-stage constant volume direct simple shear tests are carried out for investigating the consolidation and simple shear behaviour of granular materials. The constitutive model mainly employed in the calculations is an elasto-plastic model developed by Sekiguchi and Ohta (1977). The calculated results are compared with actual laboratory test data. The small strain behaviour of the constant volume direct simple shear is well correlated with calculated results.

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The paper proposes a new analytical procedure with discontinuous analysis to estimate the bearing capacity of granular roadbed used in ballasted track or road pavement. To examine the applicability, a series of numerical simulations bearing capacity tests for 1/5 scale model of real ballasted track were performed with DDA that regards a particle of crushed stone as an irregular polygon. Based on the comparison of analytical results with experimental results, the effect of subgrade stiffness on the bearing capacity of granular roadbed was examined. As the result, it is revealed that the subgrade stiffness has a great influence on the bearing capacity of granular roadbed, and that discontinuous analysis is an effective method to simulate the mechanical behavior of granular roadbed if the subgrade which behaves as a continuum can be approximated with discontinuous modeling well.

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A program package for analysis of block pavement based on 3 dimensional finite element method (Block-Pave3D) was developed. In the structural model of BlockPave3D, each block is divided with solid elements. Joint and cushion layer are replaced with interface elements. This modeling allows to take into account effects of laying pattern and geometry of block on deflections and stresses of block and subbase. Spring constants in the interface elements were estimated by a method based on portable FWD and Neural Network system (NNS). In the model, relationship between FWD deflections and combinations of spring constants was obtained from learning process of NNS. Stress analysis were conducted by BlockPave3D using spring constants estimated from the portable FWD deflections on the actual block pavements.

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Thermal stress caused by temperature distribution in pavement slab is important in the structural design of airport concrete pavements. Airport concrete pavement slab is very thick, therefore, temperature in the pavement slab varies nonlinearly throughout the slab depth. Thermal stress caused by the nonlinear temperature distribution would be different from that of linear temperature distribution. In this research, following issues were investigated to evaluate the thermal stress in concrete pavement. 1) Thermal stress caused by nonlinear temperature distribution was calculated using temperatures and restraint strains measured in an experimental concrete pavement with a 46cm thick slab. 2) Temperature distribution in concrete pavement was evaluated by thermal analysis. 3) Thermal stress was calculated considering the nonlinear temperature distribution by 3DFEM.

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Structural evaluation of pavement structure is performed by static backcalculation using peak loading and deflections values. Backcalculated moduli reflect on various errors and their magnitudes have been reported. Dynamic backcalculation is more suitable than static backcalculation because FWD is an impulsive loading test.
However, effect of errors due to dynamic backcalculation has not been examined. This paper identifies the effects of modeling errors, measurement errors and lack in synchronization on backcalculated results. Dynamically backcalculated results are compared with statical results and difference in those results is examined.

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This paper reports an investigation on liquefaction experiment site. In the experiment, surface deformation and FWD deflection were measured on asphalt and concrete pavements which were on improved ground for liquefaction or unimproved one. The result showed that difference of elevation between pavement on improved ground and unimproved one were approximately 30 cm at most. The transformation of surface deformation continued for only a few hours. FWD deflection just after liquefaction exceeded that before liquefaction, and deflection kept decreasing for about seven day

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The first process of introducing a theoretical method into the design of asphalt pavement is to set the modulus and Poisson's ratio for each pavement layer. The numerical value gained by it significantly affects the subsequent multilayer elastic analysis. Unlike the temperate regions in Japan, however, cold and snowy Hokkaido has a history of setting unique regional standards of binder penetration, granular grading as well as other properties. In addition, the modulus for each pavement layer in the cold areas in Japan and those in the warm areas tend to be different. In this study, in order to establish a multilayer elastic theory for cold and snowy regions, the modulus for each pavement layer will be examined. This is based on FWD measurement results obtained from pavement testing on the major national roads in Hokkaido. The relationship between the temperature and the modulus of elasticity in an asphalt mixture layer and the range of modulus in granular will be explained.

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For the purpose of establishing a repair design method of asphalt pavements for the Japanese expressways, an efficient method of damage evaluation that does not need core sampling was studied for development. According to analyzing FWD data and sampled cores near the falling point, deflection difference (D0-D90) divided by asphalt layers' thickness was found practically distinguishable from safe layers to those damaged. From materials testing of the cores, it was also found binder course mix for porous asphalt is to be with higher resilient modulus and splitting resistance.

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