The authors carried out Falling Weight Deflectometer (FWD) test on asphalt test pavement that has voids in subgrade to investigate influence of the voids on deflections gained from the FWD. Followings are the main conclusions; 1) Maximum deflection and standardized deflection increases and peak time deference of maximum deflections decreases when a void exists in subgrade. In particular, maximum deflection at 1500 mm from the center of FWD's loading plate (D₁₅₀₀) and peak time deference between D₀ and D₁₅₀₀ clearly changes depending on void width. 2) Void can affects the maximum deflection when the plate is set around the void that does not exist beneath the plate.

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 Ultra high strength fiber reinforced concrete (UFC) slab was developed as a lightweight and highly durable structure for road bridge slab. The thickness of UFC slab can be thinner than the general PC slab and as lightweight as the steel plate deck. But since the structural characteristics of UFC slab are different from conventional slabs (RC/steel), characteristics of the asphalt pavement deformation on UFC slab are not be different as well.
 Therefore, in this study, finite element model of UFC slab, RC slab and steel plate deck were constructed and linear viscoelasticity analysis against running wheel load was conducted to obtain strain responses of the pavements. By comparing the strain responses of the asphalt pavement of three structure type, it was revealed that the strain response of the asphalt pavement on the UFC slab model shows different characteristics from the other structure type.

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 The dynamic backcalculation approach require the time series data of the impact force and the associated deflections. However, the majority of FWD data in the past consists of the peak load and the corresponding deflections. In this study, A dynamic backcalculation approach applicable to the peak data is developed and used in this study.
 The dynamic analysis algorithm is incorporated into the newly developed backcalculation program. Using the simulation data and FWD field data, the validity of this newly backcalculation program was confirmed.

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 A rational structural design method is needed to use interlocking concrete block pavement (ICBP) on heavy duty traffic roads. In this study, a structural model based on three dimensional finite element method (3DFEM) for the structural design of ICBP was developed. In the model, interlocking concrete block, joint and cushion sand are modeled with three dimensional solid element and interface element. The values of spring constants in the interface element were determined from FWD deflection measurement conducted on the full scale test pavement. A method for predicting permanent deflection of CBP is proposed assuming that the permanent strain is proportional to elastic strain due to traffic load. The model is expanded to predict the permanent deflection of block layer. Rut depths predicted for the test pavement with the proposed method agree well with the measured ones, suggesting the validity of the method.

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 Over 40 percent of the nationwide toll expressways operated by NEXCO has been in operation for 30 years or more. Recently some sections reveal structural damages deeper into the subbase layers. In order to take into practice an efficient and effective repair of pavements, amid structural deterioration being speculated on the increase, a new rational design approach that can match realistic requirements for repair that are demanded by each operating road. In this study, essential elements for the repair design is first to be proposed as its framework. Next, based on FWD measurements followed by an open-cut research at problematic sections, a structural index for detecting structurally damaged portions is presented. Further, by setting coefficients of materials in condition, based on laboratory resilient modulus tests, assumed as safe conditions, and FWD back calculated values as damaged conditions, effectiveness in a repair case in accordance with its proposed design structure.

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 In the previous study, we examined about a structural design method of pedestrianized pavement in consideration of users' comfort and safety. In this study, we found a meaningful relationship between impact acceleration to be measured by the road hardness test and surface modulus of elasticity (E_PFWD) to be measured by the portable FWD test, and that it was possible for a structure design with the surface modulus by using the Burmister's solution for two-layered elasticity model.
 The objective of this study is to verify a meaningful correlation between the height of safety fall to be measured by the HIC test and surface modulus of elasticity (E_PFWD) and we examined a surface layer thickness method of consideration of safety for the fall from playground equipment. In addition, this study is to verify the meaningful correlation among the HIC test, the road hardness test and simple bearing capacity test and confirmed that it was possible to alternate with two other test devices for the height of safety fall which was controlled by conducting HIC test.

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 This study aims at revealing impacts of traffic volume on the road surface temperature (RST), snow depth, and road surface friction μ along a road networks by performing numerical simulations. Our route-based forecasting model used in this study newly considers temporal/spatial variations of the μ and RST due to the difference in hourly traffic volume through vehicle related heats and snow scattering.
 The main conclusions are 1) when the road surface is slush, the μ is likely to rise in proportion to the traffic volume and the increase of traffic volume tends to shorten the recovery period of μ, i.e. period required to reach safe road surface state from dangerous one. 2) Although the RST is 0°C along a route, μ fluctuates 0.4 to 0.7. As a result, the present results imply that risk assessment of winter roads using a thermal map is not always in agreement with it using a μ-map, and that the disagreement of the risk assessment is affected by traffic volume.

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 The lack of resources and the talented person concerned with maintenance becomes the serious problem. Active introduction of ICRT is expected as one of the solutions. In late years it is in condition to be able to utilize a profit by measurement data because MMS (Mobile Mapping System) is utilized in various scenes. We think that it becomes the most effective data use to utilize data of MMS versatilely. Therefore, it is necessary to acquire data in a general viewpoint of the road management. We calculated IRI from the road surface profile that I made by data of standard MMS and inspected the usefulness of acquisition data. As a result, we demonstrated that IRI calculation was possible by the road surface profile that we made from laser and POS/LV of standard MMS.

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 Needless to say, periodic monitoring of road surface is crucial for appropriately maintaining the pavement. Standard road surface indices of rutting, cracking and roughness, however, cannot detect spotted or localized distress types, such as pumping up of loosened materials through its porosity, that are peculiar to porous asphalt. As a new way of detecting such, transverse profile at the time of measuring rutting is focused on, to propose a 3-Dimension system based on the dotted road profile data, to be able to well detect spotted surface defects. It was finally validated that the new proposed method can detect 90 percent of pumping phenomena and moreover can predict them several before actual occurrence.

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 This study developed numerical models to evaluate road surface irregularity using vertical accelerations of a vehicle recorded by a smartphone. The purpose of this study is to detect road sections with an international roughness index (IRI) of 12 mm/m or above. To achieve the objective, the authors considered two kinds of machine learning methods: logistic regression analysis and support vector machine. The discrimination ability of road surface irregularity was evaluated, and the logistic regression model showed a better result.

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 Since surface roughness induces mechanical vibration affecting vehicle passengers, it needs to be evaluated with considering human response to the physical characteristics of road profiles. This study employs the following two physiopsychological measures that are associated with surface roughness in terms of the International Roughness Index (IRI) to quantify the safety and comfort of vehicle passengers: one is perceptional reaction time that refers to psychological attentional resources for evaluating cognitive performance of humans, and heart rate variability indices that indicate mental stress corresponding to physiological changes in the autonomic nervous systems. As a result, both the long- and short- term mental stress expressed by the physiological indices increase when psychological reaction time increases significantly proportional to the increase of roughness. This result indicates that surface roughness affects not only the ride comfort but also reduction of the safety by increasing reaction time with increasing mental fatigue. This study also provides the acceptable limit of the IRI for highways as 5.4 mm/m, which supports traditional research results regarding roughness evaluation.

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 Crack ratio is one of the indices to evaluate the damage on asphalt pavement. However, evaluating crack ratio requires enormous effort and time. To solve the problem, there exist several automatic crack detection methods from the photo of road surface, but all of them suffer from the error including false detection especially when manhole or white line is in the photo. Therefore this paper have developed automated asphalt pavement crack detection method which is robust over the obstraction based on convolutional neural network which is a type of deep learning. The developed method is tested using the photos of asphalt pavements, and it is found that the method can detect cracks with very high accuracy.

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 The many functional aspects of the road are related to road surface characteristics, and it is difficult to evaluate road damage with single road surface property. In this research, we propose a new calibration method of the system correcting frequency characteristics based on the survey results of the community roads where road surface damages are anticipated. It is visually confirmed that the correlation between the tire/road noise and road surface texture is greatly high by the frequency analysis of the sound. The new method helps surveyor to identify the many distress conditions of localized defects, which have been difficult to find them.

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 The characteristics of the pavement, which the cross-sectional surface of the coarse aggregate is exposed to the surface by grinding the porous asphalt, were studied. According to the study, depending on the amount of polishing, the micro-texture of the road surface changes, hence the changes in the appearance. The more polished porous asphalt is, the glossier it becomes. The glossiness will depend on the position of the subject and the direction of the light source. With polishing, the slipperiness of the surface changes, but it is possible for pedestrians to walk. As for vehicles, low speed range is possible. Also influence the property which permeates under the road surface. Additionally, note that since this method does not need special material or design method, the limiting condition is less for the implementation.

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 The durability of pavement materials is greatly improving. For this reason, the service life of payment is going to become longer beyond comparison with the past. With long-life pavement, damage differing from that so far may be expected to occur. One such type of damage is polishing, i.e., the polishing of aggregate resulting in a decrease in resistance to slippage. Polishing will presumably appear most markedly in the case of porous pavement composed of much coarse aggregate. The authors therefore attempted to improve road surface texture by using macadam whose particles have a diameter of no more than 5 mm for the porous asphalt mixture, in order to assure a stable road surface resistance. As a result, they found that the related pavement could deliver a stable road surface resistance into the long term better than that made with the conventional porous asphalt mixture.

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 At present, various researches have been tried to clarify the property of asphalt mixture through the viscoelasticity of polymer modified asphalt. Regarding its evaluation method, easier methods have been proposed. This research was carried out to clarify the mechanism of the property of the asphalt mixture by quantifying the viscoelasticity of polymer modified asphalt through the use of popular test equipment. This test equipment used for this research is a rotation viscometer. At first, we measured the relationship between loading rate and shear stress. Secondly, we made the master-curve of some kinds of modified asphalt by employing time-temperature superposition principle. Finally, we experimentally verified the relationship between the characteristic values obtained from the master-curve and the properties of asphalt mixtures. As a result, it was clarify that there was a clear relationship between both properties.

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 This study aims to examine a fatigue failure characteristic of an asphalt-stabilized base course mixture with consideration of temperature, loading-time and strain level. Four point bending fatigue tests at various temperatures and strain levels were conducted. It was found that the number of cycles to failure was affected by temperature and there was a good relationship between the number of cycles to failure and the dissipated energy. Using this relationship and the time-temperature superposition principle, we can calculate the number of cycles to failure at voluntary temperature, loading-time and strain level. These data are usefull to predict the timing of fatigue failure occurrence.

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 The amount of social capital maintenance costs is tend to be decreasing with a Japanese aging society. However the road maintenance which is the keystone of social capital maintenance is absolutely imperative. Supply of the asphalt mixture in a sustainable manner is essential into the future.
 Percentage of recycled asphalt material mixtures in the total asphalt production reached approximately 75 % in recent years. There are concerns over the compromised quality due to multiple recycling. Existing pavements are a social capital stock and valuable resource and they need to be recycled with ensuring quality continually.
 The quantities of asphalt mixtures produced for the road pavement material have been decreased year by year with the reduction of the investment in maintenance. There are rising concerns over the stable supply of asphalt mixture throughout Japan.
 This report presents the outline of the future direction by introducing foaming technologies to ensure the quality of Recycled asphalt mixture and to expand supply area by extending its usable time.

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 The history of recycling asphalt pavement in Japan is long, and in recent years reclaimed asphalt pavement (RAP) ratio in recycled asphalt mixture has also increased. Therefore, the amount of RAP that is repeatedly recycled will be increased in the future. However, there are still few findings concerning the changes in material properties and mixture properties that were repeatedly recycled. In this research, in order to analyze the properties of asphalt and asphalt mixture for repeated recycling, asphalt was aged and recycled repeatedly five times in the laboratory, then the asphalt material properties and mixture properties of recycled asphalt and recycled asphalt mixture were examined. As a result, some useful data were obtained and there were reported.

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 Recently, long-term effective utilization of resources is required. The use of recycled aggregate has expended and the shipment ratio of recycled hot mix asphalt mixtures is increasing. However, the aged deterioration has still been examined, especially the chemical property is not sufficient. In this study, the chemical property was examined using the asphalt cores that were taken from the current road laid the recycled asphalt mixtures with different recycling methods. In addition, deterioration progression in the depth direction of the recycled asphalt mixtures was compared with the long-term asphalt mixtures and further deterioration progression was considered.

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 Various types of buckling prevention plates have been developed to increase lateral resistance of sleepers in ballasted tracks to reduce rail buckling potential. This study conducted scaled model tests to investigate effects of the plate size and the shape on the lateral resistance. It was found that the lateral resistance did not always increase with the increase of the plate area. The plate embedment depth significantly contributed the increase of the lateral resistance, while the plate width did not affect so much. This tendency was remarkably observed in single sleeper pull-out test results rather than track panel pull-out test results. The contribution of the plate width to the lateral resistance was relatively increased in the track panel pull-out tests. This was probably because the mobilized mechanisms for the sleeper side resistance in the tests were different from those in single sleeper pull-out tests. It was also found that the lateral resistance per one sleeper in the track panel pull-out tests was lower than that in the single sleeper pull-out tests. This was due to the effects of the piled group.

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 In this study, we developed the new ballstless track reusing existing ballast with high fine-particle content. Superfine-particle cement milk was applied as the grout material for the ballastless track. It was confirmed that superfine-particle cement milk showed high filling performance for degraded ballast and had early strength development. We carried out the cyclic loading test for full-scale track model and confirmed the high restraining effect on track settlement.

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 Regarding pavements in cold regions, it has been reported that vertical stresses in the ground at the depths where water or gas pipes are buried greatly changes along with the freeze-thaw cycling. In addition, it has also been revealed that incremental stresses in the ground due to vehicle wheel loads from the road surface changes along with freezing and thawing.
 In this study, we investigated the effects of freezing and thawing under pavement on the relationship between the magnitude of the wheel load and the incremental stress in the ground, using vehicles of two types, which were of greatly different weights. We also investigated the effects of freezing and thawing on the stress distribution (transmission) in the ground, using a large scale soil container to simulate a paved road.
 As a result, we found that the incremental stress in the ground increases with the vehicle weight and that the rate of increase changes with freezing and thawing. The stress distribution in the ground was also found to change with freezing and thawing.

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 In snowy cold regions, the base course and subgrade are exposed to freezing in winter and increased water content during the thaw, and these layers see decreases in load bearing capacity from freeze-thaw. Therefore, it is crucial to understand the frost penetration depth and number of freeze-thaw cycles of the pavement, and the variation in water content of the material, towards establishing paving methods that are appropriate for snowy cold regions. In this study, we conducted a basic study on evaluating the freezing and thawing of pavement body materials such as base course and subgrade according to their changes in electrical resistance. We prototyped a sensor on which many electrodes were placed at regular intervals, installed the sensor in base course material and subgrade soil ground in a laboratory, and measured the electrical resistance when the materials were subjected to freeze-thaw. It was found possible to use the electrical resistance values to determine whether the materials were frozen or not. We also installed the prototype sensor in ground outdoors in order to determine whether the soil was frozen or not by using a self-recording device that enables AC voltage measurements. We found that the sensor can measure the soil's freezing and thawing continuously in the depth direction, and that it is effective for measuring the frost depth of the soil.

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 In this study, FWD test was adopted on before and after asphalt pavement repair work site where the repair methods were selected based on the result of core test survey, also the road surface survey was done at the same time. From the results of these investigations, it was confirmed that the damage conditions in the asphalt mixture layer were varied among the same repair work site, and repair methods according to crack depth obtained by core test survey contributed to the recovery of the durability of the pavement to an almost uniform levels.

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 For paving stocks where aging progresses, it is necessary to construct PMS in order to ensure both safety and comfort and maintenance and repair cost reduction. By using PMS, it is possible to promoto the repair PDCA cycle. A database is essential for PMS, but the database of NEXCO has a problem.
 This paper reports on rebuilding the database.

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 Load bearing capacity declines by being used over time and the speed of decline differs because of many internal or external factors. The decline of load bearing capacity of pavement is deeply related to deterioration of structural or functional soundness and thus repair enabling utmost recovery in load bearing capacity should be made in the optimal timing. In this study using FWD survey data, the authors estimate the deterioration hazard model that each pavement layer's deterioration process depends on, and draw performance curves, considering the difference of the speed of deterioration between before and after repair.

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 In order to realize effective pavement maintenance and management, it is necessary to predict the future state change by prediction of pavement deterioration and to optimize the maintenance and management cost such as inspection, repair, renewal etc. Various pavement deterioration prediction models have been proposed, but it is not easy to determine under what circumstances each model is best.
 Therefore, this research proposes time slice cross validation that can compare realistic prediction accuracy of prediction model to inspection history data having time information with each other. The proposed method divides time series inspection data in the time direction, estimates parameters of the model from the learning data, and performs realistic prediction accuracy evaluation by using the prediction result of the test data using the parameters. We applied the proposed method to pavement deterioration prediction by RNN model and verified that future prediction accuracy can be more realistically evaluated than conventional method.

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