Base courses and subgrades in cold snowy regions are under severe conditions, subject to the influence of freezing during winter and the weakening of bearing capacity due to freeze-thaw processes. Thus, when constructing pavement in a cold snowy region, it is important to determine the frost penetration depth and freeze-thaw state of the road. Fundamental experiments were conducted to examine a method for estimating the freeze-thaw state of base course materials and subgrade materials based on variation in electrical resistance. As a result, it was confirmed that the method was effective for estimating the freeze-thaw states of these materials. In this study, sensors containing numerous electrodes, which were arranged at regular intervals, were installed in the subbase course and subgrade to measure electrical resistance during the freezing and thawing processes, frost penetration depth, etc. As a result, it was suggested that this method could be used for measurement of the frost penetration depth and determination of the freeze-thaw state.

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 Water pipes laid intensively during the period of rapid economic growth are all now degraded, so their improvement or renewal nationwide is urgent. As a result, the study and execution of shallow burying based on deregulation are underway in order to reduce costs and shorten the renewal period in warm regions. A cold district like Hokkaido requires water pipes to be laid basically below the frost penetration depth. Even in such a region, it is important to work on the extent to which the pipe can accept shallow burying. In this research, we have used a two-dimensional heat transfer analysis to review the burying depth in detail according to the earth temperatures measured around water pipes laid under a paved road in Kitami City in the eastern part of Hokkaido and in consideration of frost risks.

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 In this study, cyclic loading tests were carried out on model grounds simulating the conditions of track and roadbed in the clayey roadbed section of the Tokaido Shinkansen, in order to verify the mechanism which causes frequent maintenance locations. Effects of the ballast layer thickness and the water intrusion on the track settlement were investigated. The model grounds were set to 1/5 size of the real ones, and based on the field survey results, they were consisted of three layers of ballast, fouled ballast and ballast mixing loam, respectively. The test results show that as the ballast layer thickness (the sum of ballast and fouled layer thickness) decreases, the settlement amount in the initial stage of loading become smaller, but as the saturation degree of the roadbed surface layer increases the settlement rate becomes higher because the earth pressure acting on the roadbed surface become higher and the road surface softens. It was also found that the thicker ballast layer can significantly lower the settlement even though the degree of saturation of the roadbed is increased.

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 The authors constructed asphalt test pavement and generated various size of cavities in subgrade of the pavement. Pavement behavior such as permanent deformation and strain were investigated during repetitive loading test to characterize the cavity that could induce subsidence of pavement. The surface permanent deformation above the cavity whose width was 2m was 40mm after 5 laps of aircraft loading were applied on the asphalt layer of 20°C. Then, the site showed a symptom of destruction at 6th lap. The deformation above the cavity whose width was 1m was 65mm after 35 laps of aircraft loading were applied on the asphalt layer of 25~29°C. The site above the cavity whose width is over 1m could subside in few repetitive aircraft loadings when the temperature of asphalt layer is more than 25°C.

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 50 years have passed since the opening of the Tomei Expressway. Pavement is getting old. NEXCO has to carry out the most suitable repair at pavement at low cost . Using the data accumulated in the database of the pavement management system, we considered the long-term serviceability of the pavement in the Tomei expressway. As a result, it was found that pavement with a long year of use tends to have a small deflection amount on the road surface. It also shows the proportion of sections that require repair of pavement for each year of use.

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 Porous asphalt pavement (drainage asphalt pavement; DAP) has been widely used mainly in national highways and expressways since the "Drainage Asphalt Pavement Technical Guidelines" was published in 1996. Also, more than 20 years have elapsed since DAP began to popularize, and the recycled aggregate due to reconstruction on DAP is expected to increase in the future. However, since polymer-modified asphalt with high adhesive strength is used for DAP, and since aggregate gradation is largely different from dense graded asphalt mixture usually used, the recycling method of DAP is considered necessary. In this study, the recycled DAP which was made of recycled porous asphalt mixture and dense graded asphalt mixture, were constructed in December 2006 and March 2007 in National Highway No. 408 of Tsukuba City, Ibaraki prefecture. And the results of follow-up survey on durability and serviceability for ten years of recycled drainage asphalt pavement were reported.

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 Achievements of various studies have been piling up recently with a view to the continuous recycling of reclaimed asphalt pavement (RAP). But there are still many ambiguities as to the optimum percentage of recycled aggregate content and the efficacy of rejuvenators. For this reason, the sustainable use of RAP is not yet secured. The hydrothermal decomposition method utilizing the solvent property of high-temperature and high-pressure water is currently applied in the process of modifying oil sand bitumen, for example. And, we have confirmed the potential effect of old asphalt properties being recovered in the process of developing an asphalt extractive test using high-temperature and high-pressure water as a solvent. In this research, we took note of the hydrothermal decomposition method with water as hot as 200 to 350 degrees C since this method was known for many examples of application. We have examined the process of old asphalt properties gaining recovery in that particular method. Confirmed as a result of the hydrothermal decomposition method is the possibility of old asphalt reviving its original raw material state, by and large, in the chemical as well as physical properties after being decomposed into low molecules and then reduced in its oxidization.

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 The number of the new road construction is expected to decrease. On the other hand the number of road maintenance and repair construction will be possibly to increase. The supply of the asphalt mixture for the existing roads is absolutely imperative. However the investment in construction in Japan is shrinking every year. Therefore, the quantities of asphalt mixtures produced for the road pavement material have been decreased year by year and the elimination and consolidation of the asphalt plant has same tendency as the number of the quantities of asphalt mixtures produced. In the near future, it would be concerned about the appearance of the road where asphalt mixtures will not be supplied. However there is no detailed grasping method of the scope of the asphalt mixtures supply.
 This study aimed to analyze the detailed scope of the asphalt mixtures supply by using the road network data and to suggest the approach for the sustainable supply of asphalt mixtures.

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 In the near future, it is expected that production of reclaimed asphalt pavement which does not satisfy the quality standard (below-standard RAP) will increase. The authors anticipated that the below-standard RAP could be effectively used as a material for recycled hot mix asphalt (HMA) mixtures, when the adding percentage was reduced. The present study evaluated performance of the recycled HMA mixtures in order to consider the validity of the authors' anticipation and to obtain related fundamental information. As a wearing course HMA, the potential for moisture damage and the cracking resistance of the recycled mixtures were assessed by some laboratory tests. The following findings were obtained. The recycled HMA mixtures were strengthened due to adding the RAP, however brittleness increased and cracks were easy to progress. The below-standard RAP could be utilized for wearing course recycled HMA mixtures by adjusting the adding percentage.

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 After the Great East Japan Earthquake, the use of nuclear power generation is decreasing. Along with this, the use of thermal power generation is increasing. Especially, coal-fired power generation has greatly increased the utilization rate, and now it accounts for 32% of domestic electricity generation. Also about 12 million tons of coal fly ash is generated as a by-product annually, and it is increasing year by year. Since the physical properties of limestone powder and coal fly ash used as a filler material have similar physical properties, this study carried out to investigate the effect of physical properties, leaching properties and workability when coal fly ash was used as an asphalt mixture filler material. In this report, the physical properties and leaching properties of asphalt mixture using coal fly ash and site operation results are described.

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 In recent years, the demands for cycle tourism increases with increasing awareness of environmental protection and the healthy life. In promoting cycle tourism, the road surface condition for traveling is one of the important factors affecting the safety and comfort of cyclists. However, no evaluation index of surface roughness has been developed with respect to the ride quality for cyclists. This research develops a bicycle vibration model for evaluating road surface roughness in terms of bicycle ride quality. For this purpose, we estimate the frequency response function of a common bicycle by performing a vibration experiment using a vibrating table. In the experiment, two accelerometers were attached to the bicycle: one was to the handlebar and the other was to the wheel rim. The result shows that the bicycle has two distinctive resonance frequencies on 10 and 20 Hz corresponding to the handle and wheel rim respectively. Thus, we develop a bicycle vibration model based on a damped two degree-of-freedom system. Finally, the effectiveness of the model is verified in terms of vertical acceleration compared with the experimental result. The outcomes of this research contribute to the evaluation of surface roughness from the viewpoint of bicycle ride quality with the same idea to the International Roughness Index (IRI).

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 This paper applies the exploratory spatial data analysis method to grasp the spatial autocorrelation which is seen in the crack rate, rutting amount, IRI for the highway in Shikoku region. We find the hotspot locations and their properties that are more susceptible to degradation than other road sections. We also quantitatively evaluated factors which are influencing the degradation rate of crack rate using generalized linear mixed-effect model. As a result, we find that the structural conditions such as banking and cut soil have a significant influence on the deterioration rate of the crack rate in hot spots.

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 The high-performance SMA was incorporated in the design procedure of the MLIT Hokkaido Development Bureau in 2016 and has been widely used mainly in arterial high-standard highways. However, although the high-performance SMA ensures traveling safety, it is necessary to improve the durability further because the pavement maintenance and recondition budget decreased largely compared with that of 20 years ago. Improvement of the durability to extend the life of pavement is becoming a social need. Therefore, this study, as a part of studies aiming at the improvement of the durability of high-performance SMA, clarified the relationship of durability and road surface texture when changing the aggregate gradation of the high-performance SMA. Moreover, the indicator to determine the road surface texture (MPD: mean profile depth) required to ensure the traveling safety function was aimed to be established by the study. As a result, it was found that 1) the mixing rate for the high-durability of the high-performance SMA causes the MPD to decrease, which may lead to degradation of traveling safety, 2) traveling safety can be ensured even if the MPD is decreased to 0.5 - 0.7 mm.

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 In this study, we aimed to detect and evaluate the local deterioration noticeable in drainage pavement by conducting Short-Time Fourier Transform of pavement surface displacement data in three-dimensional point cloud data. Based on the verification on the actual road, it is possible to exhaustively detect the local deterioration using the maximum value of the amplitude spectrum obtained by calculating Short-Time Fourier Transform of whole pavement data. We also pointed out that the mean value of the amplitude spectrum is linearly correlated with IRI, and showed that it is possible to diagnose the degree of deterioration of the pavement before local deteriorations become obvious. We also conducted parametric studies in calculating these indices. The results of this research showed that we could automate the detection of the local deterioration of pavement. This technology can be also applied to degradation patterns with other scales and to other object surfaces.

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 Porous asphalt becomes standard surface mix on the expressways in Japan. This type of surface tends to face spotted defects, such as pumping, alligator cracks lead to potholes, unlike conventional dense asphalt surface, caused by stripping phenomena in the base course mix. This feature of damage causes difficulty of the use of traditional measurement to detect the place, because of its location spot by spot. Therefore, we have been developing a new extraction method and showing its possibility, by using converted road surface measuring data into 3-Dimension clouds profile data. However, proposed method takes rather long time to analyze, not enough capable to evaluate all of surfaces on the existing expressway networks. Hence, further study is conducted to shorten the analyzing time to detect the spotted damage on the porous asphalt surface, by deep learning method with the converting corrected 3-D clouds profile data into color information image of multi–stages.

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 In this study, we developed the high-resolution detector for crack and patching on pavement of expressway by using convolutional neural network (CNN), and culculated the crack ratio by this method. First, small images such as crack and patching area was randomly sampled using sketch images. We set several image sizes to make the judgment by CNN. Then, the size and the judgment accuracy of the model were compared. As a result, over learning of models was observed for larger sizes, and accuracy of model reached a peak at an intermediate size. Cracks and patching were detected by the learned model, and the crack rate was calculated based on the conventional method. From the above results, it was shown that the accuracy of crack ratio is high with t he judgment image size of 90 pixels, and the crack shape can be visualized in detail.

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 Localized damage of porous asphalt cannot be evaluated by rutting-cracking-IRI which are conventional damage evaluation indexes of pavement Surface aggregate peeling due to deterioration of binder is scattered over a wide area of the Shizuoka prefecture section of the Tomei Expressway .Since this damage cannot be evaluated by the conventional evaluation index we investigated the new index to evaluate the area of surface aggregate peeling the traverse profile data. We also tried to visualize the damaged state by coloring the surface aggregate peeling on a view of upper surface. As a result the more evaluation criteria (Level I, II, III, IV, V) Progressed by deterioration evaluation method The more area of surface aggregate peeling increased.

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