We developed a device that measures the thickness of the water film on the road surface by using a vehicle-mounted salinity sensor and water splashed from the road surface by one of the vehicle's tires. The measurement accuracy was verified through a driving test. The following are the findings. (1) We developed a sensor for measuring the combined salinity of the water supplied from inside the vehicle and the water splashed by the tire, and we propose a theory whereby the salinity of the water on the road surface and the combined salinity can be used to determine the weight of splashed water. (2) The thickness of the water film on the road surface and the weight of splashed water were found to have a power relationship. For the same the weight of splashed water, the thickness of the water film is thinner when the driving speed is faster. The relational equation obtained from the above relationship enables measurement of the thickness of the water film on the road surface from the weight of splashed water and the driving speed. (3) The device was found to possibility of measuring the water film on the road surface with accuracy on the order of 0.1mm, an accuracy that is sufficient to contribute to solutions to problems related to road surface freezing.

 In the past research, research results on the road pavement deterioration predictions are accumulated and have been used for asset management. Many of them, use probabilistic deterioration predictions to support with the uncertainty deterioration process. However, any verified research might not been found for deterioration prediction results analyzed by the actual measurement results. So, in the main research, the deterioration curve was constructed from survey results of the road surface property about representative parts in the Kanto Maintenance Area and it verified by the actual measurement results. Concretely, tendency of the selected representative parts were analyzed, and locally deteriorated parts were excluded to construct the deterioration curve. The deterioration curve was constructed by the least squares approximation (straight line, curve) and Markov equation. For the constructed deterioration curve, the consistency between predicted value and road surface property were confirmed, and the remember points were organized for construction of the pavement deterioration curve.

 This study is to analysis the deterioration of the asphalt pavement based on the inspection data of the national roads, focusing on the crack rate of the asphalt pavement at the transition process from stage II (maintenance stage) to stage III (repair stage), which were stipulated by the guideline of the pavement inspection issued at Oct. 2016. In the analysis, it was found that the deterioration progress of the crack rate for one year has statistically almost normal distribution, and we proposed a statistic method to predict the deterioration progress of the asphalt pavement. In addition, the concept of the reliability was introduced into the prediction method and the deterioration progress speed was calculated for each category of the traffic volume with the reliability. And we showed the occurrence probability of each stages on the deterioration of the asphalt pavements in the future across Japan.

 We developed a system that performs visual inspection on PC using moving image taken with an action camera mounted on a traveling vehicle. The pavement with measured crack rate was visually evaluated by subjects using this system, and it was found that the inspection accuracy would increase by repeating the training, and the method to improve the visual inspection accuracy was devised. Trained subjects performed visual inspection of 6 sections using this method, it is cleared that the detection rate (Level II+) and the hit rate (Level III) were rank A (80-100%), the detection rate (Level III) and the hit rate (Level II+) were rank B (60-80%), which proved to have sufficient inspection accuracy.

 Central Nippon Expressway Company regularly conducts visual surveys of pavement in daily inspection of road structures. As the survey is conducted by multiple inspectors, the inspectors may have different report contents even if they look at the same road surface deformation. In addition, visual survey results are not always used for planning of large-scale repair such as overlay after scalification. In order to make effective utilization of daily inspections, the authors investigated the current state of visual surveys, extracted issues, and considered improvement measures. As a result, it was confirmed that inspectors differed in terms of reporting method when damage occurred complexly and the language for explaining the outline of damage. This report reports improvement measures for those problems and how to use visual survey for large-scale repair plan.

 We extracted the pavement distress where ambulance crews payed attention when driving an ambulance in the road of the Kushiro-Nemuro area where long-time transportation by ambulance frequently occurs. The distress was classified into four types: bridge joint faulting, longitudinal cracking, low-temperature cracking, and roughness, and the IRI should be maintained more than 4mm/m in those distress.Anew repair method for bridge joint faulting was applied and the effects and problems became clear. The relationship between the frequency of low-temperature cracking and the vehicle vibration was analyzed, and it was found that the low-temperature cracking affects the vehicle vibration more than the bridge joint faulting as the interval of low-temperature cracking becomes shorter.

 Running or jogging is one of the easy exercises for all the people regardless their ages. From the past research, runners feel comfortable when they run on pavements in the aspect of pushing off with their feet and touchdown impact. However, it does not figure out what are associated indices with pavement. The authors found that surface texture is highly related with runners feeling and/or sense when running. And then surface texture indices including MPD, skewness and kurtosis are proposed to evaluate the pavement condition that runners feel comfortable. Also, the authors propose what type of asphalt pavement is preferable for runners.

 This paper presents the results of a study of methods for indirectly evaluating the rolling resistance coefficient from a road surface profile. In this study, a road surface profile was divided into two regions: a macrotexture region and a mega-texture roughness region (hereinafter “the roughness region”). We performed an analysis of two-dimensional texture data in the macrotexture region and a wavelet analysis of one-dimensional profile data in the roughness region. As a result, we were able to propose a multiple regression equation to estimate the rolling resistance coefficient using as an explanatory variable the RMS value obtained from a 0.5 mm surface area in the macrotexture region and the RMS value obtained from a profile in the wavelength range of 0.08 to 5.12 m in the roughness region. The correlation obtained between the tire/road rolling resistance coefficient is stronger than that obtained using MPD or IRI as an explanatory variable.

 In recent years, cycle tourism has been attracting attention in Japan. So improvement of pavement, which greatly affects bicycle driving environment, is important in promoting cycle tourism. However, an evaluation of road surface roughness as seen from a bicycle has not been established. this study, we verified the reproducibility of the newly developed bicycle vibration model on the actual road surface, and constructed the road surface evaluation index of the bicycle. As a result, it was shown that the bicycle vibration model had high reproducibility in the model development when actual road surface data were applied. Furthermore, as a result of building the road surface evaluation index of the bicycle version using this model, it became clear that the value reflected ride quality. In addition, since the frequency bands that affect ride quality differ between bicycles and cars, BRI, the road surface evaluation index of the built bicycle version, showed superiority over IRI.

 In recent years, the pavement industry has been actively examining efficient road maintenance using 3D point cloud data. In ICT paving works, construction quality is controlled with point cloud data acquired bya terrestrial laser scanner. However, an improvement of scanning efficiency has been required for the application of TLS into long distance. In addition, the practical use of point cloud data within a pavement service life has so far been inadequate. In this study, we invent a novel approach to the acquisition of point cloud data by a sensor fusion technology of a terrestrial laser scanner in combination with GNSS. This study also proposes a further application of point cloud data not only to the construction control stage but also to the management activities of a pavement.

 There are many case examples in tourist locations and shopping streets, where the pavement has various colours and textures. This helps to create attractive landscapes that visitors want to repeatedly visit. However, the adjustments of colours and textures alone cannot increase attractiveness for visitors. In order to have repeat visitors, there is a need for a design with a message. In order to approach this issue, we are trying to establish a method to engrave the pavement surface using road cutter to draw a gestalt image. In this method, it is necessary that the viewers are able to visually cognize the lines that make up the image. Therefore, we suggest measuring the visual distance of the observer from the fixed point, with a specified width of the engraved line. By finding out the distance, we will be able to design and plan effectively the size of the image to be created on the road. In order to evaluate the designed image in the planning process, the image is usually drawn onto the paper with ink in the actual size. We will also experiment to verify the validity of this method.

 The ballast track installed on a soft roadbed requires frequently repaired by tamping, so the roadbed improvement is desired. However, the roadbed improvement method that requires compaction of the roadbed material, execution is difficult in short working time at midnight. In order to shorten the execution time for roadbed improvement work, a method to fill the quick-hardening grout material into the voids of ballast which was used as aggregate for roadbed improvement layer was developed in the previous study. However, due to the passing of freight trains at night, its application was difficult in places where the working times is not sufficient. Therefore, in this research, in this research, in order to develop a new roadbed improvement method that can be executed in shorter working time, the roadbed improvement effect was evaluated from element tests and full-scale loading tests. Finally, the workability of the roadbed improvement was confirmed on the operating line.

 Ballasted track has the structure to lay the ballast under the sleeper. The ballast shows the plastic deformation behavior by cyclic train load gradually and we keep soundness of ballast to repair when its plastic deformation gets greater. It seems difficult to predict the deformation behavior of ballast subjected to cyclic train loading because its shape is granular, and then we can not predict the temporal change of deformation and select the weak point, needed to be repaired which has the vertical track regularity inspected by the track inspection.

 In this study, we aim to resolve and reproduce the deformation behavior of ballast subjected to cyclic loading, and considered to use the finite numerical analysis with subloading surface model as unconventional plasticity. We simulated the element test of ballast and the full scale model test of ballasted track on straight roads and considered the validity of the numerical analysis method.

 It is well known that there is a correlation between a dissipated work by FWD and a damage status of asphalt pavements. However, a dissipated work depends upon the total pavement structure including a base course and a subgrade. Therefore, the validity must be confirmed to evaluate the damage status of the asphalt layer using the dissipated work obtained by FWD. In this study, a dissipated work by FWD on the actual pavement and a dissipated work which can be obtained by the repeated compression/tension test of the core-sample taken from the pavement were compared and evaluated. As a result of the evaluation on those data, the high correlation was recognized between both dissipated works obtained by FWD and core-sample. The damage status of the asphalt layer can be estimated from FWD data.

 The 7 km section of CRCP was constructed on the Ban-etsu Expressway, which was opened in October 1990, in heavy snowy region of Northern Japan main island. The cracks had opened wide and the crack spacing had become narrow just after 9 year service, resulting in punch out on the surface. The deteriorated part of the CRCP section had been repaired with the partial depth patching using SFRC and asphalt overlaying. However, the similar severe deterioration has appeared on the other parts of the section recently. Therefore, in 2018, comprehensive investigations including material tests, excavation of the slabs and joints, FWD tests and electromagnetic radar survey were conducted to establish the rehabilitation strategy for the CRCP section. The investigations revealed that, since a large amount of salt solution is spread over the surface to prevent the frozen surface in winter, salt content was very high in cracked concrete slab and that most reinforcement bars were severely corroded there. The expansion of the corroded reinforcement causes and develops the horizontal cracks at the position of reinforcement bar. The thin upper layer of the cracked slab easily punch out due to traffic loads. This paper presents the results of the investigation and electromagnetic radar survey, then, discusses the mechanism of the horizontal cracking and possibility of prevention measures.

 Longitudinal crack of the asphalt pavement on the steel plate deck appears not only at the longitudinal rib or the main girder web, but also between longitudinal ribs, where the compressive strain due to the wheel load is dominant and thus crack has not been believed to occur. The mechanism of the longitudinal surface crack under the compressive strain has not been unveiled. In order to understand the viscoelastic behavior of the pavement on the steel plate deck and identify the causes of the crack, we conducted a viscoelastic analysis and calculated the viscoelastic stress and strain between longitudinal ribs under moving wheel load. As a result, it was found that compressive stress and tensile stress alternately develop between longitudinal ribs. Moreover, it was shown that this viscoelastic tensile stress is larger as the asphalt temperature is lower. Furthermore, the dissipation energy directly obtained from the result of the viscoelastic analysis indicates relatively large between longitudinal ribs suggesting the cause of longitudinal surface crack there.

 In order to manage huge stock pavement efficiently, it is important how to reduce "early deterioration section" where deterioration occurs earlier than the target year of service life. However, there are many parts that are not clear about the early deterioration mechanism of pavement, and it is difficult for the road administrator to take steps when the early deterioration occurs. Therefore, we conducted various structural investigations, such as open cut surveys, for one asphalt pavement that had actually deteriorated early. As a result, it was found that the stay of water and interlayer debonding in asphalt mixture layer can contribute to early deterioration. After that, we conducted core collection and FWD survey in multiple early deterioration sections. As a result, the stay of water and interlayer debonding in the asphalt mixture layer were confirmed similarly, and it was confirmed that these are one of the general factors of the early deterioration.

 We collected 48 samples of subgrade soil from a frost-heaved place of a national road in Hokkaido and investigated them for both frost susceptibility and geotechnical properties. We found that more than 80% of the subgrade soil samples taken at frost-heaved locations were coarse-grained, and many were of high quality suitable for compaction. An experiment of the variation in the fine fraction of such samples, however, revealed cases of marked variation over stretches of several hundred meters, raising concerns that differential frost heave could result in an uneven or bumpy roadway surface. None of the subgrade soil samples collected from the frost-heaved locations was judged to be non-frost susceptible. Most were instead judged to be frost susceptible, with many having high frost susceptibility. We examined several indices to determine their suitability as convenient measures of frost susceptibility and found that combination of ignition loss (a qualitative indicator of frost-heave susceptibility) and a fine fraction (a quantitative indicator of frost-heave susceptibility) was effective.

 The ground penetrating radar (GPR) surveys the overburden of underground pipe by interpreting the image, using the reflection from underground pipe and irradiating the electromagnetic wave from surface. The authors hit on the idea that put the iron plate on the underground pipe for the improvement of image interpretation. The experiments put the underground pipe were conducted in oder to clarify the influence of the iron plate and the overburden on the image interpretation. The measurement cases were the sixteeen cases, i.e., the two cases of the iron plate existence or not existence per the four cases of the overburden 1.0m, 0.8m, 0.6m and 0.2m, the two models of the GPR. As the results, the image interpretation became possible by putting the iron plate on the underground pipe in the image interpretation impossible condition. Furthermore, it was found that the relative error was 5.8%-7.8%.

 In the case of using natural ground as subgrade soil due to the restriction of road formation, complicated procedure of setting material model for pavement structure design is sometimes required in terms of physical conditions and sedimentary environment. Resilient modulus Mr is usually used for the evaluation of the deformation modulus as a design value in ordinary pavement design, but it is difficult to set a material model considering drainage conditions from the results of Mr-test carried out according to the standard of test method. For this reason, as an attempt to combine pavement engineering and geotechnical engineering, we developed a new testing method “CTX-BE test” by combining the cyclic triaxial test with the bender element test, the method of which are standardized by the Japanese Geotechnical Society. Based on a series of test results conducted on Toyoura sand, a new method for evaluate the deformation modulus and Poisson's ratio required for pavement structure analysis in consideration of drainage conditions of subgrade.

 Oil containing asphalts are applied to a test for separation of the asphalt into four fractions, FT-IR, and TG-DTA/MS to investigate discrimination method of the oil. The authors found TG-DTA/MS could indicate that some sort of oil was contained in the asphalt. But, information on what sort of hydrocarbons were contained in the asphalt was necessary to discriminate oils in asphalt. Pyro-GC/MS was additionally applied to evaluate hydrocarbons in oil containing asphalt. Total ion chromatogram indicated that machine oil containing asphalt generates peaks due to n-alkane and its isomer in 35~50 minutes of retention time and light oil generates peaks due to n-alkane whose carbon number is from 13 to 27.

 In order to repair asphalt pavement efficiently, it is necessary to properly evaluate the properties of existing asphalt pavement. Although there are many tests that directly evaluate the properties of existing asphalt pavement, it is extremely difficult to evaluate thin asphalt pavement properly such as a pavement on a bridge. For this reason, the authors have developed the cyclic torsional shear test in which the behavior of thin asphalt mixtures subjected to cyclic loading is properly examined. In this study, we clarified the influence on the test results when the loading condition, type of asphalt mixture, temperature and specimen thickness were respectively varied. We also proposed a method to correct the test results for a series of specimens having different heights.

 Asphaltenes interacted with resin components are dispersed in the oil component. When deterioration due to oxidation proceeds, these components form networks that disturb fluidity of asphalt binder. Asphaltenes have surface charges derived from their own functional groups, and the charge property of asphaltenes can affect the formation of asphaltene network. In this study, changes in charge property and coagulation-dispersion behavior of asphaltene due to deterioration were examined. The asphaltene of StAs coagulated at around pH4 and dispersed at high pH. Also, the zeta potential changed depending on pH. On the other hand, asphaltene of aged and recycled asphalt did not have significant coagulation state regardless of pH. The absolute values of the zeta potential of these asphaltenes were higher than that of StAs. It was suggested that this was caused by the increase of carbonyl functions due to degradation by oxidation.

 Examples of cases where road bridge RC slabs are damaged due to fatigue, salt damage, frost damage, ASR, etc. deterioration. Waterproof measures are important. Paving as well as waterproof layer has waterproofness. However, there are reports that the cause of damage is due to deterioration of pavement, cracks, etc.As a part of the research by the Public Works Research Institute, we investigated the water barrier performance of pavement constructed on the actual bridge, cause of pavement on the deterioration and damage of the deck. Based on the results, we clarified the cause of deterioration and damage on the deck slope and proposed proposal for contemplated dam damage

 In Japan, the sustainable quality of recycled asphalt mixture is desired. We previously reported that the effect of the differences of components of rejuvenator on the performance of the recycled asphalt and the mixture by carrying out the repeated recycling test. However, we need make great efforts and it take long time to do repeated recycling test, it is necessary to find methods to select appropriate rejuvenator for repeated recycled asphalt to simplify previous methods. In this study, it was recycled that the asphalt which has been degraded to about 5 penetration. The performances of the recycled asphalt of the low penetration asphalt and of the repeated recycled asphalt were compared. As a result, it was clarified that the recycled test using low penetration asphalt was available as the methods to select adequate rejuvenator for repeated recycling asphalt.