Japan Road Research Articles

A comparative study of SPT-based liquefaction potential estimation methods from three sites in India

ABSTRACT In the present study, four different SPT-based methods for liquefaction assessment namely Seed and Idriss (S–I), Tokimatsu and Yoshimi (T–Y), Japan Road Association (JRA), and Chinese code for Seismic Design of Buildings (CSDB) method has been discussed in detail. The present study compares the liquefaction potential estimation of S–I, T–Y, and JRA methods, respectively. The S–I method predicts 9.29 and 3.42 times higher liquefaction occurrence compared to JRA and T–Y methods respectively. Different damage indices such as liquefaction potential index (LPI), liquefaction risk index (LRI), and ground settlement have been evaluated for an earthquake magnitude of 7.5 on the Richter scale and peak ground accelerations varying in the range of 0.1–0.36 g respectively. LRI provides a more precise estimation of the liquefaction damages compared to LPI. The gradation of liquefiable soil has been presented and compared with the established limits of liquefiable soils.

PROBABILISTIC MANAGEMENT OF PAVEMENT DEFECTS WITH IMAGE PROCESSING TECHNIQUES

Pavement management has traditionally relied on human-based decisions. In many countries, however, the pavement stock has recently increased, while the number of management experts has declined, posing the challenge of how to efficiently manage the larger stock with fewer resources. Compared to efficient computer-based techniques, human-based methods are more prone to errors that compromise analysis and decisions. This research built a robust probabilistic pavement management model with a safety metric output using inputs from image processing tested against the judgment of experts. The developed model optimized road pavement safety. The study explored image processing techniques considering the trade-off between processing cost and output accuracy, with annotation precision and intersection over union (IoU) set objectively. The empirical applicability of the model is shown for selected roads in Japan.

Fatigue durability of proposed vertical stiffener to deck connection details in orthotropic steel decks

Many fatigue cracks were reported at welded joints between vertical stiffeners and deck plates in orthotropic steel decks (OSDs) in Japan. These fatigue cracks were caused by restraining deck’s deflection by stiffeners. To prevent such cracks, reducing stiffness of stiffener top can be a solution. For newly fabricated OSDs, the Japan Road Association recommends cutting off the top of vertical stiffeners on cross beams. However, stiffeners with the gap have very little vertical load carrying capacity and it could not be applied to main girders. Half-circle notch method is retrofitting method for existing structures. For new OSD structures, it can be installed. Whereas a fillet detail is currently used for the beam-to-column connections of steel bridge frame piers to reduce stress concentration at right-angle corners of flanges. The fillet detail, which has not been considered for stiffeners, may be effective for new OSDs. In this study, fatigue durability of the half-circle notch detail and the fillet detail for new OSDs are evaluated through finite element analyses and fatigue tests using a full-scale specimen. As a result, the fillet detail showed superior fatigue durability without no fatigue cracks, while some fatigue cracks were developed in the half-circle notch detail.

Prediction of road traffic noise in the vicinity of trunk roads in Japan using digital road map platform

Prediction of road traffic noise in the vicinity of trunk roads in Japan using digital road map platform

Imperial Japan's Road to Total War 1868-1941: A Neoclassical Realist Interpretation of Systemic Pressures and Policy Responses

Imperial Japan's Road to Total War 1868-1941: A Neoclassical Realist Interpretation of Systemic Pressures and Policy Responses

A feature extraction and deep learning approach for network traffic volume prediction considering detector reliability

AbstractAccurate traffic volume prediction plays a crucial role in urban traffic control by relieving congestion through improved regulation of traffic volume. Network‐level traffic volume prediction and detector failure have rarely been considered in the literature. This paper proposes a framework based on long short‐term memory and the multilayer perceptron that can predict network‐level traffic volumes even with detector failure. A profile model learns the profile of the detector's signature (traffic pattern). Detectors with similar profiles are considered to have similar traffic patterns and are grouped into a cluster. Failed detectors can obtain reference information from similar detectors in the same cluster without additional information. A predictive model is developed for each cluster. The proposed method is validated using Japan Road Traffic Information Center data for three cities. The computational results indicate that the proposed method performs well both on typical days and atypical days (the COVID‐19 lockdown period and the 2021 Tokyo Olympics). Further, it considers detector reliability: the increase in mean absolute error is less than 1 veh/5 min when the probability of detector failure increases to 20%.

Modified ultimate bearing capacity formula of strip footing on sandy soils considering strength non-linearity depending on stress level

Most of the contemporary ultimate bearing capacity (UBC) formulas assume a linear yield function in shear stress-normal stress space. However, experimental investigations have corroborated the non-linearity in the failure envelopes of sandy soils. This study focused on the assessment of the stress level effect on the UBC of surface strip footings ascribed to the soil unit weight (γ), footing size (B), and uniform surcharge load (q). The rigid plastic finite element method (RPFEM) was employed for the analysis. The analysis method was validated against the centrifuge test results from the published references in the case of various sandy soils with different relative densities. The RPFEM, using the mean confining stress dependence property of Toyoura sand, is utilized in non-linear finite element analysis of model sandy soil. The normalized ground failure domains in the case of the non-linear shear strength model are gleaned smaller than those in the case of the linear shear strength one. The numerical results are compared with the guidelines of the Architectural Institute of Japan (AIJ) and the Japan Road Association (JRA). The modification coefficients are ascertained for the frictional bearing capacity factor (Nγ) and surcharge bearing capacity factor (Nq), and a modified UBC formula is proposed. The performance of the proposed UBC formula is examined against the analysis results and various prevailing UBC guidelines.

A numerical solution for seismic response prediction of bridge piers with high damping rubber bearings

The motion equation of a one-degree-of-freedom system when subjected to earthquakes is usually not solved by analytic methods. This problem can only be solved through the time step method, when integrating differential equations. This paper is devoted to presenting a numerical solution for a seismic analysis problem of a highway bridge pier with high damping rubber bearings under earthquakes. Based on time-stepping Newmark’s method, a numerical solution is developed to predict the seismic responses of the piers. The iteration Newton-Raphson method is also applied in the problem for static analysis of this nonlinear system. The ground acceleration in the analysis is the type- II earthquake in JRA 2004 (Japan Road Association). Further-more, high damping rubber bearings are modeled by the two models: the bilinear design model and the rheology model proposed by authors. After that, the stress responses and the displacement responses of the pier are obtained by a program that is implemented in Matlab software. The comparison results obtained from the two models show that the seismic responses of the pier strongly depend on the modeling of the rubber bearings. This is the important note for engineers to design the earthquake resistance of bridges with high damping rubber bearings. The solution is also a useful tool for engineers to predict the seismic responses of bridge piers in the design procedure.

Ambient Noise H / V Spectral Ratio in Site Effect Estimation in La Mesa de Macaracas, Panama

In the last 10 years, the community of La Mesa de Macaracas (central Panama) has experienced considerable aftershocks due to earthquakes of magnitudes up to 5.7 Mw. Although most of the community consists of single-storey houses, the agricultural development in the region has led to multistorey building projects. To determine whether the characteristics of the soils could affect future construction in the study area, 16 stations were established to measure ambient vibrations and estimate the predominant frequencies and their corresponding H / V ratio peaks through the ambient noise H / V spectral ratio technique. According to the site class established by the Japan Road Association, the results revealed the existence of (a) soft soil with a range of predominant frequencies between 0.7 and 1.6 Hz, (b) medium soil with a range of predominant frequencies between 2.1 and 2.4 Hz, and (c) hard soil with a range of predominant frequencies between 2.6 and 2.9 Hz. In the first type (soft), the resonance effect could affect constructions of between 6 and 14 storeys with H / V ratio peak values (amplification factor) in the range of 2.1 and 4.3, while in the second and third types (medium and hard soils), buildings of between 3 and 5 storeys could be affected, with H / V ratio peak values (1.5–2.0) except at the SS-9 station. These results were complemented with the V s 30 values obtained in four seismic soundings carried out at the site.

Site classification of seismic recording stations of Garhwal region of earthquake early warning system for Uttarakhand, India

Site classification is vital to carry out seismic hazard analysis of a region and get the damage patterns caused by earthquakes. In the present study, the ground motion of earthquakes recorded from 2015 to 2019 at 84 sites of the seismic network array of Earthquake Early Warning System for Uttarakhand are analyzed for site classification purposes. The predominant period from the mean horizontal to vertical spectral ratio curves was estimated. The classification schemes devised by Japan Road Association and National Earthquake Hazards Reduction Program are applied to classify the sites. Along with this, two other site classification indexes schemes are also applied for classification purposes. Data winnowing techniques are used over the ground motion records to pick out desirable quality records. Conclusively, the site class with the highest recurrence rate amongst the used methods is selected as the final class for that particular site. The effect of magnitude, distance and depth on horizontal to vertical spectral ratio are described and concluded that these factors do not significantly affect the ratio curves. The average horizontal to vertical spectral ratio curves obtained for all the sites matches well with the existing literature. The classification of a few sites are verified from the classification done by other methods in recent studies. It is evident from the results that the classification done in this study matches well with them.

Analysis on the impact of traffic safety measures on children’s gaze behavior and their safety awareness at residential road intersections in Japan

Traffic accidents involving child pedestrians, especially children under 12 years old, frequently occur at residential roads in Japan. The accidents are often caused by children with little walking experience not confirming their surroundings and jumping out on the streets. Therefore, to ensure the safety of child pedestrians, this study examined the effect of six safety measures, involving children’s gaze behavior while walking and consciousness of stopping at intersections on residential roads. The gaze measurement experiment and questionnaire survey were conducted on 84 first- to third-grade students. The results showed the usefulness of the footprint mark through the analysis on the child's gaze behavior and consciousness of stopping when walking. The present study clarified that by installing the footprint mark, it is possible to call attention to intersections earlier and increase the feeling of consciousness to stop when they face an intersection. In contrast, color pavement at intersections, which is an effective measure to alert the driver, was not very effective in this study. This suggests that drivers and pedestrians, or adults and children, may have different effects even if the same measures are taken. Thus, traffic safety measures on the roads need to consider the various attributes of road users.

Development of rocking isolation bearing system (RIBS) to control excessive seismic responses of bridge structures

AbstractRocking structures are recognized as an effective seismic response modification technique due to their peculiar dynamic characteristics. Meanwhile, in bridge structures, strong ground motions have frequently caused a rocking motion of pin bearings around their two toes, resulting in the pulling‐out of anchor bolts. This study, motivated by the promising features of rocking behaviors, seeks to develop a rocking isolation bearing system (RIBS) to control excessive response in bridges. An example bridge featuring such a RIBS, consisting of the pin bearings removing anchor bolts to release the rocking motion, the girder type superstructure, and an array of bridge piers, is characterized by a simplified model. Two coefficients of restitution (COR) models are used to investigate the effects of energy dissipation during impact: the Housner model, and a model which simultaneously modifies the velocities of the superstructure and substructures. The dynamic characteristics of RIBS and its control effectiveness on the bridge structure are discussed through a series of dynamic analyses, under both observed ground motions and the design ground motions specified in the Japan Road Association (JRA) design specifications for highway bridges. The simulation results demonstrate that the seismic performance of the bridge structure can be substantially improved, with decreased pier displacement at an allowable bearing rotation level.

Factors Influencing Fatalities or Severe Injuries to Pedestrians Lying on the Road in Japan: Nationwide Police Database Study.

To help reduce the number of pedestrians lying on the road suffering fatal or severe injuries as a result of vehicle collisions, we investigated the influencing factors. We conducted an analysis of the records of the Institute for Traffic Accident Research and Data Analysis Japan between 2012 and 2018; we found that 2452 pedestrians lying on the road were involved in collisions (797 fatalities, 784 severely injured, 871 mildly injured). Multivariate logistic regression analysis identified the following as major factors that positively influenced the fatalities: head or neck injuries (odds ratio [OR], 90.221); trunk injuries (OR, 71.040); trucks as offending vehicle (OR, 2.741); collision velocity of 10–20 km/h (OR, 31.794), 20–30 km/h (OR, 2.982), 30–40 km/h (OR, 8.394), 40–50 km/h (OR, 16.831), and >50 km/h (OR, 18.639); and hit-and-run cases (OR, 1.967). The following had a positive influence on severe injuries: trunk injuries (OR, 4.060); collision velocity of 10–20 km/h (OR, 2.540), 20–30 km/h (OR, 3.700), 30–40 km/h (OR, 5.297), 40–50 km/h (OR, 5.719), and ≥50 km/h (OR, 5.244); and hit-and-run cases (OR, 2.628). Decreasing the collision velocity, avoiding collisions to the head and neck or trunk, and preventing hit-and-run cases would be effective in reducing fatal or severe injuries to pedestrians lying on the road.

Bicycle lane planning: A site appraisal in Fukuoka, Japan

Cycling is one of the most sustainable modes to commute from one place to another. However, not everyone views bicycles as a fundamental component of the overall transportation system because presently, societies are heavily reliant on private vehicles. In reality, most see it only as a tool for recreational and exercise purposes. This paper seeks to identify the planning and design of bicycle lanes in Fukuoka, Japan. The research applies the site appraisal technique which involves gathering information about comparable site values within four areas i) Hakata station, ii) Ohori Park and Nishi Park, iii) Island city and iv) Fukuoka residential area. The findings identified various policies, guidelines and designs for bicycle infrastructure in Japan. There are significant differences between bicycle road, bicycle lane and sidewalks in Japan and Malaysia. Some of the findings show that Japan is gearing towards an even more bicycle friendly environment with the promulgation of the Promotion of Bicycle Use Act. However, there are also some setbacks such as the ineffectiveness of colored lanes to differentiate between bicycle lanes and pedestrian or vehicle lanes. Malaysia needs a blueprint and guidelines at the state and local levels to designate bicycle lanes and guarantee users’ safety and enjoyment. A specific unit for cycling in transportation related agencies is proposed to make Malaysia a bicycle-friendly city. Keywords: Bicycle, bicycle lane planning, Fukuoka, Japan

Road traffic noise mapping based on aerial photographs - sound power level determination of road vehicles

As the first step to obtain a city urban area noise map of road traffic noise, sound power levels of vehicles on the roads should be accurately estimated over a wide area. In Japan, ASJ RTN-Model 2018 was proposed as the representative road traffic noise prediction model, and by using the model sound power level of a vehicle can be determined if the vehicle type, traveling speed, and driving mode are known. As such data on urban road network, the Ministry of Land, Infrastructure and Transport of Japan publishes the road traffic census including road traffic volume and travel speed of major roads in Japan. The data, however, is limited to major roads and there is no data on minor roads. In this study, to estimate noise condition and situation on arbitrary road, a method for estimating the traveling speed and the traffic volume of vehicles on the road from aerial photographs was examined. Road traffic noise levels along several roads in Tokyo were analyzed by the proposed method and the validity of the calculation results were verified by comparing with short-time measurement results obtained along the target roads.

Unseating of single-span bridges with skew angles out of the limit range for free rotation

Past researches have indicated that skewed bridges can rotate around the obtuse corners upon gap closure and the bridge deck can rotate freely when the skew angle is within a limit range. Beyond this range, the rotation of the bridge deck could be locked against the abutments. For these bridges, girder unseating can be avoided either by geometric constraint of the deck or by providing adequate support length to account for seismic demands. In this paper, the unseating of single-span bridges is studied for skew angles out of the limit range for free rotation. To begin, the skew angle limit range for free rotation was derived for bridges with and without expansion gaps. It was found that the expansion gap has a slight influence on the skew angle limit range for free rotation. The minimum support length (N) of skewed bridges to reach geometric constraint (when locked against the abutments) was then derived step-by-step based on geometry. It is found that the N to reach geometric constraint increases with skew angles approximately in an exponential manner. Finally, a parametric study was performed on prototype skewed bridges using a shake table experiment-validated nonlinear model to compute the support length demands during design-level earthquakes. Nonlinear analysis was performed under seven historical near-fault records scaled to the design-level earthquakes. Comparison was made between the support length to reach geometric constraint and those from numerical analysis. The results indicate that it is very likely that a single-span bridge of any skew angle could rotate freely during the design-level earthquakes even when its geometry could allow it to be blocked by the abutments. Therefore, the minimum support length of single-span bridges should be designed based on seismic demands rather than geometric constraint when the skew angles are out of the limit range. In addition, it was also found that the Japan Road Association (JRA) is unreasonable to assume zero skew effect on the minimum support length requirements and current codes and specifications underestimate the skew factor when the skew angles fall out of the limit range.

A Hybrid Method to Evaluate Soil Liquefaction Potential of Seabed at Offshore Wind Farm in Taiwan

This paper undertakes liquefaction analysis with simplified procedures with standard penetration test (SPT) data and cone penetration test (CPT) data obtained from an offshore wind farm in the Changhua area. The soil liquefaction resistance calculated by the SPT-based simplified procedure suggested by the Japan Railway Association was in agreement with the laboratory results. The CPT is widely used in the site investigation of offshore wind farms. However, Taiwan’s registered professional engineers are still familiar with soil liquefaction analysis for offshore wind farms using SPT-based methods. Hence, a hybrid method that incorporates an SPT–CPT correlation into the New Japan Road Association (NJRA) method is proposed to evaluate the soil liquefaction potential for offshore wind farms in Taiwan. In the case studies of soil liquefaction with five groups of adjacent boreholes in Changhua’s offshore wind farms, the hybrid method shows that the soil liquefaction potential with CPT data is consistent with the results calculated with SPT-based simplified procedures. To quantify the risk of soil liquefaction, Monte Carlo simulation is used to calculate the uncertainty of CPT–qc for estimating the probability of soil liquefaction with the hybrid method.

Network theory-based accident scenario analysis for hazardous material transport: A case study of liquefied petroleum gas transport in Japan

ABSTRACT To analyze an accident scenario involving the transport of hazardous material (HAZMAT), a complex accident process must be completely described; however, existing analytical approaches, which are influenced by the arbitrariness of a given analyst, may not cover the entire process. Thus, the aim of this study is to develop a new approach for analyzing accident scenarios associated with HAZMAT transport, using network theory as a key to illustrate the complex accident process. In the developed approach, accident scenarios are sampled from the accident processes by fusing the HAZMAT transport accident network and transport environmental factors, based on accident data. The proposed approach was applied to a case of Liquefied petroleum gas (LPG) transport by road in Japan. The case study identified 68,874 scenarios and classified the identified scenarios into three types of risk categories: 80 high-risk, 9,112 medium-risk, and 59,682 low-risk scenarios. It was observed that the scenarios identified could successfully help understand the complex accident processes in HAZMAT transport and incorporate the safety measures through the accident network. The proposed approach for accident scenario analysis can accelerate the risk assessment of HAZMAT transport and help advance risk assessment to risk management.

Assessment on liquefaction potential of seabed soil in Chang-Bin Offshore wind farm considering parametric uncertainty of standard penetration tests

Liquefaction potential analysis is a required task in the foundation design process of offshore wind turbine in Taiwan. The standard penetration test (SPT) is mostly used in the preliminary soil investigation of the pilot offshore wind farm in Chang-Bin, Taiwan. Due to the different experimental conditions and operating conditions, the N value (SPT-N) of SPT varies greatly. This study applies statistical methods in conjunction with the New Japan Road Association simplified-empirical method (NJRA method) to incorporate the uncertainty of SPT-N values into the offshore liquefaction potential assessment to quantify the risk of seabed liquefaction. The study statistics the field experimental geotechnical parameters SPT-N and determines the probability density function of the SPT-N distribution of each layer of soil in the offshore wind farm. In order to quantify the risk of seabed soil liquefaction potential, the Monte Carlo random sampling method is used, and by the NJRA method to carry out the seabed liquefaction potential in Changhua, Taiwan. After comparing, the results obtained by the current SPT-based soil liquefaction potential assessment by deterministic approach are conservative. In the ground investigation of offshore wind farm development, the method proposed in this paper can access the thickness of liquefiable soil layers under any given probability for optimizing offshore wind turbine foundation design.

Experimental study on time-dependent deformation of hybrid steel–PRC girder with headed stud shear connections under sustained loading

In a hybrid girder, the connections at the steel–prestressed reinforced concrete (steel–PRC) junction must be designed to resist steel–concrete interfacial tensile and shear forces. Headed stud shear connections are most commonly and widely used for such an application. In Japan, the Japan Road Association specifies a stud capacity that is 0.12, 0.13, and 0.22 times those of the American Institute of Steel Construction, Japan Society of Civil Engineers, and EURO code specifications, respectively. Hence, in Japan, the existing design method uses less than 50% of the actual nominal shear capacity of connectors. Owing to a low design shear force, the influence of sustained loads has not yet been considered nor studied comprehensively. Moreover, in a hybrid girder, the prediction of the time-dependent deformation behaviour under sustained loading is crucial for ensuring serviceability; however, few studies have focused on this subject. Five scaled-down hybrid steel–PRC girder specimens of a real bridge with headed stud connections were tested under sustained and static loads. The time-dependent deformation behaviour was sensitive to the exposure time, previous loading history, prestress level, concrete strength, and creep and shrinkage phenomena. The results of this study provide an important basis and reference data for designing such girders while considering their long-term response with time effects.