Roadway Sections Research Articles

할선탄성계수를 이용한 반복하중 하 지반의 영구변형 해석

Abstract The analysis of long-term performance of pavement sections under wheel loads is normally conducted in two separated steps. First the resilient behavior of the pavement is calculated assuming the pavement is a layered or discrete elastic medium, and then the permanent deformation is evaluated based on empirical permanent displacement equations. Material properties required in both steps can be obtained from cyclic triaxial tests, in other words, resilient and permanent deformation tests. While this analytical approach is simple and convenient, it does not consider the modulus degradation caused by cyclic loads, and some types of reinforcements such as geosynthetic cannot be modeled in this type of analysis. A model for degraded secant modulus is proposed and suggested to be used for the analysis of permanent behavior of unpaved roadway sections. The parameter for suggested model can be obtained from cyclic triaxial tests, regular practice in pavement engineering. Examples to estimate the model parameters are presented based on both laboratory permanent deformation test and large-scale plate load test.

Research on Eddy Air-Curtain Dust Controlled Flow Field in Hard Rock Mechanized Driving Face

The mathematical model of single-phase flow of gas was established based on the k-e two-equation model and numerically simulated the eddy air-curtain dust controlled flow field in hard rock mechanized driving face with the help of FLUENT software on account of the collocated grid SIMPLE algorithm. The result showed that, after all the pressure ventilation blown out by the radial clearance of mural cylinder, a full-face eddy air-curtain flow field is formed at the roadway section and with the help of the exhausting cylinder, it keeps pushing toward the tunneling place, forming the air-curtain dust controlled flow field that presses the tunneling place equally in front of the driver of road header. After the application of the development of new light polymer materials radial cylinder eddy air-curtain dust controlled system was adopted in hard rock mechanized driving face of north conveyor main roadway, the average settlement rate of total dust and repairable dust have reached to 97.4% and 96.8% respectively, reducing the local dust concentration effectively.

Comparative analysis of the transportation of select petrochemicals

Large volumes of hazardous cargo move across US roadways daily. Field counts are conducted on sections of roadway that provide aggregated volumes. A high level of interest exists in acquiring the capability to replicate these periodic field counts through a computer-simulated programme. Base data and computer simulation models were identified, which could be coordinated with field counts. The corridor traversing the core of Houston’s petrochemical industry served as the study area. Simulation data on producers and chemicals within the area were analysed, and alternate means of transportation were identified, to select chemicals most likely to be transported to the geographic area by truck. The likely frequency of shipments was calculated and compared to the field data. The study outcome reflected a good fit between the simulation and the field counts, providing positive conditions for application of the model to other corridors and showing strong potential for its predictive value.

Long-Term Performance of Pavement with High Recycled Asphalt Content

This paper summarizes the findings of several case studies on the long-term performance of recycled asphalt pavement (RAP). The goal of these studies was to provide the paving community with documentation on the long-term performance of roadway sections with a high amount of RAP compared with virgin sections on the basis of available information. Roadway sections that contained more than 20% RAP and that had been in place for at least 10 years were identified across the United States with the help of local agencies. The long-term performances of these various recycled sections were compared directly with mixtures made with similar virgin materials via measurements of distress criteria. These distress criteria included rutting, cracking, ride quality, and any overall performance rating that the local agencies used to evaluate their pavement sections. The virgin sections were placed in the same general location and time frame as the recycled sections. The sections with high RAP content, on average, tended to exhibit a lower ride quality, more cracking, and better rutting resistance than the virgin sections, but the differences were not always statistically significant. The differences between the performance ratings for RAP and virgin pavements were within 5% to 10%. Overall, pavement sections with a high RAP content performed at a level comparable to that of virgin sections in these case studies.

RWIS 설치를 위한 우선순위 선정 기법에 관한 연구

PURPOSES : This paper presents how to determine priorities of RWIS installation on national highways within the limited budget. METHODS : Analytical hierarchy process was employed to develop the entire methodology. In addition to this, various data such as vulnerable roadway section for snow removal, RWIS, AWS, AADT, and traffic accident were properly collected and analyzed for the future analysis. Then, GIS analysis was performed to find out the final candidate vulnerable roadway section for snow removal. In the end, expert survey was conducted to estimate weights for evaluation criteria. RESULTS : Results showed that metropolitan area has the most high priority, and Gangwon area, ChungCheung, and Honam in order. CONCLUSIONS : The main contribution of this paper is to suggest a logical methodology to prioritize RWIS installation within the limited budget, and thus snow removal operation during the winter season can improve in terms of getting more valuable information.

Parameter Optimization and Numerical Analysis of the Special Soft Coal Seam Roadway with Large Inclination Dip

Mechanized mining of Longwall top coal caving mining method was used in 1201 work face of thick soft coal seam in Du Jiacun Mine. The face is back to the wind drift along the seam floor excavation, transport drift along the seam roof boring the two crossheading basic fullcoal roadway, due to the relatively soft coal body, joints fractured, coal strength is low, and the coal-rock inclination, roadway section, the weakness of the surrounding rock rock, resulting in the excavation and support difficulties. This chapter based on numerical computation FLAC3D large-scale numerical analysis software, on the inclination special soft coal seam using a different roadway, support method, numerical simulation analysis of the support parameters, the contrast in different roadway support system support parameters, the deformation of surrounding rock displacement, stress distribution, the distribution of plastic zone, the big dip is extremely soft for Du Village coal mine mining Gateway support programs, and through on-site ground pressure observation of program verification.

Coupled Supporting of Rock Bolt and Anchor Cable in Large Cross-Section Roadway

With development of coal mining technology and equipment, the coal roadway section size increases gradually, making roadway more difficult to support. In the paper, the supporting of large cross-section roadway in Hedong mine is studied and roadway excavation supporting process is simulated by FLAC3D. Coal roadway deformation and the problem of original supporting scheme are analyzed including displacement field, stress filed and plastic zone. Several supporting optimizations are proposed combined with site investigation and simulation analysis. And the optimizations are simulated and calculated. By comprehensive comparison, the optimal supporting scheme is obtained and some supporting law in large cross-section roadway is concluded. These are helpful for supporting design in future.

Numerical Simulation of Eddy Air-Curtain Dust Controlled Flow Field in Hard Rock Mechanized Driving Face

The author established the mathematical model of single-phase flow of gas based on the k-ε two-equation model and numerically simulated the eddy air-curtain dust controlled flow field in hard rock mechanized driving face with the help of FLUENT software.The result showed that, after all the pressure ventilation blown out by the radial clearance of mural cylinder, a full-face eddy air-curtain flow field is formed at the roadway section, forming the air-curtain dust controlled flow field that presses the tunneling place equally in front of the driver of roadheader. After the application of the development of new light polymer materials radial cylinder eddy air-curtain dust controlled system was adopted in hard rock mechanized driving face of north conveyor main roadway, reducing the local dust concentration effectively.

A Task-Analytic Approach for Estimating Driver Task Demands on Specific Roadway Sections

Incorporating driver capabilities and information needs into roadway designs can be challenging because there is limited information available about the driving task in typical engineering design references. Task analyses of driving are one way to assist design and help consider driver needs. This article presents a new task-analytic method for estimating driver task demands along existing or planned roadway sections. A top-down approach was used to decompose driving maneuvers on a particular roadway section into segments, driving tasks, and information processing subtasks. Milestones were used to constrain task placement in space and time. Overlap between tasks over the same roadway section was used to identify regions of potentially heightened workload. Overall, this approach outlines a simple and structured method for accommodating driver tasks and information needs into the roadway design decision-making process.

Experimental study on supporting technology of gob-side entry with different roof conditions

Aiming to effectively solve the problem of deep mining with safety and high efficiency, according to geological conditions, production and stress analysis in roadway surrounding rock, experimental studies on roadway supporting of workface 103 under three types of roof conditions with different supporting technologies and parameters were carried out based on the theory of supporting technology of gob-side entry. The results show the supporting of gob-side entry retaining is successful, and the deep surrounding rock is effectively controlled by field monitoring and drilling-hole photos. After stress in surrounding rock of roadways restores stable, the final roadway deformation of surrounding rock of haulage roadway and air-roadway are both about 300 mm; width of gob-side entry is 3.8–4.0 m and average height is 2.0–2.2 m; roadway section is above 8.0 m2, which solves the problems of gob-side entry retaining support strength and safe mining; necessary conditions of mining safety in workface 103 are met.

The dynamic spatial multinomial probit model: analysis of land use change using parcel-level data

Many transportation-related behaviors involve multinomial discrete response in a temporal and spatial context. These include quality of paved roadway sections over time, evolution of land use at the parcel level, vehicle purchases by socially networked households, and mode choices by individuals residing across adjacent homes or neighborhoods. Such responses depend on various influential factors, and can have temporal and spatial dependence or autocorrelation. In many cases, dynamic spatial-model specifications based on maximum fitness, profit or utility may be most appropriate.This study develops a dynamic spatial multinomial probit (DSMNP) model by pivoting off the ordinary MNP model while incorporating spatial and temporal dependencies. The study adds value to existing work by addressing polytomous outcomes and space–time data. (Most spatial models rely on cross-sectional data sets and/or binary outcomes.) The paper first explains how the model reflects behaviors at play, and then describes estimation using Bayesian methods, which are of great interest in multiple fields. Simulated data sets containing both generic and alternative-specific explanatory variables are used to validate the model’s performance (and that of its associated code). Estimation efficiency issues and identification issues are discussed. The model is then applied to analyze parcel-level land use changes in Austin, Texas. It is found that better accessibility boosts the potential of residential development while hampering non-residential development. The effects of job and population density, neighborhood income and soil slope are also explored, and found to exert variable effects across space. It is also found that land development tends to cluster when existing development intensity in a neighborhood is low.

Driving experience and situation awareness in hazard detection

How does driving experience help in the development of situation awareness? A comparison of detection rates of roadway hazards that involved other road users by inexperienced and experienced car drivers and experienced motorcycle riders with car driving experience was conducted under laboratory conditions. Motorcycle rider-drivers, due to their greater breadth of road experiences, were predicted to have an advantage over other road users in the detection of hazards. Two types of hazards abrupt-onset events and gradual-onset hazards were examined. Abrupt-onset events capture attention by virtue of sudden movement and risk of impending collision, as when a pedestrian runs into the roadway for example. It was expected that these hazards would be detected regardless of experience or situation awareness. Gradual-onset hazards require the anticipation of unfolding events as recognition of the danger from children playing on the footpath, and as such are a test of advanced situation awareness. The results showed no inexperienced–experienced driver differences in the detection of either type of hazard, eliminating hazard-type as an explanation of previous inconsistencies. However, motorcycle rider-drivers detected gradual-onset hazards faster than car drivers and they also perceived more hazards in relatively safe sections of roadway, that is, they showed a higher level of situation awareness.

Application of Fuzzy Quantitative Theory for Crash Rate Prediction at Roadway Sections

A traffic crash prediction model was developed to accurately estimate roadway section safety. Crash rate of a roadway section was selected as the predicting measure. Moreover, the following seven factors were selected as major influencing factors: number of years of driving, number of lanes, radius of horizontal curves, longitudinal grade, road surface status, type of intersection, and width of road surface. The traffic crash prediction model was established based on fuzzy quantitative theory. To validate the model, crash data were collected at an actual site between 490.900km to 550.789km on a national highway. The result from the model was in agreement with the actual field data. The conclusion is that the model can be applied to other roadway locations.

Safety Effects of Icy-Curve Warning Systems

The California Department of Transportation (Caltrans) deployed an icy-curve warning system (ICWS) on a 5-mi section of SR-36 in Lassen County, California, over Fredonyer Pass. This section of roadway had a history as a high-crash location, with multiple fatal crashes. The vast majority of these accidents occurred when the pavement was icy, despite static signage that Caltrans had installed to increase motorist awareness. This study presents the results of research that investigated safety effects of the ICWS. An observational before–after study method with the empirical Bayes technique was used to determine the effects of ICWS on crash frequencies. The results showed that the ICWS reduced annual crashes by 18%. Moreover, analysis of ice-related accidents during winters found that the ICWS had reduced crash severities on this roadway section. On the basis of these results, a benefit analysis revealed that the ICWS provided an estimated monetary benefit of $1.7 million per winter season to motorists through reduced crashes. The study results are anticipated to contribute to a better understanding of safety effects of ice (or icy-curve) warning systems and increase the knowledge base of weather-specific treatments and their associated effects.

Louisiana's Experience with Open-Graded Friction Course Mixtures

The Louisiana Department of Transportation and Development (DOTD) began developing open-graded friction course (OGFC) mixtures in the late 1960s and early 1970s. Then, in the late 1980s, a moratorium was imposed on their use because of some early failure issues. However, OGFC mixture performance and service life have improved significantly since a new generation of OGFC mixture was promoted in the United States in the late 1990s. Inspired by the success of other state agencies, the Louisiana DOTD modified the earlier mix design and constructed four new OGFC sections during the past decade to evaluate pavement performance and safety benefits. This paper includes a comprehensive evaluation of Louisiana OGFC mixtures based on their laboratory and field performance. Laboratory work entailed material and mixture design in addition to numerous laboratory tests, namely permeability, draindown, tensile strength ratio, and loaded wheel test. Field evaluation involved visual inspection, pavement condition survey, skid resistance, and traffic safety. With few exceptions in the laboratory, the selected OGFC mixtures showed the potential to meet current Louisiana DOTD specifications, as well as various performance standards established by previous studies. The field analysis indicated that the OGFC test sections showed improved rutting, cracking, and skid performance when compared with typical Superpave® roadway sections. This performance evaluation will likely support the ongoing use of OGFC mixtures in the state of Louisiana. Additionally, the evaluation provides an opportunity to continually improve the current OGFC specification and mix design procedures adopted by the Louisiana DOTD.

Likelihood Parameterization of Bicycle Crash Injury Severities

This paper evaluates different factors and parameters contributing to likelihood of bicycle crash injury severity levels. Multinomial Logit (MNL) model was used to analyze impact of different roadway features, traffic characteristics and environmental conditions associated with bicycle crash injury severities. The multinomial model was used due to its flexibility in quantifying the effect of the independent variables for each injury severity categories. Model results showed that, severity of bicycle crashes increases with increase in vehicles per lane, number of lanes, bicyclist alcohol or drug use, routes with 35-45 mph posted speed limits, riding along curved or sloped road sections, when bicyclists approach or cross a signalized intersection, and at driveways. In addition, routes with a high percentage of trucks, roadway sections with curb and gutter, cloudy or foggy weather and obstructed vision were found to have high probability of severe injury. Segments with wider lanes, wide median and wide shoulders were found to have low likelihood of severe bicycle injury severities. Limited lighting locations was found to be associated with incapacitating injury and fatal crashes, indicating that insufficient visibility can potentially lead to severe crashes. Other findings are also presented in the paper.

Estimating Spatial Traffic States with Location-Based Data under Heterogeneous Conditions

Traffic data can be classified into spatial data and location-based data depending on the frame of measurement involved. Location-based traffic data pertain to information at a certain point, and spatial traffic data pertain to a longer section of the roadway. This larger coverage makes spatial traffic data better indicators of the traffic condition and the level of service of the roadway section. Therefore, spatial traffic data are preferred in any congestion mitigation program. Because the greater spatial coverage makes measurement of spatial traffic data more difficult than that of location-based data, the spatial data are usually estimated from other easily measurable location-based parameters. This paper proposes a methodology to estimate two of the most important spatial traffic parameters—density and space mean speed (SMS)—from the location-based parameters—flow and time mean speed (TMS)—under Indian traffic conditions. The estimation scheme was based on the Kalman filter and incorporated a dynamic macroscopic traffic flow model formulated in the state–space representation. This framework also included an empirical model calibrated with field data and a parameter α, which was used to relate SMS to TMS. The parameter estimation was formulated as an optimization problem, and the estimation scheme was corroborated with a comparison of density estimates with field data. Because the collection of SMS from the field was difficult, travel time collected from probe vehicle data was used as a surrogate measure to corroborate the SMS estimates. The results were promising and agreed well with the traffic behavior observed in the field.

Assessment of Interaction of Crash Occurrence, Mountainous Freeway Geometry, Real-Time Weather, and Traffic Data

This study investigated the effect of the interaction between roadway geometric features and real-time weather and traffic data on the occurrence of crashes on a mountainous freeway. The Bayesian logistic regression technique was used to link a total of 301 crash occurrences on I-70 in Colorado with the space mean speed collected in real time from an automatic vehicle identification (AVI) system and real-time weather and roadway geometry data. The results suggested that the inclusion of roadway geometrics and real-time weather with data from an AV I system in the context of active traffic management systems was essential, in particular with roadway sections characterized by mountainous terrain and adverse weather. The modeling results showed that the geometric factors were significant in the dry and the snowy seasons and that the likelihood of a crash could double during the snowy season because of the interaction between the pavement condition and steep grades. The 6-min average speed at the crash segment during the 6 to 12 min before the crash and the visibility 1 h before the crash were found to be significant during the dry season, whereas the logarithms of the coefficient of variation in speed at the crash segment during the 6 to 12 min before the crash, the visibility 1 h before the crash, as well as the precipitation 10 min before the crash were found to be significant during the snowy season. The results from the two models suggest that different active traffic management strategies should be in place during these two distinct seasons.

Estimating vehicle miles traveled combined with ITS data

‘Vehicle miles traveled’ (VMT) is an important performance measure for highway systems. Currently, VMT [or ‘annual average daily traffic’ (AADT)] is estimated from a combination of permanent counting stations and short-term counts done at specified locations as part of the Highway Performance Monitoring System (HPMS) mandated by the US Federal Highway Administration. However, on some roadway sections, Intelligent Transportation Systems (ITS) such as detectors and cameras also produce traffic data. The question addressed in this paper is whether and under what conditions ITS systems data could be used instead of HPMS short-term counts (called ‘coverage counts’)? This paper develops a methodology for determining a threshold number of missing daily traffic counts, or alternatively, the number of valid ITS data observations needed, in order to confidently replace the HPMS coverage counts with ITS data. Because ITS counts, coverage counts, and actual ground counts (e.g. continuous counts) cannot be found coexisting on a roadway section, it is hard to compare them directly. In this paper, the Monte Carlo simulation method is employed to generate synthetic ITS counts and coverage counts from a set of relatively complete traffic counts collected at a continuous count station. Comparisons are made between simulated ITS counts, coverage counts, and actual ground counts. The simulation results indicate that when there are<330 daily traffic counts missing in a set of ITS counts in a year, that is, when there are at least 35 days of valid data, ITS counts can be used to derive a better AADT than using coverage counts. This result is applied to calculate the VMT for the Hampton Roads region in Virginia. The comparison between the VMTs derived with using and not using the threshold number indicates that these two VMTs are significantly different.

Innovative Solutions for Sulphur in Qatar

Abstract The estimated sulphur output from Qatar is around 4 Mtpa by 2012, primarily from gas processing operations(Sulphur magazine, March/April 2009). Shell is using novel technologies to utilize sulphur in various applications such as concrete (Shell Thiocrete*), asphalt (Shell Thiopave*) and fertilizers (Shell Thiogro*). The sulphur utilization programme in Qatar Shell Research and Technology Centre is part of a global research and development effort to develop Shell's sulphur concrete and sulphur modified asphalt technologies, with particular emphasis on the needs of the Gulf region. Shell's innovative sulphur concrete technology has the potential to take sulphur concrete from use in niche applications such as chemical flooring to more mainstream applications such as garden products, road construction products (e.g. pavers and traffic barriers) and marine products. This is because the relatively low cost of the modification technology allows sulphur concrete to be considered in applications previously covered only by Portland cement. The first field trial of sulphur concrete in Qatar is a 16 square metre area of sulphur concrete tiles in the Pearl GTL Worker's Village, Ras Laffan Industrial City, Qatar, laid in May 2008. Laboratory results showed that the bending strength of all the sulphur concrete mixtures was greater than the strength of the cement concrete. Moreover, the water absorption of the sulphur concrete tiles was lower than that of the cement concrete tiles. Shell's sulphur-modified asphalt is a technology developed by Shell Sulphur Solutions in 2003, enabling a portion of the bitumen in an asphalt mix to be replaced by modified sulphur, resulting in a pavement that has enhanced mechanical properties such as increased stiffness and significantly reduced permanent deformation. A trial two-lane section of roadway of asphalt mix containing sections of Shell Thiopave and conventional asphalt mixture was constructed in October 2007 at Pearl GTL Worker's Village. The results of the field monitoring study showed that the total road section (sulphur-modified asphalt and conventional mixture) was free of any moderate or major distresses. Industrial hygiene monitoring during laying operations showed that SO2 and H2S emissions remain below the maximum limits when the temperature is controlled than 1450C.The laboratory characterization showed that the sulphur-modified asphalt mixture exhibited better resistance to permanent deformation and higher stiffness than the conventional mixture.