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The paper describes load and resistance factor design (LRFD) calibration for the resistance factor used in the Stiffness Method internal stability soil failure limit state for geogrid mechanically stabilized earth (MSE) walls. The Stiffness Method was recently adopted in the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications in the US, and will appear in the next edition of the Canadian Highway Bridge Design Code. The paper describes the details of the calibration of the soil failure limit state which is unique to the Stiffness Method. Calibration outcomes include consideration of the concept of level of understanding in the selection of nominal load and resistance values which is unique to LRFD foundation engineering practice in Canada. A practical conclusion from these calculations is that if product line-specific creep test data are available to estimate the reinforcement secant creep stiffness used for design, then a resistance factor of 1.0 is reasonable for US practice. If only minimum average roll value tensile strength data are available, then a value of 0.95 is recommended for US practice. For Canadian practice, the corresponding values for typical level of understanding are 0.90 and 0.85, respectively. [ABSTRACT FROM AUTHOR]

In the 1950s and 1960s, some Louisiana's bridges were constructed using steel twin-girder or truss systems, in which floorbeams are carried by the main members and continuous (spliced) stringers are supported by the floorbeams. The main members are either two-edge (fascia) girders or trusses. One of the byproducts of this type of design is that stringer bottom flanges are in compression in the negative moment region over the floorbeams, which could result in lateral torsional buckling (LTB) should inadequate lateral bracing be provided. When the continuous stringers are load-rated using AASHTOWare Bridge Rating analysis software (BrR 7.1), their LTB resistance is calculated in accordance with American Association of State Highway Officials (AASHTO) LRFD Bridge Design Specifications, which do not account for potential bracing provided by a noncomposite deck and could underestimate flexural strength. As a result, the rating may be low enough to require restrictive load posting or even bridge closure. This paper summarizes extensive experimental and numerical studies investigating the behavior of this type of floor system by testing two-span, continuous, steel stringers in a grillage that included three stringer lines, an interior transverse support (floorbeam), and transverse diaphragms at the end supports. The tests and finite-element analysis studies encompassed a variety of unbraced lengths and support conditions with steel diaphragms or timber ties acting as bracing members. The findings demonstrated that, for the systems examined, minimal bracing could substantially enhance LTB resistance and supported the use of higher flexural strengths than those currently predicted using AASHTO Specifications. This paper illustrates the use, challenges, and successes in LTB modeling beams with various support and bracing conditions. The most flexible cases were the most difficult to achieve close agreement with experimental results. [ABSTRACT FROM AUTHOR]

Prestressed girders often deteriorate over time due to environmental and man-made stressors, lowering the strength and serviceability of bridge structures. Although structural repairs are implemented to improve the load carrying capacity of the structure, the presence of numerous unknowns leads to high uncertainty in estimating the adequacy of repairs. For instance, the cross-section of the remaining strands, material properties, applied external loads, and workmanship assumptions made throughout the repair process introduce ambiguities when estimating the adequacy of the repairs. This study evaluates the efficiency of re-tensioning repairs of prestressed concrete bridge span girders. The repairs include field splicing, re-tensioning, of deteriorated or damaged strands by torquing a splicing coupler. The evaluation in this study considers component, system reliability, and load ratings while accounting for several uncertainties, such as structural repair, material properties, and external loads. This paper introduces an approach to account for prestressing strands damage and repair uncertainties while also accounting for other uncertainties. In this regard, five cases are studied: as-built, repaired, and three varying degrees of damage cases. First, the distribution for structural demand and capacity accounting for uncertainty in loads, material properties, and repair process is defined for each girder in the prestressed concrete bridge span. In doing so, Monte-Carlo simulation is employed to determine the distributions. Accordingly, the limit state function of the girders is defined from the obtained distributions. Then, the component reliability of each AASHTO (American Association of State Highway and Transportation Officials) Type II girder is calculated from the obtained reliability indices based on the determined limit state functions. Finally, a system reliability model of the span is developed from the component reliability of each girder. Some advantages and disadvantages of using component and system reliability index versus load rating in damaged and repaired prestressed concrete bridge girders are also discussed. Several critical conclusions are made regarding the uncertainties in structural repair, material properties and external loads, and their impact on the load rating and the component and system reliability of the prestressed concrete bridge structure girders. [ABSTRACT FROM AUTHOR]

Highly-skewed steel I-girder bridges are commonly used across the US, especially in congested areas, despite complications in their analysis and design. The American Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specification provides suggestions for design values of flange lateral bending stress in addition to line girder analysis when bridge skew exceeds 20° for certain cross-frame layouts. For bridges with skew exceeding 60°, a higher level of analysis is often required, with cross-frames considered primary members in design. Neither the magnitude of additional lateral stress nor the associated skew limits are particularly well understood, so more study is needed to refine and support this analysis and design approach. In addition to short-term response and load distribution, long-term bridge behavior for thermally induced stresses and deformations also needs to be more thoroughly studied. In support of an ongoing research initiative in Illinois, an agency survey was formulated and distributed across the US to understand practices used and challenges faced by state transportation agencies when designing and constructing skewed steel I-girder bridges. Findings from the responses of 23 state agencies illuminate issues, concerns, and current practice related to design, construction, and service life of those bridges. The agency survey informed selection of two bridges in Champaign, Illinois, for field monitoring, in order to provide new understanding of skew effects on bridge superstructure behavior. Three-dimensional finite-element analysis was conducted to guide field instrumentation planning, and initial measurements from the monitored bridges under traffic load confirmed good predictions compared to the planning-stage numerical study. This paper presents the initial stages of a long-term project that employs field monitoring and three-dimensional finite-element analysis of skewed steel I-girder bridges. Findings from a survey of state transportation agencies describe issues, concerns, and current practice related to design, construction, and service life of these bridges, which can be of interest to practicing engineers and contractors. This paper illustrates the integration of data from current practice and targeted numerical simulations to establish a rigorous basis for planning a bridge superstructure field monitoring campaign. The information and experiences summarized can be helpful to both practicing engineers and researchers. [ABSTRACT FROM AUTHOR]

In some instances, cast-in-place anchors need a little extra tension capacity in concrete breakout. One method of increasing capacity is to add a bearing plate at the embedded end of the anchor to increase the base area where the breakout cracking initiates. ACI 318-19 has a procedure for increasing the breakout area in Section 17.6.2.1.3. The American Association of State Highway and Transportation Officials (AASHTO) bridge code also has a procedure to design the bearing plates for post-tensioning anchors. These procedures have the same objective but yield different results. To effectively increase the breakout area, the bearing plate must be stiff enough to uniformly distribute the bearing stress to the concrete. This paper describes the analysis of previously published concrete breakout test data and the implications the tests have on determining if the bearing plate is rigid enough to uniformly distribute the bearing stress to the concrete. [ABSTRACT FROM AUTHOR]

Load testing of bridges is often used as a reliable method for assessing the capacity of in-service bridges with low analytical load rating factors. This paper presents a detailed load rating study of an 82-year-old concrete slab bridge with an unusually large aspect ratio of 3.73 by performing non-destructive diagnostic and proof load tests. The test-based modified rating factor is evaluated based on the American Association of State Highway and Transportation Officials (AASHTO) approach and the structural effective strip width approach which is then compared with the analytical rating factor from a simplified 1-D beam-line model. Field data is also used to evaluate the impact of the rotational stiffness of the bridge on its global response and load rating factor. The field test results based on the AASHTO approach reveal that the rating factor improves by up to 53% compared to the analytical rating factor. Monitoring the rotational residual response at the bridge supports is proven to be an effective method for assessing the global response of the bridge during field testing. The study shows that adding a rotational spring with a field-calibrated rotational stiffness to the 1-D analytical model of the bridge can significantly increase the load rating factor. [ABSTRACT FROM AUTHOR]

This paper presents a new tub girder series for Colorado, conforming to the articles of the American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications. Although the B618 tub girders developed by the Colorado Department of Transportation in the 1990s have been successfully used for decades, the need for an upgrade is essential to satisfy the requirements of contemporary bridge design and construction. After examining the performance of tub girders selected from six transportation agencies in the United States, an optimization algorithm was employed to generate efficient prototype sections. Then, detailed investigations were conducted to examine various practical aspects concerning the serviceability and ultimate limit states of AASHTO LRFD specifications. Parametric analysis with five bridge superstructures that accommodate up to four traffic lanes demonstrated the applicability of the prototype girders. A simplified version of the prototype sections was also delineated for regional precasters. Furthermore, a comparative study was carried out to evaluate the geometric stability and production costs of the prototype, simplified, and existing B618 girders. [ABSTRACT FROM AUTHOR]

This paper presents load factors for the residual capacity of highway bridges strengthened with carbon fiber-reinforced polymer (CFRP) composites. These load factors are intended to reflect structural loadings when a CFRP system malfunctions, so that a catastrophic event is prevented. To determine dead and live load factors under such an unordinary situation, stochastic inverse models are formulated per measure theory. Various bridge configurations and structural loadings are sampled from those used for calibrating the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (BDS). With an increase in span length over 18.3 m (60 ft), the dead load controls the response of the bridges relative to the live load. In accordance with inverse standard normal distributions, the live load effects are appropriate for representing service loadings (37.7% of the 75-year ultimate load effects, on average), which can thus be coupled with the residual capacity of the strengthened bridges. The most probable values are mathematically calculated to estimate the dead and live factors, and their influence is investigated on the moment and shear of the bridges. Analytical approaches, such as exceedance probability and safety index, substantiate that the calculated load factors outperform the load factors stipulated in a published design guideline. For the evaluation of residual capacity, the dead and live load factors are proposed to be 1.05 and 0.60, respectively. [ABSTRACT FROM AUTHOR]

This paper describes the characteristics of the new pavement design method developed by the American Association of State Highway and Transportation Officials (AASHTO), known as AASHTOWare Pavement-ME®, and presents the results of its application to the flexible pavement structures presented in the Portuguese Manual of Pavement Structures for the national road network. The results obtained clearly show that it is a very useful tool for road engineers not only for designing new pavement structures but also for the analysis of their performance and for efficiently planning maintenance and rehabilitation interventions. According to the characteristics of the case study that was considered, rutting is the most critical distress, since it presents values close to its threshold value of 20.0 mm, a value that is defined in Portuguese Quality Control Plans. [ABSTRACT FROM AUTHOR]

The focus of this paper is the development of improved live load distribution factor (LLDF) prediction equations for interior beams of press‐brake‐formed tub girder (PBFTG) bridges. PBFTGs consist of cold‐bent standard plate widths and thicknesses to form a trapezoidal box girder. Based on a survey of literature and field testing performed on PBFTG bridges across multiple states in the United States, the empirical equations found in the American Association of State Highway and Transportation Officials Load Resistance and Factor Design Bridge Design Specifications (AASHTO LRFD BDS) have been found to be conservatively applicable to shallow steel tub girder bridges. Improvements can be made to AASHTO LRFD BDS provisions relating to shallow steel tub girders and their respective live load distribution factors (LLDFs). To overcome this gap in design and analysis, rigorous three‐dimensional finite element analysis tools were developed and benchmarked against field implementations. The tools were used to analyze the live load distribution behavior of an interior girder of a matrix of approximately 18,000 PBFTG bridges. From the result of the analysis, statistical methods were employed to produce simplified empirical equations to better predict live load moment distribution in PBFTGs. The simplified equations are to be used in conjunction with line girder analysis to further simplify the design of shallow steel tub girder bridges and expand their application in the short‐span bridge market. [ABSTRACT FROM AUTHOR]

Drainage is one of the primary factors considered during the design of pavements. This paper presents the data from large-scale permeameter tests conducted on pavement sections to evaluate the drainage characteristic of geocomposite (GC) embedded subbase layers with and without traffic load. Two types of GCs with 2D core and 3D core were considered to enhance the drainage properties of a subbase layer. The large-scale permeameter test results indicate that the in-plane drainage capacity of the subbase layer improved by about 12 and 22 fold, respectively, for 2D−GC and 3D−GC. The GCs can drain infiltrated water at a rate of more than 300 m/day (in-plane permeability), even if the thickness of the subbase layer is reduced by about 50%. Over the pavement's design life, long-term in-plane permeability is estimated to decrease by 65–70%. It is estimated that the GC embedded subbase layers could drain off 50% of the infiltered water from a two-lane pavement system within 2 h, even after reducing the layer thickness by 100 mm. A set of new drainage coefficients for geocomposite improved subbase layers (m 3c) were proposed based on the American Association of State Highway and Transportation Officials drainage quality guidelines. • The study highlights the drainage characteristics of geocomposite-embedded subbase layers through a large-scale permeameter. • Even with a 50% reduction in the thickness, the geocomposite-embedded subbase layer could drain water at a rate > 300 m/day. • The in-plane permeability has decreased by about 20% under traffic loads. • A set of new drainage coefficients for geocomposite improved subbase layers (m 3c) were proposed. [ABSTRACT FROM AUTHOR]

Bridges are essential components of transportation systems and their unacceptable performance following a disaster may lead to disruption to relief operations. Many existing bridges all around the world were designed based on early editions of seismic codes and the performance of some old bridges following seismic events has revealed that they are seismically vulnerable. This paper provides a comparison of the seismic performance of reinforced concrete (RC) bridges designed according to recent code editions and according to earlier provisions. To this end, a probabilistic seismic safety assessment of RC bridges was conducted. Non-linear response history analyses were performed for each set of bridge samples subjected to earthquake ground motions with different severities employing three-dimensional models. The effect of the earthquake focal mechanism on the seismic vulnerability of the bridges was investigated. Moreover, fragility curves were developed for RC bridges designed according to the latest edition of the American Association of State Highway and Transportation Officials (Aashto) specifications (so-called new bridges) and those designed based on pre-1980 specifications (so-called old bridges). The fragility curves are presented in terms of the geometrical specifications of the bridges and the focal mechanism associated with input motions for both new and old bridges. [ABSTRACT FROM AUTHOR]

The current American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications' approximate formula for estimating long-term prestress losses is the outcome of the research work presented in National Cooperative Highway Research Program report 496. It is produced by simplifying the detailed method and taking into account the variability of concrete properties and the interaction between the precast concrete girder and cast-in-place deck. This paper presents two detailed parametric studies based on the average conditions for the design and construction of commonly used bridge girders. Three spans and, consequently, three levels of prestressing for each section have been considered. The first study establishes the creep multiplier Nc, whereas the second study evaluates the shrinkage multiplier Ns. Both multipliers are used in the lump-sum formulas for estimating long-term prestress losses for different bridge girders. The multipliers produced by these studies are compared with that of the current AASHTO LRFD specifications' approximate method, and new lump-sum formulas for long-term prestress losses are proposed. [ABSTRACT FROM AUTHOR]

Geotechnical data used for reliability-based design (RBD) and load and resistance factor design (LRFD) calibration can be parsed into subgroups based on material type, location, test method, and so on. Most often statistical analyses assume all data fall within a representative envelope, and pool (combine) all data into a single large data set without rigorously evaluating the veracity of this assumption. Adopting a Bayesian view, we introduce hierarchical/multilevel models as the more suitable alternative that takes into account multiple variation sources. Rather than assuming an identical parameter for data in all groups, hierarchical models assume exchangeable group-specific parameters, or informally, "similar but not identical" parameters. The utility of Bayesian hierarchical modelling is demonstrated by examining the accuracy of three reinforcement load models for polyester strap mechanically stabilised earth (MSE) walls and a simple hierarchical model as an example. We show that hierarchical models (i) have the customary complete pooling approach as their limiting case, (ii) quantify uncertainty from different sources of variation, (iii) prevent under-fitting, and (iv) can be used as tools for understanding the variations in the data. A simple RBD/LRFD example shows practical implications of hierarchical modelling of bias data. Finally, more complex/flexible hierarchical models are briefly discussed. Abbreviations: AASHTO: American Association of State Highway and Transportation Officials; ANOVA: analysis of variance; CDF: cumulative distribution function; CI: credible interval; COV coefficient of variation; DIC: deviance information criterion; LOGOIC: leave-one-group-out information criteria; LOOIC: leave-one-out information criteria; LM: load model; lppd: log pointwise predictive density; LRFD: load and resistance factor design; MCMC: Markov chain Monte Carlo; MSE: mechanically stabilised earth (wall); NHT: null hypothesis testing; PET: polyester; PGM: probabilistic graphical model; RBD: reliability-based design; WAIC: Watanabe-Akaike information criterion. [ABSTRACT FROM AUTHOR]

Owing to a severe shortage of natural aggregates in terms of quantity and quality, alternative aggregate resources must be utilized in civil engineering construction to meet significant increase in aggregate demand. This study focuses on manufacturing artificial aggregates for pavement applications using two waste materials- mine overburden waste from the coal mining industry and fly ash from thermal power plants. Liquid alkali activator, a mixture of sodium silicate and sodium hydroxide, is used as a binder. The centrifugal forces generated due to a rotating disc pelletizer enables mixing the said components resulting in formation of spherical-shaped pellets. The nucleated pellets are oven cured at 70°C for 7 days. Based on extensive laboratory test trials, the optimal features to produce competent aggregates in terms of angle and revolution speed of the disc pelletizer, dosage of the liquid alkali activator and the concentration of the NaOH are proposed. Finally, the manufactured aggregates are tested for properties relevant to flexible pavement applications. The aggregate impact and Los Angeles abrasion values are found to be 17% and 21.6%, indicating satisfactory resistance to impact and abrasion of aggregate particles under traffic loads. The basic material properties of these aggregates are found to conform to the Indian Roads Congress (IRC) and American Association of State Highway and Transportation Officials (AASHTO) standards for base and subbase layers. Moreover, base/subbase layers prepared with artificial aggregates and mine waste showed high California bearing ratio (CBR) of 54.3% and 80.5% for 2.5 mm and 5.0 mm penetration of the plunger, respectively, indicating high load-bearing capacity of pavement layers. [ABSTRACT FROM AUTHOR]

This study assessed soil pollution and index properties in Okpulor through geochemical, geotechnical, and geoenvironmental analyses. Twenty samples, comprising 14 surface and 6 shallow subsurface ones, underwent geochemical analysis for heavy metals (Fe, Cr, Cu, Zn, Ni, and Pb). Five geochemical indices, including the Geoaccumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF), Metal Pollution Index (MPI), and Potential Ecological Risk Index (PERI), were utilized. Simultaneously, six subsurface samples underwent geotechnical analysis for Natural Moisture, Grain Size, Specific Gravity, Bulk Density, and Atterberg Limits, following Unified Soil Classification System (USCS) and American Association of State Highway and Transportation Officials (AASHTO) guidelines. The Igeo highlighted significant heavy metal contamination in Okpulor soils, particularly Cd. EF values exceeding 1.5 underscored a strong anthropogenic influence, with CF indicating Cd's substantial contribution to overall contamination. PERI underscored the ecological risks associated with Cd contamination. Natural moisture content, ranging from 18.21% to 21.45%, indicated a notable presence of water in the soil during the dry season, potentially leading to increased leaching and migration of water-soluble contaminants. Bulk density values suggested moderate to lightly packed soils, impacting porosity and permeability, and influencing contaminant movement. Atterberg limits indicated low soil plasticity, impacting moisture retention and contaminant behaviour. Grain size analysis revealed poorly graded soils with a close sand-to-clay ratio, affecting water drainage. These geotechnical properties and heavy metal contamination reveal the intricate interplay between soil characteristics and contamination risks in the Okpulor area, emphasizing the need for targeted interventions to safeguard the environment. [ABSTRACT FROM AUTHOR]

The present work aims to assess earthquake-induced earth-retaining (ER) wall displacement. This study is on the dynamics analysis of various earth-retaining wall designs in hollow precast concrete panels, reinforcement concrete facing panels, and gravity-type earth-retaining walls. The finite element (FE) simulations utilized a 3D plane strain condition to model full-scale ER walls and numerous nonlinear dynamics analyses. The seismic performance of differentmodels, which includes reinforcement concrete panels and gravity-type and hollowprecast concrete ER walls, was simulated and examined using the FE approach. It also displays comparative studies such as stress distribution, deflection of the wall, acceleration across the wall height, lateral wall displacement, lateral wall pressure, and backfill plastic strain. Three components of the created ER walls were found throughout this research procedure. One is a granular reinforcement backfill, while the other is a wall-facing panel and base foundation. The dynamic response effects of varied earth-retaining walls have also been studied. It was discovered that the facing panel of the model significantly impacts the earthquake-induced displacement of ER walls. The proposed analytical model's validity has been evaluated and compared with the reinforcement concrete facing panels, gravity-type ER wall, scientifically available data, and American Association of State Highway and Transportation Officials (AASHTO) guidelines results based on FE simulation. The results of the observations indicate that the hollow prefabricated concrete ER wall is the most feasible option due to its lower displacement and high-stress distribution compared to the two types. The methodology and results of this study establish standards for future analogous investigations and professionals, particularly in light of the increasing computational capabilities of desktop computers. [ABSTRACT FROM AUTHOR]

To address the shortcomings of traditional prestressed concrete girders, a new hybrid beam element, the Hybrid Deck Bulb Tee (HDBT) is proposed. The HDBT utilizes staged fabrication. First, the bottom flange is cast with Ultra-high Performance Concrete (UHPC) and prestressed prior to casting the web and top flange with High-Performance Concrete (HPC). The purpose of this study is to analytically evaluate the structural performance of HDBT beams for bridge structures. Multiple HDBT bridges were designed following the state-of-the-art criteria in regard to UHPC bridge design. The performance was evaluated using the following criteria: 1) the deflections under live load and dead load, 2) design checks for temporary stresses before losses, 3) stresses at serviceability limit states after losses, and 4) demand-to-capacity ratios under the American Association of State Highway and Transportation Officials (AASHTO) Strength I load combination. To obtain more refined results for the serviceability limit state, the bridges were modeled using a commercial finite element software. The model captured the time dependent material properties such as strength gain, creep, and shrinkage, as well as the stages of fabrication. The analysis demonstrates that the innovative design and fabrication processes of HDBTs are capable of resolving the current limitations of prestressed concrete elements. [ABSTRACT FROM AUTHOR]

With the development of bridge crossings over rivers, the accident of the vessel–bridge collision is increasing as well. It is important to assess probability of bridges colliding with passing ships. Firstly, the AIS (Automatic identify system) data was collected and decoded to obtain the dynamic information of the ships passing the bridge including the distributions of ships position, speed, and yaw angle, which are then compared with the value recommended by the AASHTO (American Association of State Highway and Transportation Officials) specification. The mainly influential parameters of ship–bridge collision obtained from AIS data are used to correct the variables in the risk assessment of AASHTO specification, which intends to improve the assessment accuracy by considering the actual information of passing vessels. The collision probability with and without considering the actual situations of passing ships are compared. It is found that the distribution and transit path of passing ships significantly influence the collision probability. To improve the risk assessment accuracy, it is suggested to use the actual distributions of passing ships from AIS data. [ABSTRACT FROM AUTHOR]

E-ticketing was an intriguing technology to many state transportation agencies (STAs) pre-COVID-19 pandemic but gained significant attention upon arrival of the pandemic due to the contactless nature of the technology. Research completed prior to the pandemic into E-ticketing for asphalt paving primarily identified qualitative benefits and concerns. However, minimal academic literature exists in the postpandemic era discussing the additional E-ticketing benefits not previously captured which resulted in increased implementation by STAs. This research seeks to address this gap by gathering information from state members of the American Association of State Highway and Transportation Officials Committee on Construction (AASHTO COC), employees of the Kentucky Transportation Cabinet (KYTC), and members of the Kentucky Association of Highway Contractors (KAHC) and the Plantmix Asphalt Industry of Kentucky (PAIKY) regarding E-ticketing practices for asphalt paving in the postpandemic era. The first portion of the study combines national and state-level survey responses to create a qualitative benefit-cost analysis for E-ticketing for asphalt paving operations based upon experience gained through emergency implementation during the pandemic. To reinforce the results of the qualitative analysis and increase the power of the study, the second portion of the research creates a quantitative benefit-cost analysis (BCA) from data collected from KYTC construction projects to compare the traditional weigh ticket collection process with E-ticketing processes for both project engineers and inspectors. The analysis shows a statistically significant time savings for field employees but not project management personnel. The monetary analysis for Kentucky indicates that whereas E-ticketing does not result in significant time savings for all employees, there is substantial monetary benefit worthy of STAs adopting E-ticketing as policy. The primary contributions to the body of knowledge include an improved BCA methodology applied to a new domain of electronic bulk material tickets and an informed quantitative BCA framework useful for STAs as a proof-of-concept to champion E-ticketing implementation and by transportation-focused researchers for evaluating emerging technological applications. Previous research has focused on improving safety and task efficiency for field employees associated with asphalt paving operations. E-ticketing (electronic ticketing) has been proposed as an innovative technology to help augment typical tasks associated with asphalt paving. Before the COVID-19 pandemic, several state transportation agencies (STAs) had introduced pilot projects to study E-ticketing, but these yielded minimal policy adoption results. During the COVID-19 pandemic, many STAs pivoted to emergency usage of E-ticketing as the primary means of collecting information about asphalt material used on construction projects. This research compares previous qualitative analyses regarding the benefits and concerns associated with E-ticketing prior to the COVID-19 pandemic with lessons learned by STAs across the country after utilizing E-ticketing during the pandemic. Additionally, a case study focused on the Kentucky Transportation Cabinet (KYTC) is used to create a quantitative benefit-cost analysis from project-level data collected from various asphalt paving projects during the 2022 construction season. The findings indicate a statistically significant time savings for field employees utilizing E-ticketing and a benefit-cost ratio that promotes STAs adopting E-ticketing as a permanent policy. [ABSTRACT FROM AUTHOR]

The friction coefficient resulting from the road surface condition directly affects the vehicle braking condition and distance. In the American Association of State Highway and Transportation Officials (AASHTO), the braking distance for different speeds, upgrades, and downgrades is recommended. However, the effects of the variations in the friction coefficient, type, and weight of vehicles are not directly taken into account. Therefore, the present study firstly examines the effects of the variations in vehicle speed, friction coefficient, longitudinal grade (upgrade and downgrade) in AASHTO 2018, and the vehicle type on braking distance. Secondly, a nonlinear analytical approach is considered to estimate braking distance and determine a critical friction coefficient that causes decreases in the braking distance. The findings indicate that under dry road surface conditions (with a friction coefficient of 0.6), the weight of the vehicle predominantly influences braking distance, resulting in heavier vehicles having shorter braking distances than lighter vehicles across all selected grades, except at a − 6%. However, when the road surface friction coefficient decreases from 0.6 to 0.18, the impact of vehicle weight surpasses the effect of the longitudinal grade, leading to an increase in braking distance. Consequently, when designing a road, it's essential to consider not only the technical road parameters and vehicle dimensions but also the vehicle weight and the road surface conditions in areas prone to snowfall, among other factors. If we wish to account for snowy and icy conditions, in addition to AASHTO's classification of wet conditions, in order to refine predictions of braking distance, the results of this study can provide valuable insights for road designers. [ABSTRACT FROM AUTHOR]

Piles provide a convenient solution for heavy structures, where the foundation soil bearing capacity, or the tolerable settlement may be exceeded due to the applied loads. In cohesionless soils, the two frequently used pile installation methods are driving and drilling (or boring). This paper reviews the results of a large database of pile load tests of driven and drilled piles in cohesionless soils at various locations worldwide. The load test results are compared with the static analysis design method for single piles recommended in the Canadian Foundation Engineering Manual (CFEM) and other codes and standards such as the American Association of State Highway and Transportation Officials, Federal Highway Administration, American Petroleum Institute, Eurocode, and the Naval Facilities Engineering Command. An improved pile design procedure is proposed linking the pile design coefficients (β) and (N t) to the friction angle of the soil, rather than employing the generalized soil type grouping scheme previously used in the CFEM. This improvement included in the new version of the CFEM 2021 produces a more unified value of the pile capacity calculated by different designers, reducing the obtained design capacity discrepancies. [ABSTRACT FROM AUTHOR]

This study presents the use of V-M interaction diagrams to estimate the ultimate shear and moment demands of reinforced concrete (RC) beams. The method of analysis presented can be beneficial for both design and analysis as it provides a visual aid for gaining clearer insight into the determination of the maximum load-carrying capacity of a considered section, as well as its failure mode. To simplify the construction of such V-M interaction diagrams and remove the often-needed iterative procedure, the current American Association of State Highway and Transportation Officials (AASHTO) shear sectional design model based on the Modified Compression Field Theory (MCFT) was modified. As a result, the simplified process uses the strains of flexural reinforcement and moment demands at three events, which can be obtained by a simple elastic analysis. The maximum shear strengths were predicted for 1012 RC beams without transverse reinforcement using two current AASHTO shear design methods and the proposed simplified method. Overall predictions at failure from the V-M interaction diagram approach for all three methods showed great agreement with the test results with a reasonable coefficient of variation. Further investigation of the experimental variables revealed an overly conservative trend in beams with smaller effective depth and a/d ratio due to insufficient consideration of size effect and arch action. The noticeable trend by a/d ratio was somewhat moderated in the proposed method. Although the proposed method showed the most accurate predictions compared to the two AASHTO methods, an unconservative aspect existed for many cases so that a strength reduction factor of 0.75 was suggested. Also, the current strength reduction factor of 0.9 in AASHTO for shear was evaluated and considered appropriate. Given the satisfactory performance in estimating the maximum shear capacity, the proposed simplified AASHTO method using the V-M interaction diagram can serve as an alternative shear strength design and analysis method for slender RC beams. [ABSTRACT FROM AUTHOR]

Plastic waste (PW) constitutes a nuisance to our environment despite several efforts to reduce, reuse and recycle it. This study experimentally explores the possibility of storing plastic waste within a cement-stabilised soil that can be used as a road pavement layer material without adversely affecting the geotechnical characteristics of the stabilised soil. The soil is an A-2-6 soil, according to classification by the American Association of State Highway and Transportation Officials (AASHTO). Compaction characteristics, the California bearing ratio (CBR) and the unconfined compressive strength (UCS) of soil with 10% cement were determined for the 0, 2, 5, 10 and 15% addition of PW. The cementing of soil particles, which played a vital role in enhancing its strength on the addition of cement, may have been activated by the pozzolanic reaction between cement and soil particles. However, the addition of PW to this cement-stabilised mix led to a decrease in strength parameters at all variations. The soil with 10% cement and 2% PW yielded higher strength when compared to other mix ratios with PW and is suitable for use as a layer material in road pavement construction. As a sustainable strategy for PW management in developing nations, the usage of PW in cement-stabilised soil layer is recommended. [ABSTRACT FROM AUTHOR]

The practice of designing load-bearing walls with stabilized earth-based material is currently increasing in most developed countries. Potentialities of earth-based materials have room for more exploration, investigation, and promotion among building industry stakeholders globally. This research aims to analyze the compressive strength and durability of "Hamrah" Soil to assess its fitness in construction. Such a study is intended to get international and local (Saudi Arabia) construction practitioners' confidence about soil usage in the construction industry. To achieve this goal, sufficient soil material was procured from the Al-Hofuf region in eastern Saudi Arabia. Several geotechnical experiments were carried out to characterize and identify Hamrah Soil properties. The soil samples were classified in adherence to both the Unified Soil Classification System (USCS) and the American Association of State Highway and Transportation Officials (AASHTO) system. Stabilizing agents (cement and lime) were added at different percentages (0, 2.5, 5, 7.5, 10, 15% of the dry soil weight) to enhance their structural properties. Based on the acceptance criteria of 2 MPa strength, more than 5% cement maximized the stabilized rammed earth (SRE) sample strength more than 2 MPa (up to 6.3 MPa at 15% cement content), whereas 10% lime reached only1.46 MPa, which proved the efficiency of cement stabilization over lime. Micro-characterization techniques utilizing XRD, SEM, and durability tests also lent credence to the effectiveness of cement in the stabilization regime, giving more fibrous formations and a reduction in weight loss below the acceptable limits compared with the case of lime stabilization. [ABSTRACT FROM AUTHOR]

For most treated soils in compacted form for earth embankments, interest had been limited to the maximum stresses they can sustain before failure. This work studied the stress–strain behaviour of a compacted lateritic soil treated with palm kernel shell ash (PKSA) from 0 to 18% at 3% intervals, with a major focus on the critical-state characteristics (beyond the maximum stresses). The lateritic soil was characterised as A-2-6(0) in the American Association of State Highway and Transportation Officials rating and clayey sand (SC) in the Unified Soil Classification System. The PKSA was found to be pozzolanic. The British Standard light energy level of compaction and drained shear test were carried out on the treated soil. The optimum moisture content increased while the maximum dry density reduced with an increase in PKSA content. The PKSA of 0–18% content by weight of the dry soil improved the strength properties of the lateritic soil by 51·43%. The critical-state parameters (λ, Γ and M) of the soil mixtures were found to be in conformity with the usual range for untreated soils. [ABSTRACT FROM AUTHOR]

Currently, Egypt is using the [AASHTO, 1993. Guide for design of pavement structures. Washington, DC: American Association of State Highway and Transportation Officials] guide for the flexible pavement structural design. In this method the resilient modulus (MR) of the unbound granular base/subbase materials and subgrade soils is a measure of material stiffness used for characterisation. It is considered one of the major factors affecting the pavement layerthicknesses. However, in Egypt, California Bearing Ratio (CBR) is the main strength parameter used for characterisation of the unbound materials and subgrade soils due to its availability and simplicity. In this research, a comprehensive experimental testing programme was conducted on different unbound granular base/subbase materials typically used in pavement construction projects in Egypt. The testing programme includes MR, CBR, and basic material properties. The effect of aggregate gradation on MR is investigated. A model predicting MR as a function of the basic material properties is proposed. The MR–CBR relationship adopted in the current Egyptian Code of Practice is verified based on the testing results. The experimental data warranted the calibration of the current model. The calibrated model has reasonable goodness of fit statistics and yields rational MR estimates for the local materials. [ABSTRACT FROM AUTHOR]