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Automated vehicles equipped with adaptive cruise control systems (ACC-AVs) are prevalent and the ensuing issue is the feasibility of ACC-AVs' operation on the roads. This study investigates the feasibility of road horizontal curve designs for ACC-AVs from a vehicle dynamics perspective. Following the scenario generation framework, we created and tested several scenarios featuring horizontal geometric elements and design speeds, conducting a safety evaluation based on the critical adhesion coefficient, lateral acceleration, lateral-load transfer rate, together with driving comfort indicators. Results indicate that ACC-AV can navigate on road curves designed with a common minimum radius (Rmin_com) effectively at speeds over 60 km/h , comparable to conventional vehicles. However, both Rmin_com and limited minimum radius (Rmin_lim) designs show limitations. Additionally, the feasible radius ranges for ACC-AV reveal the capability to safely handle sharper curves and maintain higher speeds, suggesting potential for adaptable road design in complex environments. Finally, minimum radius ranges were summarized for ACC-AV safe and comfortable operation on road curves, unveiling the potential risks and reminding designers in curve design controls for ACC-AVs. [ABSTRACT FROM AUTHOR]

The Arkansas Department of Transportation (ARDOT) Maintenance Division is concerned about the use of certain aggregates in asphalt mixture because of their durability and performance issues. Good performance of the pavements can be ensured by selecting good-quality aggregates along with asphalt binders that can produce compatible aggregate–binder systems. The primary goal of this research was to determine proper asphalt binders and aggregates for the construction of highways in Arkansas. Three performance grade (PG) asphalt binders, namely PG 64-22, PG 70-22, and PG 76-22, prepared from two different crude sources, were investigated. This study also included four types of ARDOT-commissioned aggregates, namely gravel, sandstone, limestone, and dolomite, from four quarries throughout Arkansas. Selected properties of asphalt binders and aggregates (e.g., physical, mechanical, and chemical) were evaluated by performing a series of routine laboratory tests. To evaluate the performance of the asphalt mixtures, work of cohesion, work of adhesion, and boiling resistance tests were conducted. These aggregates, binders, and aggregate–binder systems were ranked based on the properties obtained from laboratory tests. In general, any combination of dolomite or limestone with a stiffer binder such as PG 76-22 or PG 70-22 is expected to be superior to an asphalt mixture with either sandstone or gravel. The outcomes of this research will help highway agencies and pavement professionals in selecting suitable asphalt binders and aggregates for long-lasting pavement construction. [ABSTRACT FROM AUTHOR]

Design guidelines for freeway ramp entrances are based on speed and acceleration data collected before 1950. This study investigated driver behavior over the entire freeway entrance area, including the ramp, the acceleration speed-change lane (SCL), and the freeway right lane (FRL). Video-based trajectory and speed profile data were collected using unmanned aerial vehicles (UAVs) and were used for qualitative and quantitative analysis. General trends of the relationships between driver behavior measures and geometric characteristics of entrance ramp terminals were investigated under different traffic and design conditions. Results showed that vehicles tended to merge onto the freeway at relatively low speeds such that the difference between their mean speed at merging and that of FRL vehicles was statistically significant. Results also confirmed that SCL drivers tended to start acceleration after they passed the middle of the ramp controlling curve. Regression models were developed for predicting driver-vehicle behavior on SCLs and on-ramp curves using traditional regression for each parameter separately and simultaneous modeling using structural equation modeling. An example application is presented to demonstrate the use of the developed models in reliability analysis of entrance ramps, which can be used to establish probabilistic road design guidelines. [ABSTRACT FROM AUTHOR]

This study focuses on investigating the relationship between binder chemical composition, microstructure development in alkali-activated paste (AAP), and the sulfuric acid resistance of alkali-activated concrete (AAC). Experimental analyses, including x-ray diffraction, thermogravimetric, and scanning electron microscopy (SEM) tests, were performed on the AAP to understand the impact of critical chemical compositions on the formation of hydrotalcite, portlandite, CSH, and CASH during the alkali-activation process. The sulfuric acid resistance of AAC was evaluated through various tests, including compressive strength, porosity, chemical titration analysis, and weight loss tests. These tests aimed to assess the ability of AAC to withstand sulfuric acid attacks and investigate how the binder's chemical composition influenced its resistance to acid exposure. The results revealed that higher alumino-silicate ratios (Al/Si) and magnesium oxide (MgO) content in the binder composition led to increased amounts of hydrotalcite and CASH in the alkali-activated system when zeolite and metakaolin were used as replacement materials for slag. The AAC specimens with slag and metakaolin showed lower porosity at the same replacement ratio. The increased amounts of hydrotalcite and CASH in the AAC microstructure contributed to a reduction in the concentration of sulfate ions penetrating the AAC, leading to improved sulfuric acid resistance. This information can contribute to optimizing binder formulations for improving AAC's mechanical properties and durability in corrosive environments. Practical Applications: Concrete samples containing metakaolin and synthetic zeolite tested throughout this research project can be utilized in different construction and civil engineering applications, all with differing degrees of suitability. Metakaolin and synthetic zeolites can be used as a slag replacement in concrete samples and used in masonry bricks, commonly used in masonry walls, columns, and partitions. Furthermore, load-bearing or nonload-bearing masonry structures for building and civil engineering can also adopt the incorporation of AAC. Metakaolin and synthetic zeolite types utilized in this research project could also be applied to produce slag granular mixtures for use in the construction of roads and airfields. The requirements for the relevant constituents, composition and laboratory performance classification are specified in BS EN 12390-1:2019. [ABSTRACT FROM AUTHOR]

The secondary utilization of iron tailings solid waste meets the green development requirements of road construction in the new era. Currently, there is a lack of research on the equivalent confining pressure effect of fiber, the influence of complex stress paths on the mechanical properties of modified soil, and the internal damage in soil based on energy dissipation theory. The effects of different polypropylene fiber content, confining pressure, curing age, and complex stress path on the mechanical properties of fiber cement–modified iron tailings (FCIT) were investigated by triaxial tests and energy angle. Combined with the actual subgrade engineering, the stress path test is set up, and the strength index of the FCIT under different working conditions is obtained. From the thermodynamic point of view, the failure process for the FCIT is further revealed. The results show that: (1) the optimal fiber content of FCITs is 0.75%. At this time, the mechanical properties of FCIT are optimal, the strength is high, and shear failure is not easy. The fiber has the equivalent confining pressure effect, which could provide better shear performance for FCITs so that the FCIT is resistant to collapse in embankment construction; (2) the influence of multislope stress path on the secant modulus of the FCIT is worse than that of a single-slope stress path. The influence of curing age on the secant modulus of these two kinds of stress path is consistent, and the secant modulus of the FCIT at 28-day curing is 1.2 times that at 7-day curing; (3) after 7 and 28-day curing, the dissipation energy of the FCIT was consistent when the fiber content was 1%. Due to the equivalent confining pressure of the fiber, the fiber dissipation energy of the FCIT is not affected by the curing age. The total dissipated energy of the FCIT with a stress path slope of 1.5 is 5–6 times that with a stress path slope of 2.5. The total dissipated energy of the single-slope and multislope stress paths decreases with the increase in curing age. [ABSTRACT FROM AUTHOR]

Glass fiber–reinforced polymer (GFRP) reinforcements can be used as shear friction connectors at the interface of concrete composite elements to maintain structural integrity. However, the shear friction mechanism at the interface greatly depends on the interface condition and the stiffness of the reinforcement crossing the interface plane. A total of 18 GFRP-reinforced concrete (RC) push-off specimens were constructed and tested until failure under monotonic load. The test parameters included the shear plane condition (roughened or not roughened, cold joints and monolithic), type (steel and GFRP), and ratio (0.24%–0.47%) of reinforcement crossing the shear plane. Roughening the interface had a little effect on the overall behavior and shear capacity of the specimen. Conversely, the monolithic specimens carried approximately 60% higher load than their cold-joint counterparts; nevertheless, the failure was more brittle. The capacity prediction by the Canadian Highway Bridge Design Code showed conservative results. By contrast, the predictions of the American Concrete Institute's model for steel-RC elements overestimated the test results for cold-joint and monolithic specimens with reinforcement ratios of 0.43% or higher. [ABSTRACT FROM AUTHOR]

A large amount of excavation waste soil will be produced during highway construction, which will lead to environmental pollution and construction site occupation. To make full use of the excavation waste soil, hydraulic pile-forming equipment with a maximum pressure of 200 t is developed based on the principle of building clean transportation infrastructure. In addition, a precast pile with modified waste soil (PPMS) is proposed to achieve the large-scale consumption of the excavation waste soil. The PPMS has the advantages of regular shape, reliable quality, and stable bearing capacity. The relevant production standards and construction processes are proposed in this paper. The static pressure test analysis of the PPMS and lime–soil compaction pile was performed to verify the feasibility of the PPMS in reinforcing soft foundations. The test results show that the bearing capacity of a single PPMS could reach 600 kN. Under the upper load of 400 kPa, the settlement of the PPMS-reinforced soft foundation is 30% smaller than that of the lime–soil compaction pile. The PPMS has the advantages of high bearing capacity and economic and environmental protection, which is suitable for reinforcing soft foundations. [ABSTRACT FROM AUTHOR]

Road and highway construction projects are often a concern among surrounding communities as these projects possess significant risks to the environment, and their impacts can reach far beyond the project areas. Monitoring the environmental management plan (EMP) implementation of road and highway construction projects is challenging as it requires a high level of human resources. Thus, allowing the public to assess and report any potential misconduct in road and highway construction projects can help monitor EMP performances. This study aims to compare key performance indicators (PIs) for assessing EMP implementation in road and highway construction projects. To achieve the aim, the study objectives are to (1) determine the key PIs for road and highway construction projects, (2) develop underlying components that categorize interrelated PIs, and (3) compare the underlying components between road and highway construction projects. To achieve those objectives, this study first develops a questionnaire survey by conducting a systematic literature review and semistructured interviews with industry professionals. Throughout the process, 39 PIs for assessing EMP performances have been identified. Then, a questionnaire survey was developed using the PIs and distributed to environmental professionals, collecting 111 valid responses. Finally, the data for the study were analyzed using mean score ranking, factor analysis, and agreement analysis among the two project types. This study has identified 18 and 21 key PIs for assessing EMP implementation in road and highway construction projects. The key PIs can be categorized under four underlying components for both types of construction projects: geological, pollution, environmental change, and ecological for roads, and pollution, ecological, public safety, and geological for highways. This study adds to the environmental management literature by comparing potential PIs for road and highway construction projects, potentially helping policymakers and industry practitioners develop public assessments for EMP implementation of road and highway construction projects. [ABSTRACT FROM AUTHOR]

In this study, heavy calcium carbonate was wet modified using a titanate coupling agent, and fabricated titanate-coupled calcium carbonate and styrene–butadiene–styrene (SBS) were used to prepare composite modified asphalt. Microscopic tests such as scanning electron microscopy and x-ray diffraction showed that the surface wrinkle of the modified calcium carbonate was significantly increased, and the enhanced crystallinity and purity were favorable for its compatibility with asphalt (by segregation). Viscosity (135°C) and three major indicator tests showed that the modified asphalt exhibited good high-temperature performance compared to the original asphalt. Dynamic shear rheological and multistress creep recovery tests indicated that the composite modified asphalt exhibited better viscoelastic properties and resistance to permanent deformation than the pure SBS-modified asphalt. This was attributed to the fact that the modifier caused the SBS to swell sufficiently to form a clearly visible three-dimensional spatial network structure in the asphalt (by fluorescence microscope). This allows the matrix asphalt to form an interlocking phase with the polymer modifier, which in turn significantly enhances the relevant properties of the asphalt, as confirmed by fluorescence microscopy. The results of Fourier infrared spectroscopy suggest that the modifier is only physically miscible with SBS or base asphalt. This study can provide a feasible idea for the practical application of bicarbonate composite modified asphalt, which has greater prospects in construction and highway applications. [ABSTRACT FROM AUTHOR]

Civil infrastructure systems have traditionally been designed assuming stationarity in precipitation. However, climate change is making this assumption invalid, affecting both existing infrastructure designed assuming stationarity and the design of new infrastructure. Although many studies have analyzed potential increases in precipitation due to climate change, fewer have attempted to translate these changes into the impact of stream discharge in a way that could be incorporated into infrastructure design. Therefore, this study aimed to assess the potential impact of climate change on both rainfall and peak discharge to aid in bridge and road infrastructure design. Results showed that the median increase in model-derived rainfall intensity across the selected rainfall stations in Virginia was 10%–30% for the midcentury (centered on 2045) and 10%–40% for the end of the century (centered on 2085), with the higher increase for the Representative Concentration Pathway 8.5 (RCP8.5) scenario compared with the RCP4.5 scenario. A regression analysis was performed to relate peak discharge to watershed size for midcentury and end-of-century periods for the study area. In terms of peak discharge, smaller watersheds (<25 km2) had a percent increase for a given return period that was independent of the watershed size. Considering both RCP4.5 and RCP8.5 scenarios, for a 100-year return period, the increase was 39% and 49%, respectively, for the midcentury periods and 36% and 52%, respectively, for the end-of-century periods. For larger watersheds (>25 km2), the increase in peak discharge decreased as the watershed size increased, suggesting a dampening effect for larger watersheds in this coastal plain region of Virginia. For a watershed size of 1,700 km2 , the largest watershed included in the analysis, the percent increase in peak discharge for a 100-year return period was 14% and 39% during the midcentury, and 16% and 40% at the end of the century, for the two emission scenarios. These findings and the general methodology used in the study can aid transportation and water resources engineers in incorporating changing rainfall impacts into assessing current infrastructure and designing future infrastructure. They can also help to prioritize resources for more costly hydraulic analyses of potentially vulnerable infrastructure. The study aims to understand better how climate change will impact future precipitation and how this change in precipitation will impact peak discharge for watersheds of various sizes. Using Virginia as a study region, the median increase in precipitation intensity was found to be between 10% and 30% for the midcentury and 10%–40% for the end of the century across the state. Smaller watersheds (<25 km2) had an increase in peak discharge for a given return period that was independent of the watershed size. In comparison, larger watersheds (>25 km2) had an increase in peak discharge, but the percent increase in peak discharge decreased as the size of the watershed increased, especially for the RCP8.5 emission scenario. Regression equations were developed to provide a first approximation of peak discharge based on the watershed area, the emission scenario, and the return period to aid decision-makers in the region when including climate change impacts when assessing existing or designing new hydraulic structures. [ABSTRACT FROM AUTHOR]

An essential process in earthworks is projecting effective routes for material allocation. In highway construction, haul road planning is a challenge for practitioners once there are few consolidated methodologies to rationally select existing haul routes or construct new ones. Some authors indicated geographic information system (GIS)-based methods for routing through least-cost algorithms. However, most proposed methodologies overlook the logistics related to allocations, not considering supply–demand relations in their criteria. Consequently, through a case study in Brazil, we present an earthwork optimization system that integrated established mathematical programming techniques for allocation and a GIS-based algorithm for haul road construction. In summary, we formulated a model capable of selecting different routes based on their impact on earthworks logistics cost. Thus, we built several paths between source and demand points utilizing two methods. First, based on recent literature, we used a GIS-based least-cost algorithm using the measuring attractiveness by a categorical-based evaluation technique (MACBETH) as a multicriteria support system incorporating multiple economic and environmental parameters. Second, we built routes based on Euclidian distance between the same source and demand points, analyzing if the savings in operational costs would payoff additional expenses of choosing a shorter route. After applying our methodology to the case study, we observed that the proposed procedure presented a lower budget in a reasonable processing time compared with the original project. Therefore, we inferred that the strategy of proposing path alternatives can be significantly efficient when applied to highways. Based on the results, we also found opportunities for improvement of our GIS step once it generated long paths when the distance between source and demand was short. [ABSTRACT FROM AUTHOR]

This paper addresses the confluence of two issues associated with transportation construction: cost overruns, which represent a threat to cost savings, and project bundling, which represents an opportunity for cost savings. The paper hypothesizes that there exists a significant relationship between project bundling practice and the occurrence propensity and severity of cost overrun, and that the nature of this relationship varies across the different project types. Recognizing that current literature lacks adequate evidence regarding the nature of this specific relationship, this paper addresses the question using econometric modeling techniques. The study objective is to quantitatively assess project bundling impacts on the propensity and magnitude of cost overrun and how these impacts vary by project type. The methods used include binary logit and logistic regression specifications. The data were from a highway construction contract database involving 8,782 projects (consisting of 36 project types grouped into six work categories) and 5,180 contracts. The paper finds that, generally, project bundling does affect cost overruns, and that there exists variation of this relationship across the different types of projects. The outcomes of this study can help guide agencies on which project types could be bundled to reduce the occurrence propensity or magnitude of cost overrun as well as the bundling combinations for which cost savings may not be realized. As bundling practices become increasingly prevalent, public agencies interested in adjusting their financial estimates to accommodate possible cost overruns can replicate the study methodology provided in this paper. With the bundling and cost overrun relationship functions that could be developed using their local data, agencies can carry out, in a more reliable manner, the task of contract contingency sum estimation for bundled projects. [ABSTRACT FROM AUTHOR]

Foam lightweight soil (FLS) has been widely used in geotechnical engineering because of their high strength, low density, and thermal insulation. However, few scholars have researched its application to subgrade engineering, especially roadbed widening. In this case, this special artificial soil can significantly reduce the differential settlement of subgrades due to its lightweight and high strength. In the research background, a series of laboratory experiments were conducted to investigate the effects of mixing ratio and fibers on the physical, mechanical, and microporous structural properties of clay-based foamed lightweight soils (CFLS), with clay and cement as the main raw materials. The experimental results indicate that preparing CFLS for road widening using clay soils from around highways as raw materials is an alternative treatment method. During the application process, one should select the optimal mixing ratio and fiber content considering the fluidity, stability, and mechanical strength of CFLS. In addition, the dynamic modulus of elasticity and cumulative plastic strain of CFLS samples also indicate that CFLS has superior dynamic properties compared with cohesive soils and can meet the criteria for road construction. [ABSTRACT FROM AUTHOR]

Competitive bidding is a popular technique State Highway Agencies use for selecting contractors for public construction work. It intends to ensure that construction projects are awarded at the lowest price. However, public owners may award contracts at high prices due to collusive bid arrangements among bidders. The current practices and state-of-the-art methods of bid collusion detection are ineffective because they greatly rely on engineers' estimates, which can be inaccurate, and the similarity in the cost structure of the bids, which experienced collusive bidders can manipulate. This study contributes to the body of knowledge with a novel data-driven collusion red-flag detection framework (CRFD) that utilizes pattern mining techniques and statistical tests for detecting contractors with a red-flag pattern, which refers to a significant difference in the winning rates of a contractor with and without the co-occurrence of other particular contractors. A mechanism is also proposed to incorporate potential, influential factors into the CRFD to increase the detection power or examine possible collusion between different scenarios. The proposed method is expected to assist project owners in detecting early signs of bid collusion and eventually help them significantly enhance their award decision-making. [ABSTRACT FROM AUTHOR]

Competitive bidding in design-bid-build contracts holds the potential to lower bid prices, maximize project outcomes, and promote growth in the construction industry. However, these potential benefits of competitive bidding are contingent upon adequate competition among bidders. State highway agencies (SHAs) traditionally evaluate competition levels predominantly based on the number of bidders, neglecting other key elements such as bidders' competitiveness. Moreover, little research focuses on addressing this limitation. This study proposes a novel data-driven network theory approach to measure competition from the owners' perspective. Specifically, competition is modeled as a bidirected network of connected bidders using their past winning and losing records. We propose different measures of contractors to provide unique insights into the competitiveness of the bidders. These centrality measures are further correlated with the bidding performance using Spearman's rank correlation coefficient. Our findings demonstrate that these proposed centrality measures bear stronger correlations with bidding performance than the number of bidders. By employing this novel approach, SHAs can better understand contractor competitiveness and competition levels during the project-letting phase. [ABSTRACT FROM AUTHOR]

The management and knowledge of landfills are generally inadequate and could lead to significant catastrophes. This is particularly concerning for solid waste landfills due to their large size and potential to threaten nearby structures and residents in the event of landslides. In this paper, we investigated a backfill landslide induced by road construction in a coal mine slag landfill. Our analysis of satellite images and field surveys revealed that the alteration of the mounding morphology at the slope's crest by construction triggered the landslide. We established an engineering geological model of the main sliding plane and utilized the discrete-element program MatDEM to reproduce the landslide's development and predict its final accumulation pattern and impact range. Our study highlights the potential dangers of engineering construction carried out on relatively stable solid landfills. The combined in situ and numerical analysis research methods employed in this study can provide important references for risk assessment and treatment measures. [ABSTRACT FROM AUTHOR]

Roller-integrated compaction monitoring technology has been widely used in highway construction and has played an important role in controlling compaction quality and construction progress. In order to detect and assess the compaction quality of the subgrade accurately in real time based on the analysis of the acceleration signal of the vibrating wheel, a total of four real-time monitoring indexes, namely, peak value of acceleration (Ap), compaction meter value (CMV), root-mean square value of acceleration (Arms), and crest factor value (CF), were selected to characterize the compactness of the soil. To determine which of these indexes is the most appropriate, field compaction experiments under various rolling conditions were carried out on the fifth section of the Hengyong Highway in Hunan Province, China. The data of compaction parameters, compaction quality, and integrated compaction monitoring under various working conditions were collected and subjected to statistical regression analysis. On the basis of the time-frequency analysis of vibration response signals, the CMV could more accurately characterize the compactness of low-liquid-limit silt. In addition, the mapping relations between compaction quality index and roller-integrated compaction monitoring indexes were founded to define the control criterion of roller-integrated compaction monitoring index, namely, CMV, providing scientific guidance for making sure the compaction quality of the subgrade during construction. [ABSTRACT FROM AUTHOR]

Most highway agencies use the default values of the lane distribution factor (LDF) as suggested by their pavement design guidelines. However, the use of the default value of the LDF results in over- or underestimation of the number of standard axle repetitions, especially for multilane roads, which have a larger variation in the movement of vehicles across the entire carriageway compared with one- and two-lane roads. Therefore, this study focused on the accurate measurement of the LDF for multilane roads. Currently, the LDF is estimated as the ratio of the number of heavy vehicles in a design lane to the total number of heavy vehicles moving on the carriageway. However, in the case of multilane roads, the same vehicle can occupy more than one lane, which ultimately results in inaccurate measurement of the LDF. To overcome this issue, a strip-based approach is introduced for a microlevel analysis of the LDF of multilane roads. The vehicle damage factor (VDF) and LDF were obtained by extracting the traffic data collected through the video recording method. The results of the LDF indicate that the channelization of trucks occurred in the intermediate lane instead of the outer lane, which commonly is assumed for the estimation of the number of standard axle repetitions for flexible pavement design. A significant variation was observed in the number of standard axle repetitions estimated using actual LDF and the default LDF values suggested by the Indian Roads Congress. The study finding suggests that the estimation of the actual LDF from field study is essential for the estimation of the number of standard axle repetitions on multilane roads for the design of flexible pavement. [ABSTRACT FROM AUTHOR]

Red beds (RBs) are widely distributed in all continents of the world. With the rapid development of road and railway construction, the construction of roads and railways in RB areas is increasing. However, when RB is the filler, it will expose three aspects of serious deficiencies in compaction, mechanical bearing capacity, and water stability, which will cause fatal harm to the subgrade. Therefore, RB has to be abandoned and cannot be used as a subgrade filler. In this paper, different microwave irradiation temperatures (DMITs) from room temperature of 25°C to 700°C were used to reveal the enhancing mechanism of RB in three aspects based on the analysis results of microscopic composition and structure. The microscopic composition and structure show that RB can be divided into a low-temperature section (25°C–400°C) and a high-temperature section (500°C–700°C) under the microwave condition. The low-temperature section has some improvement in the engineering performance of RB, but the influence is limited. The engineering performance of RB is improved completely in the high-temperature section. Specifically, the coarse size of RB increases with the rise in microwave temperature, which is beneficial for improving fine size. The compaction property of RB is not largely affected by the water content and can still meet the most stringent subgrade filler requirements, even under saturated conditions or 0. The California bearing ratio (CBR) value can maintain more than 20% under the ultimate working condition, far higher than the code requirements. The increase of internal friction angle and cohesion can enhance the stability of the cut slope, which is conducive to construction in remote mountainous areas. The water resistance of RB is positively correlated with the microwave irradiation temperature, especially at 700°C; RB experiences secondary hardening after encountering water, the mechanical strength increases, and the softening coefficient reaches 107.44%. The research shows that after microwave high-temperature stabilization, the engineering characteristics of the RB are thoroughly strengthened, and it becomes a high-quality subgrade filler to eliminate the three diseases of RB subgrade completely. Compared with the traditional method of adding stabilizers, microwave in situ RB stabilization reduces the site construction's complexity, saves a lot of stabilizer use and transportation costs, and can effectively reduce carbon emissions. This study provides a positive perspective on the in situ application of the RB soft rock subgrade. It could be a starting point for understanding the microwave-based stabilization of soft rock soils subgrade filler in situ. [ABSTRACT FROM AUTHOR]

Environmental and financial concerns have motivated road authorities to limit the utilization of natural resources in road construction, particularly the resources that cannot be renewed. To fulfill such requirements, pavement researchers have successfully utilized reclaimed asphalt pavement (RAP) materials as an attractive alternative to their natural counterparts. In practice, rejuvenators are often used to amend the properties of the RAP binder. The addition of the rejuvenator in the mixtures containing RAP materials could completely change the behavior of the mixtures. Such changes in the mechanical responses of the asphalt mixtures are essential aspects of pavements' lifetime performance and should be considered during the asphalt mix design. Although the self-healing performance of asphalt mixtures prepared by virgin materials is well researched, a few research studies have been carried out to investigate the healing properties of asphalt mixtures prepared by RAP materials. This paper examines the influence of the addition of rice bran oil (RBO) capsules on the self-healing performance and mechanical properties of the asphalt mixtures containing various amounts of RAP: 20% and 40% and control mix containing no RAP material. In general, it was found that the addition of the capsules into the mixtures with RAP materials decreased the resilient modulus and flow number (FN) values. As a consequence of the fact that some part of the rejuvenator inside capsules is released into the mixture during mixing and compaction; moreover, the skeleton structure of capsules is weaker than aggregates, which allows the reduction in the maximum density. Further, the addition of capsules into the asphalt mixture without RAP has increased the fracture energy since the inclusion of capsules would increase the bond between asphalt binder and aggregates. In contrast, encapsulated mixtures containing RAP materials had lower fracture energy values compared with their corresponding mixtures without capsule addition. Furthermore, the results revealed that the addition of RBO capsules to the mixtures with RAP materials increased the healing performance of mixtures due to the fact that the reduced viscosity of aged asphalt binder had increased following the gradual release of the rejuvenator; therefore, the microcracks were closed and prevented further damages. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of applying a polyurethane-bonded mixture (PUM) on the pavement overlay for construction or maintenance. Styrene butadiene styrene (SBS) asphalt and epoxy asphalt, the two most common and widely adopted mix designs for highway steel bridge pavement, were selected for a comparative study. First, the performance evaluations and failure analysis of the asphalt mixture and PUM were investigated comprehensively, in terms of low-temperature property, rutting, fatigue, and freeze-thaw resistance. The results showed that the dynamic stability of PUM was over 30,000 cycles/mm and fatigue life was over one million cycles under 800 με. The tensile strength ratio (TSR) value was higher than 90%, which also indicated an excellent freeze-thaw resistance. Then, bond and shear strengths between the steel plate and the mixture were evaluated for the interlayer of the steel bridge pavement structure. X-ray CT scan analysis was adopted to visualize the internal structure of various mixtures, and the average void diameter of PUM was 0.569 mm. Finally, a statistical analysis was conducted for Kendall consistency and Grey correlation. This research established that PUM is a cost-effective and long-lasting solution for pavement overlay on highway steel-bridge. [ABSTRACT FROM AUTHOR]

A case history of surcharge-induced large deformations and noticeable leakages occurring on existing underlying twin tunnels in soft ground is presented in this paper. The field conditions are well-documented in terms of the processes of the surcharge and discharge as well as the structural mechanical responses of the tunnels. The longitudinal distribution curve and evolution of the tunnel vertical displacement are investigated in association with the surcharge and discharge activities. Structural damages and transverse deformations, including water leakages, cracks, unfilled corners, dislocations, and horizontal convergences, are also explicitly examined and analyzed. To derive insight into the relationship between the tunnel deformations and the surcharge, the ground settlements at different elevations due to the surcharge are calculated using a simplified method without considering the effect of the existing tunnel. Further, a modified two-stage method is adopted to estimate the longitudinal tunnel settlements, bending moments, and shear forces, in which the tunnel and underlying ground are modeled as a Timoshenko beam and Winkler foundation, respectively. Finally, for the upcoming preparation for the tunnel operation and planned road construction, practical suggestions for strengthening the tunnel and future construction activities are proposed. [ABSTRACT FROM AUTHOR]

Semiflowable self-consolidating concrete (SF-SCC) is a new type of self-consolidating concrete with flowability, green strength, and shape-holding ability in the fresh state. SF-SCC is cost-effective, energy-efficient, and low-carbon-footprint concrete because vibrators can be eliminated. This paper discusses the fresh, strength (compressive, splitting tensile, and flexure), durability (chloride ion penetration, water absorption, and water penetration), and microstructural properties of SF-SCC mixes with sugarcane bagasse ash (SCBA) as the cement replacing material at 10%–50% by weight of cement. The results show that all the mixes complied with the requirements of fresh properties of SF-SCC. The strength and durability results were used to validate the suitability of such SF-SCC mixes for rigid pavement construction as per the specifications of the Indian Roads Congress (IRC). It can be concluded that the mixes with as much as 40% SCBA can be used in urban roads. All the mixes with as much as 50% SCBA can be used in the construction of road pavements in the interior part of rural areas, i.e., village roads. The study also involved Vise Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR) analysis for ranking of the mixes. [ABSTRACT FROM AUTHOR]

Bridge codes tend to provide general guidance on the thermal gradients acting on bridge decks based on data from historical extreme events that have occurred within a country, without considering the location of the bridge itself. However, the thermal gradient is a function of the climate conditions that occur locally, in the vicinity of the bridge. Thus, a significant number of bridge decks are designed for climate conditions that might not be representative of their locations. The aim of this research is to optimize current guidelines to ensure that thermal gradients are derived based on bridge location. This objective is achieved through the investigation of the relationship that occurs between climate parameters and the resulting thermal extremes. An advanced finite-element platform was used to model the thermal performance of a concrete box girder. Several sets of meteorological data from 18 locations across Canada (representative of different Canadian climate types) were used as input in the thermal models to simulate the temperature distribution within the bridge deck. Upon analysis of the results, it was determined that a correlation exists between the direct normal irradiance (DNI) at a certain location and the resulting thermal differential that occurs between the top and the interior of the cross section. Four categories were defined, with each category representing a range of DNI values and a resulting range of thermal differentials between the top and the interior. To demonstrate the applicability of the established relationship, a case study was performed in which the maximum limit provided by the Canadian Highway Bridge Design Code was investigated across several provinces in Canada. [ABSTRACT FROM AUTHOR]

The commercial use of aggregate is ubiquitous in the construction of buildings and roads because aggregates provide strength, resistance, and support. This paper analyzes the constraints of aggregate rock use in Kurram district, Northwest Pakistan, and to demarcate aggregate resource locations using GIS techniques, weighted overlay analysis, and the analytic hierarchy process (AHP). The undertaken study has considered several appropriate socioeconomic and environmental factors such as land use, distance from highways, rock type, elevation, and slope to diminish conflicts between land users. These variables were mapped using the weighted overlay analysis and the AHP analysis and then ranked in order of importance. The geographical relationships between all thematic data were used to generate the final suitability map of weighted overlay analysis and AHP analysis. The enumerated results have depicted that a number of aggregate prospective areas are prevalent in the study area. The research areas have been classified as low, moderate, or highly suitable based on environmental constraints, transportation network availability, current land use, and mineral-deposit availability. Furthermore, an accuracy comparison between AHP and weighted overlay analysis revealed that AHP analysis has a very high level of precision. As a consequence, the AHP-GIS approach is highly recommended for investigating land resources and resource categorization, which assists policymakers and regional authorities in making decisions and approving quarry authorizations. The purpose of this research is to analyze aggregate resources using GIS techniques. The authors defined the aggregate resources using two different approaches: weighted overlay analysis and the analytic hierarchy process (AHP). The criteria for selecting the quarry site were developed and implemented in a GIS environment. These criteria consider a variety of factors, including the slope, the distance to the road, land use and land cover, accessibility, slope, elevation, and geology. The final suitability maps were generated, and the locations were classified into three parts: low, medium, and high. Operators and decision-makers can use the undertaken analysis as a reference to create an appropriate aggregate plan for spatial development and management. This will make it easier to ensure that aggregate resources are accessible to both present and future generations while balancing extraction activities with an environmentally friendly perspective. [ABSTRACT FROM AUTHOR]

System engineering is used to analyze traffic delay on a test track as a dynamic process using microscale time data. Each driver is required to start from rest and stop at a specific location in the shortest time possible. As such, delay is carefully defined and used as a measure of performance. The focus of the study is to identify triggering delay events and explain their origin. Road network design is treated as an explanatory variable because the test track has two cruising zones with different speed limits. In one direction, the drivers are required to accelerate at the trip midpoint, and in the other direction, decelerate at that point. Stochastic models mimic the behavior of a driver of a leading vehicle and a car follower. Study findings, based on the analysis of 400 test track runs, identify two delay event types that warrant action: (1) eliminate speed drops at a nonbottleneck location, and (2) eliminate extremely long vehicle spacing gaps found on rare occasions in cruise zones. Various tools are used to obtain a firm understanding of the who, what, when, and where of driver decision making. They include acceleration, speed, and position trajectories to clarify driver actions at startup when cruising and stopping; time-series averaging to obtain a global view of operations; and histograms to study individual behavior. Stochastic roadway network model assembly is presented. Discussions on how to improve a behavioral car-following network model (bCFNM) computer simulator, data validity testing, and model parameter calibration are presented. [ABSTRACT FROM AUTHOR]

Quantifying recycled asphalt binder availability in recycled asphalt pavement (RAP) mix design is very essential, as the widely adopted 100% RAP binder availability assumption in RAP mix design never holds correct. Depending on the mix production condition, recycled binder stiffness, and virgin binder properties, the degree of binder availability in the mix is always partial. The present study proposes a simple procedure to estimate the degree of recycled binder availability in RAP mix design. In the proposed methodology, the designer needs to compare optimum binder content of bituminous mixes prepared using white rock aggregate gradation and virgin aggregates, along with mixes designed by blending black rock gradation and virgin aggregates blended in proportion to achieve the target white rock gradation. The binder content in the RAP fraction used in the blending exercise was determined using ignition oven method. RAP mix designs were performed for RAP material collected from two different sources, and design was performed for three mixing durations in a laboratory pug mill—60, 120, and 180s. The mixes were prepared with 50% RAP incorporation level. RAP material was conditioned at 110°C for 2 h, whereas virgin aggregates were superheated to 175°C. Using the methodology proposed, RAP binder availability was found to vary between 92.5% and 96.6% for softer RAP material, 75.9% to 91.5% for mixes incorporating stiffer RAP. With increasing mixing time, even though the total active binder content did not change significantly, a mixture performance test quantified the implication of increased RAP binder availability in mixes. A higher degree of binder activation resulted in mixes being rut resistant, while the same mixes exhibited relatively higher cracking susceptibility. Recycling of bituminous mixes has been considered as one of the sustainable practices in the highway construction industry. In a recycled bituminous mix, the milled material contributes good quality aggregates, and aged bituminous binder. The amount of aged bituminous binder that can be mobilized in the recycling process largely depends on mix production condition, milled, and virgin material property. The paper presents a simple methodology to quantify the degree of bituminous binder which becomes available in recycled mix design. The methodology can be used by mix designers to account for appropriate adjustment in virgin binder grade selection. The knowledge of degree of binder availability would also enable, if one targets to synthesize recycled mixes of a definite binder content. The paper also investigated the implication of different degree of binder availability on mix performance, arising due to different mixing time (production condition) and milled material property. [ABSTRACT FROM AUTHOR]

This summary discusses a paper titled "Study on Instability Process of Slag Landfills: Example of the Subgrade Landslide on Fuxin Nanhuan Road in Liaoning, China." The authors conducted a study on a solid waste landfill that experienced a landslide 50 years after its construction. They analyzed the characteristics of the landfill and used numerical modeling to determine the cause of the landslide. The authors concluded that the construction of the Nanhuan Road disrupted the stability of the landfill, highlighting the dangers of engineering activities near stable inventories. The summary also mentions some comments made by a discusser regarding the paper, including the need for clarification on certain aspects. The discusser also emphasizes the importance of assessing ground conditions before constructing stockpiles and suggests monitoring ground movement and stockpile material. Overall, the paper demonstrates the effectiveness of combining observational and numerical approaches to address instability problems. [Extracted from the article]

This study aims to assess the safety effect of the paved shoulder width of a 175-km six-lane rural highway in India. First, the applicability of the matched case-control (C-C) method in the case of highway segments with multiple crashes was assessed. Second, the safety effectiveness of the paved shoulder and other risk factors were evaluated using the matched C-C method. Three scenarios with different case definitions were developed using the matched C-C method and ordinal logistic regression. The study used 100-m segment-specific speed, volume, geometrics, roadside characteristics, and fatal crash data between 2016 and 2018. Developed scenario results suggested that the matched C-C method can assess crash risks on segments with multiple crashes by defining cases separately or considering the number of crashes as an ordinal variable. Results also suggested that the probability of observing crashes increases as paved shoulder width increases. However, the probability of observing multiple fatal crashes decreases for wide paved shoulder width increases. The safety effectiveness of paved shoulder width assessment showed that a wide paved shoulder had a higher risk of a fatal crash than a paved shoulder width of 1.0 to 1.5 m. The segments with unpaved shoulders were unsafe compared to segments without them. These results can be used to prepare guidelines by road-owning and construction agencies to adopt safe paved shoulder widths for six-lane and multilane highways in India. Results may also support the development of a new highway design policy concerning preferable safe paved shoulder width for multilane greenfield highways in India. [ABSTRACT FROM AUTHOR]

Setting up workable budgets symbolizes the competence of state highway agencies (SHAs) in fulfilling their responsibilities, and unreliable cost estimates can cause economic and political complications. The unclear scope definition and scarcity of project information available at early stages make it hard to generate reliable preliminary estimates. Hence, based on the 1,249 projects retrieved from the Florida Department of Transportation (FDOT) database, this research aimed to develop a cost estimation model using statistical learning methods for SHAs to forecast preliminary costs during the early stages of a transportation project to fulfill different cost control and managerial functions. However, the currently used methods have serious limitations. This study introduced alternative statistical learning approaches to the currently most used methods: least absolute shrinkage and selection operator (LASSO) and general regression neural network (GRNN). LASSO regression, for instance, has proved in other areas of science to be remarkably better in terms of variable selection, interpretability, and numerical stability. In addition, this study also accounted for economic factors in model development because economic conditions are influential on highway construction costs but have received limited attention. Using the same dataset, LASSO and GRNN models were developed, and then their performances were evaluated based on a set of criteria, e.g., the mean absolute error and mean absolute percentage error. In comparison to the current practice with state DOTs, this research contributes to the body of knowledge by introducing a series of objective modeling approaches that can prevent human errors, requiring no substantial experience in preliminary estimating. Besides the introduction of statistical learning methods, this study took economic indicators into account when developing the models because they are important factors but have been ignored in previous studies. In addition, these statistical learning methods can produce reliable estimates in a much faster and more consistent fashion, which is critical, particularly considering the massive workload faced by most SHAs and the allowable time to make a preliminary estimate. The conventionally used cost-based approach, adopted by most departments of transportation (DOTs) in practice, is time consuming and deeply reliant on estimators' experience and sound judgments to make dependable estimates. However, subjective judgments of estimators are often inconsistent and unreliable, leading to erratic and erroneous estimates. The increasingly worsening labor shortage compounds the issue because the accuracy of preliminary cost estimates largely depends on estimators' experience in current practice, requiring a long time to obtain. Therefore, the advantages of this research include the circumvention of human errors because they require no substantial experience in estimating. In addition, these proposed statistical learning methods produce reliable estimates in a much faster and more consistent fashion than the conventional estimating methods, which is critical, particularly considering the massive workload faced by most SHAs and the allowable time to make a preliminary estimate. Based on the 1,249 projects retrieved from the FDOT database, this research aimed to develop a cost estimation model using statistical learning methods for SHAs to forecast preliminary costs during the early stages of a transportation project to fulfill different cost control and managerial functions. [ABSTRACT FROM AUTHOR]

Providing sufficient pavement surface friction (i.e., skid resistance) between vehicle tires and pavement surface throughout the pavement service life is considered to be one of the main objectives of highway design. Moreover, vehicle safety, the amount of consumed fuel, and the wearing rate of vehicle tires generally are influenced by pavement surface friction. In this study, a comprehensive experimental testing program was conducted on different aggregate sources, including calcined bauxite and five alternative local sources, to assess their friction characteristics. The testing program included a British pendulum tester (BPT) and a dynamic friction tester (DFT), which were used to evaluate the friction characteristics of the proposed aggregates, along with basic and durability properties tests. The aggregate imaging measurement system (AIMS) technique was applied to evaluate the aggregate characteristics due to Micro-Deval degradation. This study provides two empirical models for the friction characteristics of high-friction surface treatment (HFST)-application aggregates based on the experimental results. The first model correlates the friction coefficient at 20 km/h (DFC20) with the British pendulum number (BPN). The second model expresses DFC20 as a function of polishing resistance of aggregates, which is represented by the initial and terminal aggregate texture and angularity values measured using the AIMS device with an overall coefficient of determination (R2) of 0.949. The aggregate characteristics (i.e., particle angularity and surface texture) align well with the microtexture characteristics of the investigated sources. [ABSTRACT FROM AUTHOR]

Electronic Construction (e-Construction) is being increasingly used to minimize the amount of paperwork and simplify the daily operations inherent in the construction of highway infrastructures. Electronic ticketing (e-Ticketing) is a part of e-Construction that aids in the transfer of material tickets in a digital manner, accounting for more than half of construction costs; however, the technology has been pilot tested by several states since the beginning of 2013 and has been disbanded for various reasons. The purpose of this research is to pinpoint the challenges in the deployment of an e-Ticketing platform, as well as to determine the adoption rate of state departments of transportations (DOT) and to assess the benefits. The research method includes a combination of literature review and semistructured interviews to achieve the study's objectives. An inductive thematic analysis approach was used to analyze the interview transcripts. The study's findings are related to the reasons for delays and misconceptions about the implementation of the e-Ticketing platform. Internet connectivity at construction sites and high investment costs were found to be the major challenges that have delayed the implementation of the e-Ticketing platform. The study's results will aid decision makers in DOTs and engineers build a standard e-Ticketing platform, implement rules and guidelines, reduce investment costs, execute pilot testing, improve inspector safety, and complete projects in a timely and efficient manner. [ABSTRACT FROM AUTHOR]

In this study, the thermally induced changes in the shear characteristics of unbound granular materials (UGMs) were investigated. A series of drained shear tests were conducted using a large-scale triaxial apparatus under controlled temperatures. The thermal dependence of the peak strength, critical strength, internal friction angle, and dilatancy of UGMs were investigated under different temperatures, initial mean effective stresses, and relative compaction. Dense UGMs tended to expand during heating and slightly contract during cooling. In the heating and cooling process, a nonlinear relationship was observed between thermal deformation and temperature. Thermal deformation was attributed to the deformation, movement, and rotation of soil particles and closely related to the initial mean effective stress and relative compaction. A thermal softening effect was observed during the shear test, and the peak strength decreased with increasing temperature. However, negligible thermal effects were observed relative to residual strength. The effect of temperature on the shear characteristics of UGMs was primarily related to the thermal expansion of pores in the soil skeleton. The relationship between peak strength and initial thermal volumetric strain was found to be exponential. Considering the thermal effect, a normalized semi-empirical model of the parabolic Hvorslev envelope for dense UGMs was proposed to supply guidelines for road base design. [ABSTRACT FROM AUTHOR]

Highway agencies strive to carry out maintenance of traffic during road project implementation in a bid to reduce the safety and mobility adversities that typically accompany work zones. In certain cases, the agency resorts to a full road closure strategy, where the project location is blocked from traffic use and traffic is detoured to an alternate route, thus bypassing the project location. Often, there exist a number of alternative paths that could be used for the detour. Few specific guidelines exist for defining a detour path, resulting in technical, financial, and operational constraints dominating the detour planning process. The challenge, therefore, is how to identify the best candidate detour path based on several factors including, but not limited to technical, financial, and operational considerations. This paper proposes a methodology to address this question. The methodology is based on a multicriteria decision-making technique and is demonstrated using two case studies. The case study results are discussed in the context of the relative weight specifications of the key performance indicators (KPIs). The results highlight the impact of the KPIs and their weights on detour route choices. The methodology can be used as a basis for developing a decision-support tool to assist practitioners in selecting the best detours based on a comprehensive range of KPIs. This research contributes managerial aspects that can reduce the subjectivity in maintenance of traffic (MOT) strategy selection and lower the inconsistencies of prescribed detours for similar project conditions. [ABSTRACT FROM AUTHOR]

Every year more than 100 fatal accidents occur in road work zones. One of the major causes of pedestrian workers being struck by construction vehicles is that workers become habituated to the warning alarms of these vehicles. Researchers suggest that workers with certain personality traits (e.g., boredom proneness and extraversion) are more likely to become habituated to workplace hazards and therefore have a higher likelihood than other workers of being involved in an accident. This study investigated which aspects of personality correlate with workers' accident proneness and their vulnerability to habituation to warning alarms in road work zones. An experiment with actual road construction workers was performed using a virtual reality (VR) environment. The results reveal that boredom susceptibility (one of the subdimensions of the personality trait of sensation seeking) is negatively correlated with workers' attention to warning alarms, and that boredom-prone workers were more likely to be involved in a virtual struck-by accident. The findings of this study provide conceptual motivation for tailoring safety training to individual workers' personality traits. [ABSTRACT FROM AUTHOR]

Crushed waste rocks, generated from mining operations, have been widely used for mining infrastructure constructions such as haul roads because of their low cost, high strength, and availability. Crushed waste rock gradation can, however, vary greatly, depending on blasting, mineralogy, and crushing process, but it is a key factor influencing the mechanical properties of crushed waste rocks (including resilient modulus, permanent deformation, and shear strength). Gradation should therefore be optimized to enhance their performance in the field. A series of repeated load and monotonic triaxial tests were carried out on crushed waste rocks with different gravel-to-sand (GS) ratios and fines contents (FC). Results showed that the optimum GS ratio was between 1 and 1.5 and contributed to provide higher resilient modulus and shear strength, and lower permanent strain. An increase in FC could, to the contrary, result in the decrease of resilient modulus and permanent strain and also a significant increase in shear strength. The structure state of crushed waste rocks was quantified using the cm model, and the mechanical properties of crushed waste rocks were dominated by sand and fines when the content of sand and fines was higher than 80%, while it was dominated by gravel particles as the content of sand and fines was lower than 60%. Here, the MR − θ model and the Rahman and Erlingsson model (extended using time-hardening approach) were well adapted to describe resilient modulus and accumulated permanent strain, respectively. Prediction models were also developed based on correlation analyses to predict the resilient modulus and permanent strain of crushed waste rocks based on gradation parameters. [ABSTRACT FROM AUTHOR]

In the US, hundreds of people lose their lives each year, and many more are injured, in street and highway maintenance and construction work zones. The Occupational Safety and Health Administration (OSHA) mandates the use of temporary traffic control to address overall safety performance in roadway construction and maintenance projects. However, statistics reveal the need to further identify and investigate the main contributing factors to occupational incidents within work zones. This study reviewed work zone fatal incident investigation reports carried out by the Fatality Assessment and Control Evaluation (FACE) Program. The review categorized the reports based on incident nature into internal-source incidents and vehicle intrusion incidents. Accordingly, this study sheds light on the safety of construction workers within road work zones. Specifically, the study focused on temporary traffic control plans and internal traffic control plans (ITCPs). This study highlights the critical contribution of ITCPs to internal-source incidents. Currently, there is no requirement to create and implement an ITCP. As a result, a justification for OSHA's use of the general-duty clause is suggested to enforce the utilization of ITCPs in roadway work zones. In addition, recommendations to improve overall FACE investigation efficiency and temporary traffic control layout are suggested. This study will aid construction firms and public agencies in improving the overall safety of roadway work zones to reduce occupational fatal and nonfatal injuries. [ABSTRACT FROM AUTHOR]

This study aimed to identify the segment-specific risk factors for rear-end crashes on an expressway in India. The fatal crash data were analyzed from August 2012 to October 2018 with road geometry details, speed, volume, and roadside data. Negative binomial (NB) models with a random parameter framework accounted for the unobserved heterogeneity across the segments. A NB model with fixed parameters (FPNB) was used as a base model against basic random parameter NB (RPNB) and correlated random parameter NB (CRPNB) models. The results indicated that rear-end crashes comprised 49% of the total fatal crashes. Truck and car occupants constituted the highest share of victims in rear-end crashes. As per the estimate of log-likelihood for the developed models, CRPNB was best. The results of the RPNB model suggested that speed, Annual Average Daily Traffic (AADT), horizontal alignment radius, and vertical curve length were the significant variables. In the case of the CRPNB model, speed, AADT, and vertical curve length were the significant variables. Segments where a village was present along the expressway were comparatively safer. Segments where entry and exit ramps and underpasses were present and segments with hazards had higher chances of being associated with rear-end crashes. The study's findings provide valuable insights into proposing interventions for reducing rear-end crashes on expressways in heterogeneous traffic conditions. Detailed investigations with additional data are required at segments with entry-exit ramps and horizontal and vertical curves. To sum up, the findings of this study may assist highway agencies and design engineers in designing new or evaluating existing expressways from a safety viewpoint. [ABSTRACT FROM AUTHOR]

The increasing awareness of sustainability has resulted in the progressive regulation of contractors for public projects to lower the pollution associated with their equipment fleet. Nevertheless, such implementation has not been fully developed yet due to the challenges this presents to contractor profitability and the practical usefulness of decision-support tools. This paper developed a sustainable equipment fleet (SEF) decision-support optimization model with the capability to reduce the CO2 emissions of construction equipment and to minimize the equipment fleet modification cost, subject to the contractor's budget and time constraints. The model utilizes a multiobjective genetic algorithm (GA) to search for the combination of equipment utilization, equipment model, and sustainable options that provide the optimal equipment fleet options to contractors. The results from the case study of a road construction project demonstrated the tradeoff between emissions and costs, with a wide range of optimal sustainable equipment fleet options. In addition, the fuel equivalent ratio (FER) and the equipment cost-effective ratio (CER) were newly established to normalize pollutant generation and equipment investment and to enable equipment comparisons for facilitating equipment selection by the contractor. The findings suggested that equipment selection involving a lower FER is preferable for sustainability and likewise, a lower CER for the cost aspect. However, effectiveness was measured as the proportion of FER to CER, with higher effectiveness when the proportion was lower. This paper facilitates the assessment and prioritization by construction companies of their equipment investment options to satisfy sustainability requirements. [ABSTRACT FROM AUTHOR]

Pay for Performance (PFP) is a statistical-based quality assurance specification used to evaluate asphalt concrete construction for projects having mix quantities greater than 7,260 t (8,000 US tons). The contractor pay is adjusted based on mix field density, air voids, and voids in mineral aggregate. In this study, data were analyzed from the 2015 to 2017 highway construction seasons in Illinois to determine variability trends. Density was the major factor driving contractor pay disincentives in PFP, followed by air voids. To identify the impact of construction field density consistency on the final pay factor, a sensitivity analysis was performed to determine the changes in the contractor pay with respect to variability, which is measured by standard deviation. In addition, an econometric analysis based on sensitivity analysis using linear regression was conducted. The results showed that a 1% reduction in density standard deviation led to a 0.066 increase in density pay factor. Based on the 79 projects analyzed, if the density standard deviation had been reduced from 1.67 to 1.0, the average increase in pay per project would be $38,000. [ABSTRACT FROM AUTHOR]

A passenger vehicle's fuel-powered engine compensates for its dissipated energy, which is caused by road roughness. This paper presents an integrated vehicle–pavement approach and investigates the excess fuel consumption of a seven-degree-of-freedom (DOF) full-car model on rough pavements. In the approach, a nonstationary Laplace process is used to artificially generate road roughness profiles with consideration of local roughness variance and parallel roughness correlation. The proposed mechanistic approach quantifies the impact of road roughness and vehicle dynamic characteristics on excess fuel consumption. The study concluded that overlooking local roughness variance, an indicator of road roughness nonstationarity, may underestimate excess fuel consumption by 30%. Compared with a two-dimensional (2D) half-car model, a three-dimensional (3D) full-car model reduces computation error of excess fuel consumption by approximately 11%. For practical implementation, the extended roughness-speed-impact (ERSI) model (R2=98%) is developed to estimate roughness-induced energy dissipation of five two-axle vehicles. [ABSTRACT FROM AUTHOR]

Construction materials and related management, handling, and storage provisions account for a large portion of road construction expenses. For that reason, improved material flow monitoring techniques can achieve significant cost and time savings, as well as better quality control. This study assessed the performance of a solid-state pulsed time-of-flight laser lidar profilometer in measuring the volume of soil stockpiles and road layer thicknesses. The 3D (X, Y, Z, and intensity) image calculation was based on the analysis of multiple combined point clouds measured with an excavator-integrated profilometer. Error analysis confirmed the accuracy of road layer thickness estimation within one centimeter and an error level of approximately 3% when measuring soil stockpile volumes. In conjunction with a theoretical model of the superstructure, this 3D measurement technique can help contractors and supervisors ensure road quality. [ABSTRACT FROM AUTHOR]

In winter, the ice and snow on the asphalt pavement reduce the friction coefficient of the pavement, which may lead to serious traffic accidents and large-scale congestion. Taking preventive measures to ensure traffic safety by accurately predicting road surface temperature is an economical and environmentally friendly solution. However, road surface temperature (RST) prediction is a challenging task due to the complicated uncertainty and periodicity. To improve the accuracy of RST prediction, this paper aims to propose an advanced ensemble deep learning model using a gated recurrent unit (GRU) network and long short-term memory (LSTM) network. The ensemble model predicts RST by extracting the periodicity of RST and incorporating the lag and accumulation effects of meteorological factors. To verify the applicability of the ensemble model, RST data and climatic data were collected from a road weather station in Jiangsu, China. Extensive experiments are conducted including predictions for 1, 3, and 6 h ahead. The results demonstrated that the performance of the proposed ensemble deep learning model is validated for 1-, 3-, and 6-h nowcasts of RST, with mean absolute error (MAE) of 0.345, 0.833, and 1.743, respectively, and the prediction accuracy was higher than that of the baseline models [convolutional neural networks (CNN)-LSTM networks, support vector regression (SVR), and backpropagation neural network (BP) networks]. [ABSTRACT FROM AUTHOR]

This paper examined the applicability of the pruned exact linear time (PELT) algorithm for optimal change-point analysis to delineate pavement into homogeneous sections based on road condition. The primary objective of the study was to address some of the limitations associated with existing delineation approaches, such as the AASHTO cumulative difference approach (CDA) and the Bayesian binary segmentation method. The paper presents a mathematical framework for the optimal change-point analysis of pavement deflection data collected on a runway of an international airport. Through an analytical comparative study, the paper demonstrated how the proposed approach is better than existing delineation methods in terms of accuracy in identifying the change points, flexibility in the choice of the number of homogeneous sections, and computational time. The approach provides an opportunity for practitioners and road agencies to integrate their experience and knowledge of the road network into decision-making about the location of change points and their count without compromising computational accuracy. The proposed method was found to be robust because the solutions are independent of the parameters chosen for the analysis. [ABSTRACT FROM AUTHOR]

Unpaved roads are an important part of the road transportation system of many countries and they contribute to the accessibility of remote communities and businesses. Despite the importance of unpaved road networks on social and economic development of remote regions, research on semiautomated and automated assessment of these roads is limited. This paper proposes low-cost computer vision–based solutions for assessment of unpaved roads using two approaches: unmanned aerial vehicle (UAV) and participatory-based imaging methods. Both methods use deep neural network to process captured images and locate major road distresses, including potholes, rutting, and corrugations. In addition, a method is proposed to estimate the size of detected potholes in the UAV-captured video frames. Each of the proposed methods was evaluated using a set of experiments, which demonstrated promising performance in assessment of these infrastructure assets that are vital for reliable access of rural and remote communities. [ABSTRACT FROM AUTHOR]

Cracking risk of cementitious materials remains one of the serious problems in the construction and highway field. Here, a series of pH-sensitive microgels with different anionic content and crosslinking density have been successfully synthesized and applied in cement mortar. The absorption behavior and pH sensitivity of microgel in aqueous solutions were determined. The effects of microgel on hydration degree, autogenous shrinkage, and compressive strength of cement mortar were studied. Experimental results indicate that the microgel exhibits less desorption in the pore solution and releases water timely in pH from 12–13. Despite the different anionic content of microgels, the addition of microgel with moderate crosslinking density is 0.19%∼0.31% , which can alleviate the autogenous shrinkage of cement mortar. The compressive strength of mortar can be increased by about 5.7 MPa by the microgels with low anionic content and moderate crosslinking density, thereby showing excellent internal curing effect. [ABSTRACT FROM AUTHOR]

Intelligent compaction (IC) has been successfully used for soil and base compaction of highways. However, the application of IC technology to monitor the construction quality of asphalt pavement faces complications with compaction processing. This study monitored the compaction process of asphalt layers using an IC-based method. The compaction data were first collected during the construction of a local road in Mardan, Pakistan, including IC data, in-place density, and temperature at the asphalt layer surface. The collected IC data were then used to compute the intelligent compaction measurement values (ICMVs). The support vector regression analysis was performed to predict the roller amplitude and in-place density using the ICMVs. To explore the correlations in compaction measuring/monitoring indicators, this study also explored the correlations between the ICMVs with core density, temperature, and amplitude. Experiment results indicated that the predicted roller amplitude values from the support vector regression model were close to the measured ones. There were high correlations between the roller amplitudes and temperatures with the compaction measurement values (CMVs). In contrast, the correlation between the in-place core densities and CMV values was low. Additionally, the CMVs of the backward pass were higher than the forward one in each compaction cycle because the pavement density increased and the air void decreased after each forward pass. [ABSTRACT FROM AUTHOR]

Previous studies on connected autonomous vehicles (CAVs) examined pavement performance and lane widths separately and in isolation, and without consideration for roadworks conditions. Hence, this study presents a holistic, optimal highway design solution for connected autonomous trucks (CATs) by testing pavement failure and traffic performance under different cross-sectional configurations incorporating a dedicated CAT lane for both normal and temporary traffic management (TTM) arrangements. Firstly, a dual three-lane motorway (D3M) was selected as a base case site. Next, previous research on substandard lanes was used to produce five nonstandard cross-section alternatives, which were then modeled using commercially available software. Capital investments to implement the alternatives were calculated by applying established industry construction cost models. Each cross-section was then subjected to different CATs penetration rates (PRs) and wheel wander regimes, and their pavement structural deterioration analyzed using the Texas Mechanistic-Empirical Asphalt Concrete Pavement Design and Analysis System (TxME) software. From this, maintenance frequencies and costs were determined. The study estimated delays and delay costs during TTM over a 20-year design period. Finally, initial investment, rehabilitation and delay costs were combined. It was found that the lowest life-cycle cost (LCC) of £19,091,470 occurred for high (80%) CAT PR operating under Standard D3M, whereas the highest LCC of £152,728,100 was also for high PR, but under Substandard D4M. Optimal LCC was found to change with different PRs. Hence cross-sections should be dynamically modifiable, given the anticipated gradual increase in PRs over time. [ABSTRACT FROM AUTHOR]

Presently, the application of cold-mix asphalt (CMA) in structural layers of pavement is limited due to the slow curing rate and low early-life strength. This study attempts to achieve the reduction in curing period and improvement in strength development of CMA by using nonconventional fillers (NCFs) such as fly ash, ground granulated blast-furnace slag (GGBS), rice husk ash (RHA), and fly ash and GGBS activated with RHA. Curing rate was evaluated using moisture loss monitoring of mixture and compacted specimens of CMA. Strength development was evaluated using indirect tensile strength testing and wheel tracking testing. Laboratory investigations revealed that curing period and temperature have a significant impact on the rate of moisture loss and strength gain. Mechanical strength increased with the increase in curing period and temperature for cold mixes with NCFs. CMA with GGBS activated using RHA exhibited higher curing rates than conventional CMA and substantially higher early-strength development among all the mixes considered. This is due to the combined effect of moisture loss and accelerated hydration process. Statistical analysis also indicated that the improvement was significant. Thus, the use of GGBS with RHA as activator by partial replacement of mineral filler is a potential solution to prolonged curing period and weak early-life strength of CMA. Cold-mix asphalt is a sustainable paving mix with economic and environmental advantages. All the steps involved in the construction of the road using a cold mix are done at ambient temperature. Increasing the application of cold-mix asphalt is highly essential. The long time required for curing and the low early strength deter the extensive use of cold mixing in the field. This study suggests that the use of cold mixes in which ground granulated blast-furnace slag with rice husk ash are incorporated as filler helps in resolving these issues by increasing the curing rate and early strength of cold mixes. The study recommends using 25% stone dust, 50% ground granulated blast-furnace slag, and 25% rice husk ash as filler. Because ground granulated blast-furnace slag and rice husk ash are industrial and agricultural waste materials, respectively, using these materials is a sustainable way of resolving the problems of cold mixing. Also, as these materials are easily available, and the modified mix can be easily produced; this can be conveniently implemented in the field. This can pave the way to the use of cold mixing in the top layer of heavily trafficked roads as well. [ABSTRACT FROM AUTHOR]

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal. [ABSTRACT FROM AUTHOR]