Truck Configuration Research Articles

Advancing infrastructure resilience: machine learning-based prediction of bridges’ rating factors under autonomous truck platoons

AbstractThe operational characteristics of freight shipment will significantly change after the implementation of Autonomous and Connected Trucks (ACT). This change will have a significant impact on freight mobility, transportation safety, and the sustainability of infrastructure. Truck platooning is an emerging truck configuration that is expected to become operational in the future due to the rapid advancements in connected vehicle technology and autonomous driving assistance. The platooning configuration enables trucks to be connected with themselves and the surrounding infrastructure. This arrangement has shown to be a promising solution to improve the vehicles’ fuel efficiency, reduce carbon dioxide emission, reduce traffic congestion, and improve transportation service. However, platooning may accelerate the damage accumulation of pavement and bridge structures due to the formation of multiple load axles within each platoon since those structures were not designed for such loads. According to AASHTO, bridges are designed based on a notional live load model comprised of one or two trucks per lane in conjunction with or separate from an applied uniform load (AASHTO, LRFD 2022). This damage, if accumulated, its repair would require billions of dollars from the government and would impede the movement of both people and goods. The potential damage to infrastructure may arise due to various factors such as the number of trucks in a platoon, gap spacing between trucks, and the type of trucks. This research work includes a thorough parametric study with 295,200 computer simulations using SAP 2000. The goal was to evaluate the effect of different truck platooning configurations on the load rating of existing bridges. The obtained results served as the dataset for training various machine learning models, including Random Tree, Random Forest, Multi-Layer Perceptron (MLP), Support Vector Regression (SVR), K-Nearest Neighbor (KNN), and Extreme Gradient Boosting (XGBoost). Results showed that Random Forest model performed the best, with the lowest prediction errors. The proposed machine learning model has shown its effectiveness in identifying optimal platooning configurations for bridge structures within the scope of the study. Graphical Abstract

Impact of rest period on asphalt concrete permanent deformation

Truck platooning has several advantages including congestion reduction, safety, and fuel efficiency. However, there are concerns regarding its impact on pavement performance due to channelized traffic and reduced spacing. A rest period governed by the distance between each truck can have a significant impact on asphalt pavement performance due to time dependent deformation characteristics of asphalt materials. Despite numerous studies available in the literature explaining the rest period effect on fatigue cracking, the impact on permanent deformations is relatively less studied. In this paper, we present the results to characterize the impact of rest period on the permanent deformation characteristics of two asphalt concrete (AC) mixes using four different types of binders. The experimental program included repeated load permanent deformation experiments coupling rest period with various stress and temperature configurations. Increasing rest periods from 0.18 s to 2.5 s increased permanent deformations consistently for the two mixes. The results are consistent with the hardening-relaxation or hardening–softening mechanisms describing the reorientation of the aggregate structure from a more resistant to less resistant state to deformations as rest duration increases. It was also shown with the customized multiple stress creep recovery experiments that the effect of rest period on mixture level permanent deformations could not be attributed to the binders’ deformation characteristics. Rest period impact was found to be as important as temperature and stress magnitude for asphalt mixture’s permanent deformation resistance. Various truck platoon scenarios can be compared to conventional truck configuration and loading assumptions using the results presented in this paper.

Probability-based static truck loading model for rural bridges in Saskatchewan

A study was conducted to establish a new truck load model intended for the evaluation and design of bridges with simple spans of 20 m or less located on rural roads in Saskatchewan. Monte Carlo simulation was used to generate truck data sets based on site-specific traffic conditions determined from a traffic count program conducted between 2008 and 2012 across all 296 rural municipalities, and data collected from six weigh-in-motion stations in the province from January to December 2013. All axle weights and spacings were modelled as probabilistic parameters. The critical truck configuration featured a truck tractor with a steering axle and tandem axle group, and a truck trailer with a tridem axle group. Truck models with a common axle configuration but varying weights were developed for various reference periods that reliably reproduced extreme nominal load effects over those periods. The use of other data sets may lead to different results.

Assessment of commercial truck driver injury severity based on truck configuration along a mountainous roadway using hierarchical Bayesian random intercept approach

For the last decade, disaggregate modeling approach has been frequently practiced to analyze truck-involved crash injury severity. This included truck-involved crashes based on single and multi-vehicles, rural and urban locations, time of day variations, roadway classification, lighting, and weather conditions. However, analyzing commercial truck driver injury severity based on truck configuration is still missing. This paper aims to fill this knowledge gap by undertaking an extensive assessment of truck driver injury severity in truck-involved crashes based on various truck configurations (i.e. single-unit truck with two or more axles, single-unit truck pulling a trailer, semi-trailer/tractor, and double trailer/tractor) using ten years (2007–2016) of Wyoming crash data through hierarchical Bayesian random intercept approach. The log-likelihood ratio tests were conducted to justify that separate models by various truck configurations are warranted. The results obtained from the individual models demonstrate considerable differences among the four truck configuration models. The age, gender, and residency of the truck driver, multi-vehicles involvement, license restriction, runoff road, work zones, presence of junctions, and median type were found to have significantly different impacts on the driver injury severity. These differences in both the combination and the magnitude of the impact of variables justified the importance of examining truck driver injury severity for different truck configuration types. With the incorporation of the random intercept in the modeling procedure, the analysis found a strong presence (24%–42%) of intra-crash correlation (effects of the common crash-specific unobserved factors) in driver injury severity within the same crash. Finally, based on the findings of this study, several potential countermeasures are suggested.

Analysis of an automotive thermoelectric generator coupled to an electric exhaust heater to reduce NOx emissions in a Diesel-powered Euro VI Heavy Duty vehicle

This study presents a new approach to minimize the amount of NOx emitted by diesel engines of Heavy-Duty Vehicles during low engine regimes and low gases temperature conditions. We propose the addition of an electric Exhaust Gas Heater (EGH) to make the SCR system inject the urea solution at low engine regimes. The second part of this study focuses on the viability to use an Automotive Thermoelectric Generator (ATEG) to generate the energy required by the EGH and thus avoiding the need to consume electrical energy from the vehicle’s system. This EGHATEG system is designed to be energetically closed, so there is no extra consumption of fuel. Experimental results show that NOx emissions reduce up to 80% when an EGH is added to a standard diesel-powered Euro VI Heavy Duty truck configuration. Simulations show that an ATEG installed downstream of the aftertreatment system can produce the energy required by the EGH. This system can improve SCR efficiency up to 55% during low engine regimes.

Evaluation of the Impact of Timber Truck Configuration and Tare Weight on Payload Efficiency: An Australian Case Study

The forest industry tends to plan, and model transportation costs based on the potential payload benefits of increased legal gross vehicle weight (GVW) by deploying different configurations, while payload benefits of a configuration can be significantly influenced by the vehicle design tare weight. Through this research the relative benefit of increased legal GVW of different configurations is compared across Australia over a 13-year period from 2006 to 2019, by examining data collected post operation across multiple operations. This approach is intended to offer realistic insight to real operations not influenced by observation and thus reflect long-term operating behaviour. The inclusion of the three most common configuration classes in Australian forestry over a 13-year period has also allowed the exploration of load management between configurations and potential trends over time. When considering the legal GVW and the tare weight impacts across the fleets, the semi-trailer has an 8 t payload disadvantage compared to B-Doubles and 19.6 t disadvantage compared to road trains.

Nox emissions reduction analysis in a diesel Euro VI Heavy Duty vehicle using a thermoelectric generator and an exhaust heater

Selective Catalytic Reduction systems (SCR) are very efficient on reducing NOx. However, they only perform properly when exhaust gas temperature is higher than 180 °C. This means that for low engine regimes combined with cold engine temperatures, SCR systems remains inactive.This study presents a new approach to minimize the amount of NOx emitted by diesel engines of Heavy-Duty Vehicles during low engine regimes and low exhaust gases temperature conditions. We propose the addition of an Automotive Thermoelectric Generator (ATEG) coupled to an electric Exhaust Gas Heater (EGH) to make the SCR system inject the urea solution at low engine regimes. This EGH-ATEG system, which can be retrofitted in any existing vehicle, is designed to be energetically closed, so there is no extra consumption of fuel. Experimental results show that NOx emissions can be reduced up to 80% when an EGH is added to a standard diesel-powered Euro VI Heavy Duty truck configuration. Apart from that, the use of an ATEG installed downstream of the aftertreatment system can produce the energy required by the EGH, which means that the EGH-ATEG system can work energetically autonomous and independent from the vehicle’s electrical system. This system can improve SCR efficiency up to 55% during low engine regimes.

Simulation study on fatigue behavior of wrap-around weld at rib-to-floorbeam joint in a steel-UHPC composite orthotropic bridge deck

As an innovative cement-based material, the ultra-high performance concrete (UHPC) has been recently utilized to reinforce the orthotropic steel bridges. Based on an in-situ steel-UHPC composite orthotropic deck bridge, both the field testing and multi-scale finite element analysis modelling were conducted to investigate the fatigue behavior of wrap-around weld at rib-to-floorbeam (RF) joint, and factors influencing stress were further studied to achieve an infinite fatigue life. It is found that a primary tensile stress cycle is jointly produced by the axle group of truck, while a small reversal compressive cycle will be generated when the axle is directly located on the floorbeam. The stress behavior of fatigue detail is extremely sensitive to the localized effect of axle loading instead of entire truck configuration. Since significant stress concentration and high stress gradient exist in the wrap-around weld, it is essential to utilize the hot-spot stress approach rather than nominal stress approach. The wrap-around weld presents an obvious out-of-plane bending deformation, which results from the torsion effect and Poisson’s effect. The Dong’s structural stress reveals that the surface stress is dominated by bending stress. The application of bulkhead can greatly improve the fatigue performance of wrap-around weld. Both the large-scale rib and U-shaped rib are preferable, which are available to achieve an infinite fatigue life without extra fabrication procedure.

Driving Mode Optimization for Hybrid Trucks Using Road and Traffic Preview Data

This paper proposes a predictive driver coaching (PDC) system for fuel economy driving for hybrid electric trucks using upcoming static map and dynamic traffic data. Unlike traditional methods that optimize over engine torque and brake to obtain a speed profile, we propose to optimize over driving modes of trucks to achieve a trade-off between fuel consumption and trip time. The optimal driving mode is provided to the driver as a coaching recommendation. To obtain the optimal solution, the truck dynamics are firstly modeled as a hybrid controlled switching dynamical system with autonomous subsystems and then a hybrid optimal control problem (HOCP) is formulated. The problem is solved using an algorithm based on discrete hybrid minimum principle. A warm-start strategy to reduce algorithmic iterations is used by employing a shrinking horizon strategy. In addition, an extensive analysis of the proposed algorithm is provided. We prove that the the coasting mode is never optimal given the truck configuration and and we provide a guideline for tuning parameters to maintain the optimal mode sequence. Finally, the algorithm is validated using real-world data from baseline driving tests using a DAF hybrid truck. Significant reduction in fuel consumption is achieved when the data is perfectly available.

Analysis of the truck transportation of eucalyptus logging residues to Portuguese power plants

ABSTRACTTransportation of logging residues (LR) from eucalyptus plantations to regional bioenergy plants may incur high unit costs that restrict their removal from the forest, aggravating fire risk. This paper compares the cost of truck transportation of eucalyptus LR in Portugal, for alternative operational plans, aiming to improve biomass supply efficiency and to promote cost reduction. The following factors were analyzed: (1) the relation between truck configuration, biomass physical characteristics and payload, and (2) the relation between the transportation cost of a unit of mass and of a unit of heat and the biomass moisture content (MC). Direct transport of LR before comminution, with a 70 m3 semi-trailer, achieves 65% of the maximum payload, for the mean MC of 42%, and the cost represents46% of the payload value. Direct transport of shredded biomass with a 77 m3 semi-trailer achieves 76% of the maximum payload (mean MC of 43%) and the cost represents a fraction up to 62% of the payload value. Using a 90 m3 semi-trailer the payload increases to 80% of the maximum and the transportation cost decreases to less than 42% of the biomass value. For small scale logging operations a two echelon supply system promotes efficiency, allowing centralized shredding after additional natural drying that improves the quality of fuel, and involves a transportation cost of 10€ Mg−1 (MC of 43%) for a total distance of 33 km.

THE EVOLUTION OF HIGH PRODUCTIVITY VEHICLES IN AUSTRALIA AND THEIR BENEFITS

Although the Australian road freight transport industry has seen three mass limits reviews in the mid 1970s, the mid 1980s and in the late 1990s, (Hassall, 2005), there were two very significant truck configuration changes that happened in the mid 1980s and then again in the early 2000s. The first was the trials of a variant of the Canadian B-train (the B-Double) which was introduced into Australia in the mid 1980s. This ‘Australian’ B-Double could achieve payloads some 30% to 40% higher than the conventional ‘semi trailer’ articulated combination. By 2016 some 18,900 of these vehicles were operational in Australia. The second adoption of new vehicle configurations started in 1999 through the National Road Transport Commission (NRTC), who adopted, and further developed, another Canadian concept, that of “Performance Based Standards” (PBS). This effectively allowed for new, flexible truck designs, as long as the vehicles performed against a set of 17 specific technical engineering performance criteria. This Performance Based Standards approach, since 1998, also allowed even larger configurations to B-Doubles to be used by operators. The benefits already of these new configurations has delivered billions of dollars in kilometre savings to the road freight industry and to its customers, as well as very significant safety benefits to the community.

Trucks at Roundabouts: A Synthesis Study

Roundabouts in United States and other countries have been proved to be very successful, effective, and a safe traffic control treatment. Roundabouts in the context of regularly expected truck configuration have also been successful for effective roundabout designs; however, there are always some site specific issues for trucks accommodation at roundabouts. Therefore, there is a great need for an informational guide in the form of synthesis report for roundabout designs specific to unique trucking traffic activity. While there are not significant literatures and studies in this subject, there are few studies/reports spread out which address various issues in this subject area. This study attempts to synthesize the research and knowledge of truck accommodation at roundabouts by synthesizing various research studies, reports, and articles; various subject areas such as roundabout designs for trucking activity, roundabout designs and accommodation strategies for specialized trucking activity such as oversized trucks, truck safety at roundabouts, and motor carrier perspective of trucking at roundabouts have been analyzed and relevant knowledge has been synthesized. This synthesis can be useful o researchers, designers, planners, and decision makers to determine effective ways to address specific trucking related issues at a roundabout.

Hardware-in-the-Loop Pneumatic Braking System for Heavy Truck Testing of Advanced Electronic Safety Interventions

The rapid innovation underway with vehicle brake safety systems leads to extensive evaluation and testing by system developers and regulatory agencies. The ability to evaluate complex heavy truck braking systems is potentially more rapid and economical through hardware-in-the-loop (HiL) simulation which employs the actual electronics and vehicle hardware. Though the initial HiL system development is time consuming and expensive, tests conducted on the completed system do not require track time, fuel, vehicle maintenance, or technician labor for driving or truck configuration changes. Truck and trailer configuration and loading as well as test scenarios can be rapidly adjusted within the vehicle dynamics simulation software to evaluate the performance of automated safety interventions (such as ESC) over a wide range of conditions. Hardware-in-the-loop simulation does not obviate the need for all track testing; vehicle models for simulation must be validated against track data for each truck platform. But HiL simulation can supplement and extend track data for tests at higher speeds, low friction surfaces, and alternate vehicle configurations. A HiL pneumatic braking system was developed for this purpose by the National Highway Traffic Safety Administration, with the goal of evaluating performance as it relates to safety. This paper describes the system in detail and includes some sample results of the testing. Language: en

Analyzing Kinematic Schemes of Intermediate Axle Central Reducers of Final Drives

Before developing a central reducer of the drive intermediate axle, it is necessary to choose its kinematic scheme to define the most important truck properties. Examples prove that a type of gearing, kinematic scheme and mutual position of gear or worm wheels of the central reducer has impact on the mass of the intermediate axle, placement of the engine and brake mechanisms, and truck configuration as a whole. They also influence on a possibility to use a long-stroke suspension, provide a differential connection between axles, and a torque transfer to the next axle. The work analyzes various schemes of the intermediate central reducers using one or two pairs of gear or worm wheels. It defines the ways to provide normal operating conditions for the engine drive line of the non-intermediate axle. The paper shows that, in most cases, the two-shaft transfer cases with a coaxial or non-coaxial arrangement of the output shafts, connected in front of or behind a conical or hupoid reducer, allows implementation of intermediate reducers. According to a set of properties, for the trucks equipped with a dependent or independent long-stroke suspension, the most rational is the hub-reduction final drive with helical-bevel and conic central reducers, respectively, in intermediate and non-intermediate axles. To apply double helical-bevel central reducers in intermediate and non-intermediate axles is expedient if it is necessary to ensure unification of crankcase parts of axle, improve protection, and raise a driveshaft durability of the non-intermediate axle drive. The paper presents the most rational schemes for three drive axles to be group-driven. Creating a three-axis group-driven cart is possible to implement by setting one more axle in front of the two-axis cart, with central reducer of this axle having the same scheme, as a reducer in the intermediate axle of the two-axis cart. Thus, in case of differential connection between axles and identical vertical loads towards the axles in the central reducer of the first axle of the tridem drive axles it is necessary to use the asymmetrical inter-axial differential, unlike the central reducer of the second intermediate axle of the same cart where the symmetric inter-axial differential is set.

Analysis of Data on Heavier Truck Weights

Knowledge of truck axle weights and distribution is critical for assessing the damaging effects of loading on pavements. A study was initiated in Wisconsin to investigate the impact of a new law that allows vehicle combinations up to 98,000 lb on six axles to transport raw forest products during the spring thaw suspension period. Analysis of truck weight data collected at two logging industrial facilities was done to determine whether certain logging trucks were more damaging than others. The data collected included truck axle weight and spacing from platform scales at two logging industrial facilities, plus scale operators' monthly supplied log truck reports covering the period of December 2011 to May 2012. Analysis revealed that a considerable proportion of trucks were overloaded at the two facilities, with overload averaging 31% and 24% in winter and 25% and 33% in spring. The magnitude of the overload, however, averaged less than 5% of the 98,000-lb limit permitted under the law for gross vehicle weight. FHWA Class 9 loaded trucks produced a higher damage factor compared with that of Class 10 loaded trucks. In addition, Class 9 loaded trucks resulted in a lower average relative log carrying efficiency of 15,400 lb per equivalent single-axle load compared with 22,000 lb per equivalent single-axle load for Class 10 loaded trucks. Better truck configuration choices can benefit both the industry and the highway agency by allowing the industry to haul more logs while inflicting less damage to the pavement.

Controlling moisture content and truck configurations to model and optimise biomass supply chain logistics in Ireland

In the coming years, Ireland will continue to face an increasing demand for wood biomass as a renewable source of energy. This will result in strained supply/demand scenarios, which will call for new planning and logistics systems capable of optimizing the efficient use of the biomass resources. In this study, a linear programming tool was developed which includes moisture content (MC) as a driving factor for the cost optimisation of two supply chains that use short wood and whole trees from thinnings as material feedstock. The tool was designed and implemented to analyse the impact of moisture content and truck configurations (5-axle and 6-axle trucks) on supply chain costs and spatial distribution of the supply materials. The results indicate that the inclusion of wood chips from whole trees reduces the costs of wood energy supply in comparison with only producing wood chips from short wood to satisfy the demand, with 9.8% and 10.2% cost reduction when transported with 5-axle and 6-axle trucks respectively. Constraining the MC of the wood chips delivered to the power plant increases both transport and overall supply chain costs, due, firstly to an increase in the haulage distance and secondly, to the number of counties providing the biomass material. In terms of truck configuration, the use of 6-axle trucks resulted in a 14.8% reduction in the number of truckloads and a 12.3% reduction in haulage costs in comparison to the use of 5-axle trucks across the MC scenarios analysed.

Analysis of truck cabin egress motion

The purpose of this work was to analyse truck egress motions in order to simulate them using a digital human model (DHM). Eight subjects participated in the experiment. Twelve truck configurations were tested using an adjustable mock-up. Ingress and egress motions were recorded using an opto-electronic system, synchronised with force sensors to measure contact forces. The motions were reconstructed for a commercial DHM tool by inverse kinematics. The beginning of egress motion was analysed. Motion coordination was investigated thanks to contact diagrams of hands and feet. Two foot strategies (FSs) were observed according to which foot reached the highest step. Four major hand strategies (HSs) were defined according to when the hands moved down along the handles. FSs and HSs were found to be subject specific, but could change depending on the truck configuration.

Evaluation of fatigue and rut damage prediction methods for asphalt concrete pavements subjected to multiple axle loads

The new Mechanistic–Empirical Pavement Design Guide (MEPDG) developed under NCHRP 1-37A does away with the American Association of State Highway and Transportation Officials-derived equivalent single axle load concept and calculates damage caused by various axle configurations directly. However, the calculation of pavement damage caused by multiple axles (tandem, tridem, etc.) is significantly affected by the summation method used to describe the response of the pavement due to the passage of a given axle type or truck configuration. In this paper, the results from different methods of accounting for the passage of a given axle group are compared using laboratory fatigue and rut data from repeated cyclic load tests. The evaluation criterion for these different summation methods was the degree of agreement with the measured laboratory performance. The results show that for fatigue damage, dissipated energy and strain area methods have an excellent agreement with the laboratory values, whereas peak and peak mid-way methods have poor agreement. This implies that it is important to consider the entire strain pulse when calculating fatigue damage under multiple axles. For rutting damage, the peak strain method has the best agreement with the laboratory values, whereas dissipated energy and peak mid-way methods underestimate the rutting damage. Finally, the MEPDG procedure for calculating the strain under multiple axles considerably underestimates the damage for both fatigue and rutting. However, model calibration in the MEPDG does improve the prediction of the damage due to multiple axles for fatigue and to a lesser extent for rutting.

Spatial Investigation of Mineral Transportation Characteristics in the State of Washington

This study investigates the spatial relationships between construction aggregate shipments and the per axle payload weights of trucks as they pertain to highway deterioration in the state of Washington. A previous study investigated the transportation characteristics of mined aggregates using a spatial autoregressive model, where a significant positive relationship between payload weights and shipment distances was established. This paper expands the previous study by assessing the contribution of aggregate hauling trucks to pavement deterioration using per-axle loads by truck configuration. Results showed a positive relationship between weights per axle load and several shipment distance categories. According to the well-established per axle weight and pavement damage relationship, incremental changes in per axle payload weights resulting from longer shipment distances clearly suggest that longer haulage increases the magnitude of pavement deterioration. This direct relationship between road impact and the distance hauled emphasizes the importance of the proximity of mine sites to different end users.

Economic evaluation of a roll-off trucking system removing forest biomass resulting from shaded fuelbreak treatments

Shaded fuelbreak treatments involve removal of understory brush and small-diameter trees to reduce fire hazards by disconnecting the continuity of fuels. As a result of these treatments, woody biomass (referred to as slash) is piled throughout the treated stand and later burned. Mechanical removal of slash has not been successfully implemented in many areas due to limited accessibility to sites and the high costs associated with collection and transportation of slash. To address these issues, a roll-off truck paired with a small skid-steer loader was used to collect and transport slash to a centralized processing site where slash was ground as hog fuel for energy production. “Roll-off truck” refers to a straight frame truck configuration in which a 30.6-m3 container is rolled onto and off the straight frame truck by means of a truck-mounted winch system. This study was designed to quantify the operational performance and costs of removing slash piles using a roll-off trucking system in mountainous conditions in northern California. The overall cost to collect and haul hand-piled slash was $26.81/tonne with 22% average moisture content or $34.37/bone dry metric ton. The roll-off trucking system should be used primarily for short hauling distances since trucking costs significantly increase with small increases in hauling distance due to slow traveling speeds and low slash weight being hauled. Financial analysis indicated that contractors can receive high rates of return on their invested capital after accounting for inflation and income taxes, but limited work opportunities are a concern for them.