Truck Axle Weights Research Articles

Generalized Method and Monitoring Technique for Shear-Strain-Based Bridge Weigh-in-Motion

AbstractDevelopment and testing of a new type of bridge weigh-in-motion system (BWIM) based on the measurement of shear forces near the supports of the bridges is described. The proposed system is applicable to both determinate as well as indeterminate bridges. Fiber-optic Bragg grating rosette sensors were used in this approach. Formulations are based on the establishment of shear influence lines in terms of axle weights and spacings. The system further involves calibration for the estimation of a bridge parameter α, which is a function of the cross-sectional and material properties of the bridge. Three different bridges, one box-girder prestressed concrete bridge and two concrete-slab-on-steel-girder bridges with different span lengths, were instrumented for the evaluation of the proposed BWIM system. Field implementation involved a series of truck runs for calibration and evaluation of the BWIM system. Measured and actual truck-axle weights, spacings, and axle speeds as well as the gross vehicle weight...

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.

Evaluation of accuracy of weigh-in-motion systems in Alberta

Weigh-In-Motion (WIM) systems can collect a variety of traffic data for moving vehicles. The accuracy of six piezoelectric WIM systems installed in Asphalt Concrete (AC) pavements at six highway locations in Alberta was investigated in a five-year verification experiment, which compared the WIM measurements to predetermined axle weights of a test truck. While the WIM systems accurately characterized the speed and dimensions of the test truck, 56, 43, 37, and 34 percent of their weight measurements for single steering, tandem drive and load axles, and Gross Vehicle Weight (GVW), respectively did not comply with the American Society for Testing and Materials (ASTM) E1318 requirements. Outlier analysis revealed that an error limit of 50 percent can be considered as the threshold for the WIM random errors. Mechanistic Empirical Pavement Deign Guide (MEPDG) was used to investigate the effect of the WIM errors in measuring the test truck's axle weights on flexible pavement design for a typical section in Alberta. While WIM errors in the range of ±20 and ±30 (corresponding to the majority of WIM errors in Alberta) did not affect the AC design, error magnitudes of ±50 and ±100 percent affected the AC thickness by more than 100 percent.

The single container loading problem with axle weight constraints

Abstract This paper considers a single container loading problem with practical constraints that address the U.S. legal requirements stipulated in the California Vehicle Code (CVC) related to truck axle weight. The problem is computationally intractable for practical problem cases. We propose an integrated heuristic solution approach that combines a GRASP wall-building algorithm with linear integer programming models. Experiments are conducted using data generated from real cases showing the effectiveness of our approach. This work has been developed into a software component to facilitate decision makers in the industry.

Measurement of Truck Axle Weights by Instrumenting Longitudinal Ribs of Orthotropic Bridge

The longitudinal ribs of an orthotropic box-girder bridge were instrumented to measure axle weights of trucks. The bending stress in the longitudinal rib is composed of a girder component, i.e., the flexural stress due to the rib’s function as part of the box-girder’s upper flange in carrying vehicles, and a rib component, i.e., the part of stress produced in the rib when it is viewed as a continuous beam supporting wheel loads. The instrumentation locations were set close to the middle support of the two-span continuous bridge to reduce girder component and impact effect. All possible wheel-supporting ribs inside the box girder were instrumented to cover most transverse locations of truck wheels. Deviating passes as well as central passes were carried out for each traffic lane in calibration tests to catch maximum stress response. The results of the calibration tests were used to solve the influence lines of the girder component and rib component at each strain gauge. With these influence lines, the rib component was separated from girder one in the stress waves of the 3-day live traffic measurements, and axle weights of the truck traffic were subsequently calculated.

Methodology to Assess Impacts of Alternative Truck Configurations on Flexible Highway Pavement Systems

Assessing the appropriateness of truck axle weight limits and truck configurations from the standpoint of the impact on infrastructure is a critical issue in the determination of North American truck size and weight harmonization. A methodology is discussed for determination of pavement response, estimation of load equivalencies, and development of performance curves for different cases of flexible highway pavement and heavy-vehicle interactions for normal environmental and thaw conditions. The pavement response model uses the MSC Software Corporation’s general-purpose finite element program, MSC.MARC. Seven different truck configurations, using North American axle weight limits, are used to illustrate the impacts of alternative truck configurations on flexible highway pavement systems. Three progressive schemes are employed for impact assessment: the truck-factor scheme, the repetitions-to-failure scheme, and the tonnage-over-life scheme.

Allocation of Pavement Damage Due to Trucks Using a Marginal Cost Method

A procedure was developed for quantifying the pavement cost of proposed changes in regulations governing truck weights and dimensions, particularly the marginal cost method used for pavement cost allocation. The procedure was part of a comprehensive study undertaken by the Ontario Ministry of Transportation in response to government and industry initiatives to harmonize Ontario’s truck regulations with those in surrounding jurisdictions. The marginal pavement cost of truck damage was defined as a unit cost of providing pavement structure for one additional passage of a unit truckload (expressed as equivalent single axle load). The results indicate that the highway type (or truck volumes associated with the highway type) has a major influence on marginal costs. For example, the annualized pavement life-cycle cost of the passage of one additional typical truck on 1 km of a highway in southern Ontario can range from about $0.004 for a freeway to $0.46 for a local road (Canadian dollars). The marginal cost method can be used to quantify pavement damage due to any axle load combination for both new and existing, in-service pavements. The knowledge of marginal costs would enable highway agencies to quantify the impact of specific regulatory changes of truck axle weights on pavement costs; for example, to quantify the pavement costs associated with increasing allowable truck weights of logging trucks on a specific segment of the highway network.

SITE-SPECIFIC TRUCK LOADS ON BRIDGES AND ROADS.

Condition assessment of bridge structures, prediction of remaining life and evaluation of pavement performance and behaviour require knowledge of load and resistance statistical parameters. The present study addresses the need for the determination of live load on bridges and roads, and in particular the site-specific variation of the live load statistics. Truck loads were measured under normal traffic conditions at selected bridges located on interstate highways, state highways, US highways and surface streets using a bridge weigh-inmotion (WIM) system. Truck data is also available from highway weigh station logs and citation files. Stationary weigh station data is biased and may not accurately reflect the distribution of truck axle weights, axle spacing, and gross vehicle weight. Citation data is helpful in understanding the nature and extent of overloaded trucks; however, it will not be representative of the normal traffic distribution. WIM measurements of trucks can be taken discretely during normal traffic conditions, resulting in unbiased data for a statistically accurate sample of truck traffic travelling a particular highway. Results of the present study show that truck loads are strongly site specific. In addition, there is a negative correlation between law enforcement effort and the occurrence of overloaded trucks. Overloaded trucks are observed on roads not controlled by truck weigh stations. A comparison of the weigh station data, truck citation data and WIM measurements obtained in this study confirms this observation.