4/29/2023 0 Comments Trucks blown over i39Furthermore, exceptions exist such as higher axle weight limits for vehicles carrying agricultural products or implements, forestry products, or milk products. For example, in Wisconsin the maximum weight of a group of two or more axles (tandem or greater) is determined based on the spacing between the first and last individual axle within the group. The precise size and weight limits depend heavily on the regulations adopted in each individual state, and numerous exemptions and variations in weight limit formulas often exist. The most common weight limits include 88.96 kN (20 kips) for a single axle, 151.24 kN (34 kips) for a tandem axle, and 355.86 kN (80 kips) gross vehicle weight (GVW) the typical dimensional limits include maximum width of 2.59 m (8.5 ft), maximum height of 4.11 to 4.27 m (13.5 to 14 ft), and variable maximum length limits, depending on the vehicle and axle configuration. Typically, states’ size and weight limits are based on federal limits adopted for the interstate highway system. In the United States, individual states have the authority to issue permits to oversize and overweight (OSOW) vehicles exceeding national and state size and weight limits. Pavement damage was investigated through field studies of the selected highways, generation of site-specific OW permit vehicle ALS using a comprehensive database of single-trip permits issued in Wisconsin, and comparative pavement performance analyses using AASHTOWare Pavement ME Design software. The results of a comprehensive OSOW single-trip permit mapping effort were used to identify state highway segments with high levels of OW truck traffic. The objective of this research is to characterize the relative contribution to pavement damage and deterioration induced by single-trip OW permit truck traffic on selected asphalt pavements test sections in Wisconsin. Because pavement deterioration predictions in the AASHTOWare Pavement ME Design models are dependent on detailed traffic and ALS data, determining site-specific ALS variations-especially with regard to the heaviest vehicles-is a crucial step in performing accurate analyses. With the implementation of AASHTOWare Pavement ME Design techniques within the past decade, a new avenue has opened for researching the effects of variations in traffic and axle load spectra (ALS) scenarios on pavement performance. Of particular concern to pavement professionals are overweight (OW) vehicles, which frequently use additional axles and higher-than-normal axle loadings during the transport of heavy loads. With increasing numbers of oversize-overweight (OSOW) vehicle permits issued across the United States as the economy continues to grow, increased scrutiny is being applied to the infrastructure impacts of OSOW vehicles and to the assessment of vehicle size and weight programs from a policy perspective. However, due to the small proportion of OW vehicles relative to the overall traffic levels, the OW vehicles were generally predicted to cause up to ten times the per-truck damage as compared with a typical legal-weight truck, depending on the distress mode and the test site. The proportion of pavement damage and deterioration attributable to OW truck traffic was predicted to constitute a relatively minor proportion of total deterioration, with most distress indices showing relative increases of approximately 0.5% to 4%, with a few outliers. The predicted total pavement deterioration levels from the AASHTOWare Pavement ME Design software were generally consistent with the levels of deterioration observed. OW axle load distributions were developed and integrated with baseline truck traffic levels to develop axle load spectra and other traffic input parameters for the ME pavement analysis. The use of mechanistic-empirical (ME) pavement analyses provided a methodology for estimating the proportion of pavement deterioration attributable to OW truck traffic. Comprehensive analyses were conducted to evaluate pavement performance due to normal traffic loads as well as normal traffic loads plus the OW truck traffic loads. The research included field work (traffic counts and visual pavement surface distress surveys) and AASHTOWare Pavement ME Design. Four Wisconsin highways were selected for investigation due to high levels of OW truck traffic. A database of overweight single-trip permit truck records was analysed to produce a network of Wisconsin corridors heavily travelled by OW trucks. This study investigated the impacts of overweight (OW) permit truck traffic on flexible pavement performance in Wisconsin using field investigation and analysis utilizing the AASHTOWare Pavement ME Design software.
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