Roll dynamics and tyre relaxation in heavy combination vehicle models for transient lateral manoeuvres

Abstract. Long combination vehicles are the future of road transportation. They have much better energy and transport efficiency compared to traditional transport vehicles. There is a huge interest in using long combination vehicles for transporting goods in Sweden. In Finland, long combination vehicles (34.5 m, 76 ton) were introduced to the roads in the end of January 2019. In Sweden, performance based standards, or PBSs, are becoming an accepted tool for evaluating LCV’s safety and transport efficiency. The goal of this thesis is to produce the simplest possible vehicle models, for the performance based standards that concern lateral dynamics. These models will be used to evaluate those performance based standards, with a minimum number of parameters. The models should include lateral dynamics, roll dynamics due to high load and tyre relaxation. Non-linear tyre model will also be implemented to the simulation models. In simulations, single lane change manoeuvre was used to evaluate the performance of the created vehicle models. The finalized models were validated against high-fidelity models from Volvo GTT. The models were created in Modelica language and implemented to OpenPBS library

Modelling and assessment of performance based standards for high capacity vehicles

Abstract. Interest in High capacity transports (HCT) has increased due to better transport efficiency and saving potential in CO2 emissions. HCTs are already allowed on the specified parts of the roads in Sweden (74 tons, 25.25 metres) and longer combination vehicles (30–35 metres) are being considered. The assessment of HCTs could be based on performance based standards (PBS). PBSs are performance requirements on the vehicle to ensure their safe operation on the roads. In Sweden, there are two existing tools for evaluating performance of HCT vehicles with respect to PBS. The goal of this thesis is to help the research project “Performance Based Standards II” to further develop the assessment tool OpenPBS and compare it with the other existing PBS tool. For the comparison, OpenPBS was modified to use the same input parameters as the other tool. Also, the manoeuvres and fixed simulation parameters were aligned, and the same tyre model was used. According to this thesis, OpenPBS would be the more suitable tool for evaluating HCT vehicles than the other tool. Motivation for OpenPBS is the stronger physical base for the modelling, thanks to Modelica format. For instance, future vehicle combinations should be easier to support. However, it should be mentioned that OpenPBS is a more advanced tool due to object orientation and therefore requires more competence in physical modelling

The Potential for Performance-Based Standards as the Basis for Truck Size and Weight Regulation in the United States

This research project examines truck size (dimensions) and weight regulation in other countries, worldwide, to identify size and weight regulations that are based on standards of truck performance. Such standards, known as performance-based regulations, are intended to ensure that the allowable size and weight of trucks is governed by safety standards and/or by standards for infrastructure (pavement and bridges) wear. The primary goals of this study were to identify performance-based size and weight regulatory practices from a widely diverse group of 32 jurisdictions worldwide, to determine the applicability of such standards in the United States (U.S.) size and weight regulatory framework, and to identify the barriers to adopting this type of approach to truck size and weight regulation. Even though adopting some performance-based standards may be difficult, the concepts underlying them offer too many advantages not to move forward and use a performance-based framework as a foundation for future size and weight reform. The experiences in other countries such as New Zealand and the European Union indicate that performance-based size and weight regulations can be successfully developed and enforced. However, due to the size of the U.S. road network and the population of the U.S. heavy vehicle fleet not all standards used in other countries may be successfully implemented in the U.S. size and weight regulatory framework

Degree of Vehicle Overloading and its Implication on Road Safety in Developing Countries

The phenomenon of vehicle overloading is not new and has been discussed in relation to the adverse effects on road pavement damage, road safety and GHG emission. Although much has been said in the context of the more developed countries, there has not been much discussion on vehicle overloading in developing countries. In this study, the extent and degree of vehicle overloading in a developing country is established. Half of the 3-axle trucks were found to be overloaded and the degree of overloading is up to 101% of its legal weight limit! The effect of truck overloading on safety is discussed by establishing the relationship between truck stopping distance and gross vehicle weight for a certain travel speed. Comparison between actual overloading data for 2-axle, 3-axle and 4-axle trucks and the stopping distance illustrates the gravity of the situation which needs a comprehensive and effective strategy from the relevant agencies. Keywords: Road Safety, Vehicle Overloading, Traffic Accidents, Weigh-in-Motion, Stopping Distanc

A comparison of directional performance of articulated heavy vehicles

Abstract: With the increase of international logistics supply chains, modular articulated heavy vehicle (AHV) configurations in freight transport are expected to develop rapidly in China. It is in the process to make a decision on Chinese modular AHV configurations, i.e., what modular configuration for AHVs should be firstly developed and deployed? In order to address the issue, two configurations of AHV were evaluated considering the actual transport situations in China. The lateral stability and the maneuverability of the two configurations AHV, i.e., type-A and -B, were examined using multi-body dynamic modelling and simulation. Numerical simulations were conducted to assess the main directional performance measures, i.e., rearward amplification (RWA) and path-following offtracking (PFOT). Simulations show that the RWA measure of type-B is greater than that of type-A in high-speed evasive maneuvers. In contrast, low-speed PFOT of type-A is larger than that of type-B. Type-A is recommended to be developed first due to the following facts: 1) this AHV exhibits better high-speed lateral stability, 2) the low-speed PFOT of this AHV can be enhanced using advanced vehicle safety systems, e.g., active trailer steering. The achieved results may provide useful guidelines for manufacturers to select and develop effective modular configurations for AHVs.Communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

A pro-forma approach to car-carrier design

To mitigate accidents, reduce loss of life and to protect road infrastructure, it is important that heavy vehicles are regulated. Regulatory frameworks can be divided into two main groups: prescriptive and non-prescriptive. The prescriptive regulatory framework is currently the norm in South Africa and the majority of countries worldwide. Road safety in this framework is governed by placing constraints on vehicle mass and dimensions. These parameters can be measured by the law enforcer and if these are found to exceed prescribed limits, the vehicle is deemed unfit for road use. Although such a legislative framework is simple to enforce and manage, prescriptive standards inherently impose constraints on innovative design and productivity, without guaranteeing vehicle safety. An alternative regulatory framework is the performance-based standards (PBS) framework. This alternative non-prescriptive framework provides more freedom and directly (as opposed to indirectly) regulates road safety. Limits regarding overall length and gross combination mass (GCM) are relaxed but other safety-ensuring standards are required to be met. These standards specify the safety performance required from the operation of a vehicle on a network rather than prescribing how the specified level of performance is to be achieved. On 10 March 2014, the final version of the South African roadmap for car-carriers was accepted by the Abnormal Loads Technical Committee. The roadmap specified that, from thereon, all carcarriers registered after 1 April 2013 would only be granted overall length and height exemptions (which logistics operators have insisted are essential to remain in business) if the design is shown to meet level 1 PBS performance requirements. This resulted in an increased demand for car-carrier PBS assessments. One significant drawback of the PBS approach is the time and expertise required for conducting PBS assessments. In this work a pro-forma approach is developed for assessing future car-carrier designs in terms of their compliance with the South African PBS pilot project requirements. First, the low-speed PBS were considered and a low-speed pro-forma design was developed by empirically deriving equations for frontal swing, tail swing and low speed swept path. These were incorporated into a simplified tool for assessing the low-speed PBS compliance of car-carriers using a top-view drawing of the design. Hereafter, the remaining PBS were considered, incorporating additional checks to be performed when evaluating a potential vehicle. It was found necessary to specify a minimum drive axle load in order to meet the startability, gradeability and acceleration capability standards. The required drive axle load was determined as 19.3% of the GCM. It was confirmed that the static rollover threshold performance can accurately be predicted by means of the applicable New Zealand Land Transport Rule method. The study is limited to 50/50-type car-carriers, however the methodology developed will be used to construct assessment frameworks for short-long and tractor-and-semitrailer combinations. The pro-forma approach offers a cost-effective and simplified alternative to conventional TruckSim® PBS assessments. This simplified approach can significantly benefit the PBS pilot project by offering a sustainable way to investigate the PBS conformance of proposed car-carriers

A test procedure for evaluating the obstacle evasion performance of heavy trucks. Final report

Notes: Report covers the period July 1990 - Sept 1991Motor Vehicle Manufacturers Association, Detroit, Mich.http://deepblue.lib.umich.edu/bitstream/2027.42/938/2/82061.0001.001.pd