Weigh in motion system

The paper deals with real-time Multi-Sensor Weigh – In – Motion System (MS-WIM). This system was designed in Poland in a period of 3 years from 2003 to 2006. The embodied system is equipped with 16 piezoelectric load sensors, in the form of narrow 4m long strips, provided by Measurement Specialties. The paper outlines the system structure and its elements i.e. the weighing site, the data acquisition system and data processing software. Experimental tests indicate that the designed MS-WIM system falls in accuracy class B+(7) in the speed range from 30 km/h to 80 km/h.

The authors have initiated in 2013 a group within the Intelligent Transportation Systems Cluster, which brought together Polish government offices, universities, research institutes and commercial companies. Goal of this group is to apply vehicle’s Weigh-in-Motion systems for direct mass enforcement. Practical implementation of this idea is subject to the following conditions: defining detailed procedures for legalization and metrological control of WIM systems (test conditions), and defining technical requirements for such WIM systems. Both problems have been described in the paper.

This paper describes undertaken actions aimed at implementation of vehicle's Weigh-in-Motion systems for direct enforcement. To achieve this goal the authors have initiated in 2013 a group within ITS cluster, which brought together Polish government offices, universities, research institutes and commercial companies. In the paper are presented developed concepts, problems which require solution and the current state of works undertaken for this purpose in Poland.

The basic problems corresponding to the traffic measurements have been presented in the paper. Authors gave the general overview of the parameters and characteristics describing the vehicles and traffic flow. The current sensors’ technologies used in measuring systems has been presented. Moreover the measuring systems used in traffic measurements have been described. Special attention has been paid to the more sophisticated problems like the vehicle’s classification based on the analysis of its magnetic signature and to vehicles’ weigh-in-motion technique. The presented results base on the Authors’ experience in designing and exploitation of the measuring systems equipped with inductive loops and piezoelectric sensors.

The paper deals with multi-sensors high speed Weigh – In - Motion System (MS-WIM). This system was designed in the period of 3 years from 2003 to 2006 and was financed by Polish Ministry of Science and High Education. The estimation of the vehicle’s static axle load, as well as its total mass is the main aim of the weighing process. This estimation bases on the measurement results of the dynamic load exerted by successive axles on the road. The designed system allows estimating the vehicle total mass with the uncertainty determined by relative standard deviation equal to 2%, in the vehicle speed range from 30km/h to 80km/h.

Abstract—While passenger and freight transportation is growing up in developing countries, traffic congestion, accidents and environmental pollution are getting to be a serious concern for policy makers. Using Intelligent Transportation Systems (ITS) has been recently introduced as a main solution to overwhelm the above problems. Since, weigh in motion system (WIM) is known as a very important component of ITS, its usage is increasingly to be applied for axle load enforcement. On the other hand, huge investment in construction and maintenance of pavement lead policy makers to tackle overloading using weigh in motion systems. Installing weight in motion system is a constructive project with high investment in terms of needed special pavement, electronic devices, and data transferring device and human resource to overloading reduction and save pavement condition in proper situation. Following the above mentioned, it is necessary to be a trade-off consideration between pavement cost repairing and installing weigh in motion system. So in this research will be presented on the basis of break-even at the cost of purchase, installation, operating and maintenance costs of the system and saves the cost to repair the pavement as the top model in terms of income. The average overloaded axles under enforcement performed by authorities to tackle overloading is studied a criterion and the proposed model determines the minimum average overloaded axes in which installing WIM would be an economic project. Although, the proposed model is as a parametric pattern, but an installed WIM system has been selected as case study and the number of required enforcement calculated. The results of this study will help decision-makers in the field of transport, as in the operation of WIM to achieve a balance between costs and revenues from it the right decision to take.

Systems which permit the weighing of vehicles in motion are called dynamic Weigh-in-Motion scales. In such systems, axle load sensors are embedded in the pavement. Among the influencing factors that negatively affect weighing accuracy is the pavement temperature. This paper presents a detailed analysis of this phenomenon and describes the properties of polymer, quartz and bending plate load sensors. The studies were conducted in two ways: at roadside Weigh-in-Motion sites and at a laboratory using a climate chamber. For accuracy assessment of roadside systems, the reference vehicle method was used. The pavement temperature influence on the weighing error was experimentally investigated as well as a non-uniform temperature distribution along and across the Weigh-in-Motion site. Tests carried out in the climatic chamber allowed the influence of temperature on the sensor intrinsic error to be determined. The results presented clearly show that all kinds of sensors are temperature sensitive. This is a new finding, as up to now the quartz and bending plate sensors were considered insensitive to this factor.

In 2013 the authors of this article initiated a group within the Intelligent Transportation Systems Cluster which brought together Polish government offices, universities, research institutes and commercial companies, whose goal is to apply Weigh-in-Motion systems for direct enforcement. Implementation of this idea is subject to the two conditions: defining detailed procedures for legalization and metrological control of WIM systems, and defining technical requirements for such WIM systems. This paper presents concepts, formulates problems that require solutions, and shows the current state of work undertaken for this purpose in Poland.

The use of Weigh-in-Motion systems for direct enforcement depends, first of all, on their high and constant accuracy under variable measurement conditions. Among climatic influencing factors, the pavement temperature turns out to be the most significant one. This paper presents a detailed analysis of this phenomenon. An analysis was carried out for two WIM systems fitted with polymer and quartz load sensors. The temperature variability and its influence on the weighing error was experimentally investigated. Certain methods for the correction of the influence of pavement temperature, based on the WIM site temperature model and on the system calibration performed at several temperatures, were proposed. The influence of a non-uniform temperature distribution along the WIM site, which is of particular significance in multi-sensor systems, was considered. Furthermore, the influence of temperature distribution along a load sensor was analysed. The last issue is described for the first time. It was also demonstrated that the multi-point temperature correction, taking the temperature distribution along a load sensor into consideration, enables the weighing error to be limited to the level of 1%–1.5% over a wide temperature range, from -20oC to +30oC.

The paper deals with the problem of auto-calibration of the Weigh–In-Motion systems. The proposed method base on the assumption, that in the traffic stream occur the specific cars, which chosen load parameter is included in the narrow and known interval. The automatic detection of these specific cars allows the system auto-calibration. The initiative simulation tests and their results confirm in author’s opinion effectiveness of the proposed method.