However, disadvantages include insufficient accuracy for vehicle weight accuracy (loads can vary up to ±15%). While this technology can be used to distinguish between loaded and empty trucks, it is not accurate enough to be used for accurate inspection of loaded trucks to determine which ones are overweight. In addition, this technology is very sensitive to plate failure. The lifetime of the devices is shorter than some of the more expensive WIM technologies, with the piezoelectric system having a lifespan of about 4 years. In addition, the durability of the road surface affects the longevity of the technology. The single load cell scale consists of two weighing platforms with an area of 6` x 3`2″, arranged side by side to completely cover a standard 12` track. A single hydraulic load cell is installed in the center of each platform to measure the force exerted on the scale. Load measurements are recorded and analyzed by the system`s electronics to determine axle loads. With proper installation and calibration, a piezoelectric WIM system should provide a gross vehicle weight within 15% of the actual vehicle weight for 95% of the trucks measured. In bad weather, in the mountains or in unique road conditions, such as driving on gravel or sand, it may not be safe to work with the legal maximum weights.
Consider this before you drive. Plug & Play sites and roaming sites have a variety of configurations. They are used to conduct short-term enforcement actions with a relatively small budget. However, once members of the commercial vehicle industry who operate illegally learn where a non-fixed weighing point is in operation, they can either divert their routes or park and wait for the non-fixed weighing station to close – usually only a few hours. (b) The vehicle or combination of vehicles may be determined by adding the weights obtained while all the individual components are simultaneously based on more than one weighing platform. The basic structure of the typical piezoelectric WIM sensor consists of a copper strand surrounded by piezoelectric material and covered with a copper casing. When pressure is applied to the piezoelectric material, an electrical charge is generated. The sensor is actually integrated into the pad and the load is transferred through the pad. The properties of the pad (level approach, temperature, etc.) therefore influence the output signal. By measuring and analyzing the load generated, the sensor can be used to measure the weight of a passing tire or group of axles.
The Piezoquart or Kistler WIM system consists of a lightweight metal profile in the middle of which quartz discs are mounted under preload. When the force is applied to the surface of the sensor, the quartz discs emit an electrical charge proportional to the force applied by the piezoelectric effect. A charge amplifier converts this electrical charge into a proportional voltage, which can then be processed as needed. Whether you load and secure the load yourself, you are responsible for: Federal, state, and local regulations regarding commercial vehicle weight, load securement, load coverage, and where to drive large vehicles vary from place to place. Know the rules of where you are going to drive. There are several approaches to performing 3D imaging, which can include both side readers and aerial readers, as the accuracy of the image depends on the angle of installation of the laser reader. While this technology cannot determine a vehicle`s weight for law enforcement purposes, it can identify commercial vehicles that exceed legal width restrictions. As mentioned earlier, while there are no height restrictions at the federal level, most states impose enforceable height restrictions ranging from 13.6 feet to 14.6 feet (USDOT, FHWA, 2014b). The data collected by these systems can provide speeds, weights, time of day, vehicle identification, motor carrier identification, vehicle height, vehicle length, indication of brake malfunction, status of motor carrier operating references, identification of stolen vehicle (license plates), and assistance with Amber Alerts, Silver Alerts or BOLO (Be on the Watchout) criminal alerts. The installation of a single weighing cell scale requires the use of a concrete vault. The pavement is cut and excavated to form a pit.
The frame is positioned in place and then poured into concrete to form a safe and durable foundation for the scale. The required vault size measures 165″ x 58″ by 38″. The single load cell scale is usually installed in a lane with two inductive loops and an axle sensor to provide information about the length and centre distance of the vehicle. A complete installation of the scales, loops and axle sensor in a single lane can be carried out in 3 to 4 days. As shown in Table 5, enforcement activities in all countries do not represent the total cost of TSW enforcement. Adjusted for the two states where cost data was not available, the total national cost of TSW in 2011 could be approximately $635 million. When estimating the total costs for all states, the sum is about 6% higher than the sum of the costs reported for 2011 (in 2011 USD). This estimate is calculated by first normalizing each state`s total enforcement costs by dividing them by the total VMT for trucks in that state.
Using the median cost per VMT truck for reporting countries, the total costs in the two non-reporting countries are then estimated by applying this median value to the VMT for trucks in those countries. Prices for portable scales vary and can cost anywhere from $2,000 to $4,700 per device (Hanson, 2014). Law enforcement personnel typically have four portable scales per patrol vehicle, and each scale must be calibrated and certified at regular intervals to ensure accuracy and legality. Annual maintenance costs range from $180 to $425 and include the cost of recertifying scales. You are responsible for not being overloaded. Definitions of weights are as follows: Plug and play locations are places where there is a certain level of infrastructure, but are not used for law enforcement when enforcement officers are not on site.