Description
General
ViaFriction Winter is a one-wheeled friction measuring device pulled by a vehicle. It is designated a CFME (Continuous Friction Measuring Equipment). Its main task is to measure the friction of the pavement surface in winter conditions. The friction between the measuring wheel and the surface is continuously measured, while a unique measuring technology, developed and patented by ViaTech, ensures that the data is stable and reliable, even under volatile conditions. This reduces the need for calibration significantly.
Winter measurements will expose the device to low temperatures, salt, gravel, etc. ViaFriction is built from the highest-quality materials and components to ensure optimal results, even in the unforgiving winter environment. The heat that ViaFriction produces under operation will keep the device free of ice and snow.
The device has very few moving parts — which makes ViaFriction less prone to mechanical failure.
Over 200 ViaFriction devices have been delivered since 2006 and most of the devices are still being used to make the winter roads safe. This is a testament to their durability. ViaFriction uses an electric braking system to be able to measure the friction coefficient. This system doubles as a heating device, reducing the ice and snow that may deposit on the device.
Through rigorous testing, it has been proved that ViaFriction has superior characteristics compared with other friction testers on the market. ViaFriction gives repeatable measurements for various conditions and retains its calibration over time. Our customers range from universities to road authorities and private companies around the world.
The device will run freely behind the vehicle under transport. It may also be delivered with an electric lifting device, which will elevate ViaFriction over the road surface when not in use. See the images for an illustration of this lifting mechanism.
ViaFriction Winter is normally delivered as trailer solution. The device is then powered from the trailer connection. ViaFriction communicates with the computer in the car using a wireless link or an Ethernet cable. The trailer solution makes the friction meter independent of one specific vehicle and does not require vehicle-specific installation.
Standard winter device
Technology
The measured friction and friction force depends on the normal force on the measure wheel, and the speed difference in between the measure wheel and the vehicle. In order to obtain accurate measurements, it is important to have an accurate control of the speed and a good measurement of the normal force.
Most friction testers currently on the market have a fixed speed difference in between the measure wheel and the vehicle. ViaFriction uses an electrical brake to control the speed of the measuring wheel. The brake is controlled by a computer. This solution results in a control system with extremely low response time and an accurate control of the speed of the measuring wheel. It also allows measurement modes not possible for devices on the market today. This includes the important Surveillance Mode, that can find low friction areas without having to brake the wheel all the time. This significantly reduces wear on the wheels and system.
An advanced suspension system ensures that the measure wheel has a good grip on the road surface, even on uneven roads.
Winter measurement
Winter measurements will expose the device to low temperatures, salt, gravel, etc. ViaFriction is built from the highest-quality materials and components to ensure optimal results, even in the unforgiving winter environment. The heat that ViaFriction produces under operation will keep the device free of ice and snow.
Running during the winter does not require the watering system explained above. As such, the device can be delivered as a winter-only version, without this system. The small winter-trailer is accredited by the Norwegian Road Authorities.
Measurement Modes
ViaFriction supports several measurement modes such as fixed slip, variable slip and surveillance.
Fixed slip
The fixed slip mode is when the measure wheel speed is a percentage of the vehicle speed. This is identical to measurement modes used by most friction testers. In order to obtain repeatable results in fixed slip, the measurement must be performed in a fixed speed. The measured friction varies with the speed difference in between the measure wheel and the vehicle.
Surveillance
The surveillance mode is a variant of the fixed slip mode where the actual friction measurement does not take place unless the friction level is below a given value. The surveillance mode greatly reduces wear on tire and apparatus.
User Interface
The driver operates the ViaFriction friction tester using a Windows PC program on a lap-top. The program can, in addition to the normal PC interface, be operated using a small button panel mounted close to the steering wheel. The measurements can be transferred via mobile broadband from the vehicle to the decision-makers in real-time to ViaWEB. These measurements can then be analysed using ViaPlot+ or Microsoft Excel. Recording of friction measurements is often combined with ViaPhoto for documentation of the road standard and executed maintenance work.
Technical specifications
| Physical dimensions | |
|---|---|
| Dimensions (with winter trailer) | Height: 830 mm, Length: 2030 mm, Width: 1790 mm (32.7, 79.9, 70.5 in) |
| Dimensions (friction meter only) | Height: 830 mm, Length: 1150 mm, Width: 405 mm (32.7, 45.3, 15.9 in) |
| Weight (with winter trailer) | 180 kg (397 lbs) |
| Weight (friction meter only) | 80 kg (132 lbs) |
| Measurement speeds | |
| Measurement speed: | 20 – 95 km/h (12 – 60 mph) |
Fixed Slip
The slip percent can be set to any percentage from 1% to 75%. Typically slip percentage during measurements is 20% under winter conditions and 18% under summer conditions.
