Halliday Technologies | Roadway RT3 Wet Friction Testing

Roadway RT3 Wet Friction Testing

Wet roads typically have lower friction than dry roads. An RT3 with Water System can answer how much has that friction dropped as you change the water film thickness in front of the measuring tires.

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Customers require a water system when they have wet friction problems on their roads.

The water system allows them to test in a precise way how the tire responds to the surface with the addition of a controlled flow rate of water. To have a controlled flow rate of water is important because a small increase in flow rate can dramatically change the friction results on some surfaces.

A water system can be added to any RT3^® unit. It is tailored to the testing parameters set by the customer. We ask:

Will the host vehicle carry the main water tank?
What is the payload capacity of host vehicle?
How far do you want to test before refilling the tank?
At what film thickness do you want to measure surface friction?
- Typically we test at 0.5mm to 1.00mm film thickness.
For larger water requirements, would you consider a trailer solution where the RT3^® attaches to the trailer and the trailer carries the main water tank?
What type of tires do you want to use to complete the test?

FEATURES

With the RT3^® Curve there are two nozzles one for each measurement tire. For the RT3^® Fixed Hitch there is one nozzle.

The customer can set two desired flow rates. The water flow rate is then activated through the display. By having two flow rate settings, the customer can test two flow rates at the same speed or the same flow rate at two different speeds. The water system activates automatically when the host vehicle reaches a pre-determined speed.

How it works

It is not easy to design a water system that is accurate and has a very consistent flow rate. However, it is imperative for this system to be consistent for the surface friction testing results to be accurate.

We use a two tank system where a main tank feeds a secondary tank. The main tank size is based on the vehicle (trailer) payload capacity and the length of test required before refilling the tank. The secondary tank is much smaller and attaches to the frame of the RT3^® unit or to a customized tow hitch frame we make for the vehicle. Through this dual tank system, changes in water pressure and water movement in the main tank do not affect the results.

The water is pumped from the smaller tank through a flow rate sensor to the nozzle. It is controlled through a custom designed circuit board.

Roadway maintenance – extending the life of your surfaces.

In recent years, more and more companies are introducing new products to extend the life of the roadway surfaces. These products and methodologies can be very effective at extending the life of the surface. However, these products will change the performance of the road surface because they change the micro and macro texture of the surface.

Understanding that change in dry and wet conditions is critical to choosing the best products and managing their application. The RT3^® units have the sensitivity to measure how these products affect the performance of the measurement tire on that surface.

A testing example

In a series of tests we completed for a DOT, we measured the surface friction of older asphalt and two latex sealed sections of pavement. Both sealants were laid at a similar time by two different contractors.

We were able to show that the dry friction increased with a latex seal, but the wet friction was significantly lower on both sections of latex sealed pavement than the older worn asphalt.

With an increase of flow rate from 0.5mm to 0.75mm, the wet friction results dropped significantly in some areas. One of the latex sealed surfaces had much lower friction than on the other. We studied the surfaces and found that the macro texture of the low performing latex surface was filled with the sealant. As a result, the water was not displaced and so the friction dropped in those areas.

Please do not interpret this example as latex sealants will not work. We do not have the data to support that conclusion. What we can say is that with the RT3^®, you will understand how the surface friction changes based on what you do to it. Also, the RT3^® will allow you to objectively measure how that surface friction is changing overtime.

Halliday Technologies is committed to promoting environmental sustainability.

We choose each product in the manufacturing process to be durable. Ensuring the RT3^® is built to last, we can drive down life cycle costs for our customers. Additionally, through objective and reliable data, our customers can reduce their chemical and salt usage during winter events by optimizing their treatment approach.