Road Skid Tests Explained

Road Skid Tests Explained

Posted: 28th February 2019

Posted by: The National Testing Team

Road Skid Tests

There are many dangers on the road putting users at risk of accidents and potential serious harm. With 165,100 road casualties recorded in the year 2017/2018 across Great Britain it’s important that local councils and highway agencies have an obligation to minimise dangers wherever possible to provide safe roadways.

A common hazard for road users is the risk of skidding which is one of the leading causes of serious accidents and injuries. Ensuring adequate skid resistance on road surfaces can ultimately reduce incidents of skid related accidents occurring and aid in keeping road users safe.

It is therefore extremely important that roads and paved surfaces are regularly tested - in the UK there are three main methods used to assess skid resistance of various roadway materials which include SCRIM, GripTester and the Pavement Friction Tester.

Pavement friction tester

Pavement friction can deteriorate for many reasons such as weathering, aging and due to high volumes of traffic. The pavement friction tester assesses and identifies any areas that have a decline in friction and ensures that surfaces are of a high quality resistance. This method measures both fully locked wheel and peak friction on paved surfaces.

Pavement friction testers use modern electronic systems to operate, and are able to store multiple test results. The program calculates the Skid Number and Peak Braking Coefficient and records these in real time. Because of the sophisticated digital systems, pavement friction testers are extremely accurate in measuring distances and speeds. You can view the friction and speed data for each test on the display, and print these out to incorporate into reports if desired.

SCRIM testing

SCRIM stands for Sideway-force Coefficient Routine Investigation Machine and is used to measure wet skidding resistance on road surfaces. It is a popular choice of skid resistance testing, not only in the United Kingdom, but across the world too.

Depending on the type of road surface, the SCRIM machine has a daily survey capacity of 200 to 300 km. There are also two options for the target test speeds: 50km/h and 80km/h. The permitted speed range covering these target speeds is 25 to 85 km/h. When skidding resistance data is recorded within this range of speed, it can be speed corrected to give corresponding values at 50km/h.

GripTester surveys

Another internationally recognised friction measuring device, used for analysing and surveying road ways, is the GripTester. This test is also recognised by UK Civil Aviation Authority for having the ability to test friction in airfields.

There are multiple situations in which the GripTester would be able to support maintenance or investigations; from comparing sites before and after restoration to measuring skid resistance at road accidents. The GripTester evaluates the friction of the surface, identifying areas in need of repair to minimise the risk of skidding.

There are models available that assess the microtexture of a road surface and correlate a GripNumber which can then be easily converted to the SCRIM equivalent; a user friendly quality to lessen difficulty in evaluating the results.

User safety is the most crucial aspect for construction practices to consider when developing and maintaining road ways. Skid resistance measuring devices are the way forward in providing safer roads and reducing skid related accidents. Not only that but they can accommodate to, and evaluate, many types of materials.

For more information and advice on what type of test to carry out on pavements, roads and highways in your area, call our friendly and professional team at National Testing. We have a vast amount of knowledge and experience working with local councils, ensuring roads are fit for purpose. We can recommend the best suited friction measuring device for your business to ensure skid resistance is at its peak.

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