 Skid resistance of road surfaces is an important safety parameter. Decreasing skid resistance correlates with increasing number of accidents.  Skid resistance is one of the substantial factors which ensure safe travelling on automobile roads. Because of poor road safety situation, old vehicle fleet and many vehicles that are driven with old or outworn tyres there is a need to improve safety situation. Road pavements with high and long-lasting skid resistance could be a solution.  Developing pavements with high skid resistance it is essential to develop harmoniously from tyre and road contact noise and rolling resistance point of view. All these characteristics are important and related with road surface texture.  This apparatus measures the skid resistance between a rubber slider (mounted on the end of a pendulum arm) and the test surface. This provides highway engineers with a routine method of checking the resistance of wet and dry surfaces to slipping and skidding, both in the lab and on site.  The British Pendulum Skid Resistance Tester is an impact type pendulum used to measure the energy loss when a rubber slider edge is propelled over a test surface. The values measured represent the frictional properties and are expressed as BPN (British Pendulum Number).

1. P. Vineeth Kumar
KEC-041

2. BRITISH PENDULUM SKID RESISTANCE TEST EQUIPMENT

3. Contents
Basic Definitions
Factors affecting skid resistance
Preparation of apparatus
Working principle
User Instructions
Applications

4. Skidding
In skidding phenomenon, the distance travelled by wheel on the road
is more than the circumferential movement. When brakes are applied,
wheels get locked and still if the vehicle moves ahead, longitudinal
skidding is said to occur.
Slipping
In slipping, the distance travelled by wheel on the road is less than the
circumferential movement. If the wheels of the vehicle are rotating but
the vehicle is not moving forward, then slipping is said to occur.

5. FACTORS AFFECTING SKIDDING RESISTANCE
Condition of Tyres
Effect of Road Temperature
Effect of Water
Type of aggregate

6. APPARATUS
Levelling screws
Scale
Drag pointer
Locking and control knobs
Frictional rings
Water container
Surface thermometer and
Brush

7. PREPARATION OF APPARATUS
Levelling
Zero adjustment
Slide length adjustment

8. Working principle
A pendulum rotates about a spindle attached to a vertical pillar. At the
end of the tubular arm a head of known mass is fitted with a rubber
slider.
The pendulum is released from a horizontal position so that it strikes
the sample surface with a constant velocity.
The distance travelled by the head after striking the sample is
determined by the friction of the sample surface. A reading of Skid
Resistance is obtained.

9. User Instructions
Testing should be carried out in accordance with the relevant standard
or guidelines.
Wipe all flooring materials received for testing in the laboratory, with
a clean, dry paper towel to remove all dust prior to testing.
It is necessary that at the time of testing the flooring material is flat
and securely fixed so as to avoid movement of the sample during
testing.

10. Applications
Road surface testing.
Testing of new road surface materials under development.
Testing of aggregates in the PSV (Polished Stone Value) Test.
Testing of floors and pedestrian walkways.
Flooring materials product development.
Accident investigations, both traffic and pedestrian.
Testing of pavers, in the Flat Bed Polisher.