Proceq SRT 5800 Manual page 6

Operation of tester (wet conditions)
1. Wet the road surface and slider, ensuring that the
road surface is free from loose grit.
2. (ii) Bring the pointer round to its stop. Release the
pendulum arm by pressing button C and catch it on
the return swing, before the slider strikes the road
surface. Note the reading indicated by the pointer.
(N.B. if the slider is not wetted as well as the road
surface, the reading obtained on this first swing
should be neglected.)
3. Return the arm and pointer to the release position,
keeping the slider clear of the road surface in this
operation by means of the lifting handle. Repeat
swings, spreading the water over the contact area
with the hand or a brush between each swing (this is
particularly important on smooth surfaces). Record the
mean of five successive readings, provided they do
not differ by more than three units. If the range is
greater than this, repeat swings until three successive
readings are constant; record this value.
4. Raise the head of the tester so that it swings clear of
the surface again and check the free swing for zero
error.
Procedure when testing road surfaces
1. Inspect the road and choose the section to be tested.
2. Set the apparatus on the road surface in the track
chosen to be tested, so that normally the slider swings
in the direction of the traffic. On surfaces bearing a
regular pattern, such as ridged or brushed concrete,
tests should be made with the slider operating at 80°
to the ridges. Take the mean of five readings, as
above, at each of five locations in the test track
(usually the nearside wheel-track) spaced at
approximately 5- to 10-m intervals along the length
under test. The mean of these readings gives a
representative value of the skidding resistance of the
road.
3. The slipperiness of some roads varies considerably
across the width of the road and sometimes the crown
of the road is the most slippery part. Where this is
suspected, tests should also be made on the crown of
the road.