Specifications

12 LTL-X Retrometer DELTA
Important guide lines for the correct use of the LTL-X
Positioning of the instrument on the road marking
Select an area of the pavement marking that is level when taking readings. The red dot on the
side of the base cover indicates the center of the measurement field on flat markings. The
measurement field is approx. 45 mm wide and 200 mm long. Ensure the pavement marking to
be measured is free of debris before taking measurements. Make sure that the instrument is
stable positioned.
Reason: The LTL-X has three support pads, each with a small footprint. An uneven marking
or a small piece of gravel trapped under one of the pads will move the measurement field and
affect the reading.
Taking the measurement
Press the green OK button to take a single reading. Do not put pressure on the handle when
taking a measurement.
Reason: Pressure on the handle can affect the measurement geometry and thus influence the
reading.
Number of measurements.
For accurate readings, do not take just one reading of a road marking. Three readings will
give a more accurate result than one reading. Five readings will give a more accurate result
than three readings, etc. Take the readings in adjacent areas of the marking. Let the instru-
ment calculate the average of the readings (fixed or moving average options).
Reason: A road markings retroreflectivity varies from area to area. It is not unusual to see
variations of 5% - 20% when the instrument is moved even less than 10 mm/ ½” in either di-
rection.
Obstructions in front of the LTL-X
Ensure the pavement marking to be measured is clear of any obstructions at least 1 meter/ 40
inches in front of the LTL-X. For example, do not stand in front of the instrument when tak-
ing the reading, and do not have anyone else standing in front of the instrument while taking
the reading.
Reason: The observation field of the LTL-X extends beyond the front opening of the instru-
ment.
RPM’s/retroreflective materials in front of the LTL-X
Recommended Procedure: Ensure there are no retroreflective materials not belonging to the
marking at least 1 meter / 40 inches in front of the LTL-X. For wet road markings this dis-
tance is 2 meters/ 80 inches. Examples of such materials are raised pavement markers, high
visibility clothing and shoes with retroreflective properties. Whenever the user suspects that
materials ahead affect the reading the material should be covered with a dark cloth.
Reason: The observation field of the LTL-X extends beyond the front opening of the instru-
ment, and such retroreflective materials can cause false readings.