Paving Principles and Control Methods
P-32+ and P-32 Operator’s Manual P/ N: 1001547-01
Non-stop, continuous operation of paver
Constant speed of paver
Tr u ck exch ang e
Head of material
– Mix Temperature
Quality of Base Being Paved
The following sections describe the three types of control possible with your Topcon P-32+ or P-32 System:
sonic, laser, and slope.
You can choose either Topcon’s ST-3 (P-32+ System) or the Sonic Tracker II (P-32 System) as a sonic control
elevation reference for your system.
The Trackers measure and control the elevation of the screed, controlling grade from a physical grade reference,
such as a curb, stringline, or existing road surface. For both the ST-3 and Sonic Tracker I I, a transducer, located
in the Tracker, generates a number of sound pulses per second and listens for returned echoes like a
microphone. As soon as the Tracker sends out a sound wave, it starts a stop watch.
The sound waves go down, bounce off of a physical reference, and reflects back to the Tracker. The Tracker
measures the time it takes for the sound wave to return to the Tracker. Knowing the speed of sound, the Tracker
accurately calculates the exact distance to the grade reference (Figure 25).
The ST-3 is Topcon’s new generation Sonic Tracker. The ST-3 was designed after years of experience with non-
contacting sonic grade controls in the construction industry.
The ST-3 has two detection modes to ensure the best accuracy possible as well as changing sensor
characteristics to optimize the detection zone based on the application. The two modes are Surface Mode and
Stringline Mode. Surface Mode is used to detect the ground or curb. While in Surface Mode, the grade indicators
display the traditional up/ down and ongrade arrows. Stringline Mode is used to detect an elevated stringline.
Changes in any of these factors cause a change in mat thickness, density, surface appearance and
mat quality. I f changes must be made, make them as gradually as possible. Abrupt changes in any of
the above factors produce rapid changes in mat thickness, adversely affecting mat quality.