LONGITUDINAL PROFILE CALIBRATION DEVICE
The ROMDAS (Road Measurement Data Acquisition System) is a low-cost system designed to collect road and pavement data using any vehicle. ROMDAS can be used for the following surveys:
Roughness using response-type roughness meter
Pavement condition rating
Transverse profile and rut depth
Heading and cross-fall
Travel time and congestion
Video logging of right-of-way and pavements
This specification note describes the ROMDAS Longitudinal Profile Calibration Device ((LPCD)), an instrument developed to accurately measure the road profile.
The ROMDAS LPCD consists of:
- a three wheel cartthree trigger platescalibration shims
carrying case data acquisition andsoftware analysis
The LPCD is used to measure the road profile. It qualifies as a Class 1 calibration instrument based on WorldBank Technical Paper 46.
Figure 1 shows the LPCD performing a survey.
Figure 1: LPCD in Use
The LPCD is operated by first establishing the wheel path be measured. Trigger plates are placed at the startand the end of the test section. The third trigger plate is placed at a distance of 10 m from the start. This is used to correct the distance measurements for temperature effects.
The operator starts the LPCD data logging software on a notebook PC or Palmtop computer (not supplied) whichis connected to the LPCD via the serial cable.
The LPCD is pushed along the road so that it passes over the first trigger point. This starts the measurements. At a distance of 0.3 m the operator stops the LPCD and an elevation reading is automatically taken. Theoperator then continues to 0.6 m, stops, and another reading is taken. This is continued until the full test sectionis measured.
An LCD display shows the chainage and LEDs are used to assist the operator in stopping ever 0.3 m.
Software is supplied to process the LPCD data into the elevation profile of the road (in mm). The profile can thenbe analysed to calculate the international Roughness Index ((IRI)) in m/km.