Easy and Accurate: Grade and Slope Control with 2 Big MultiPlex Skis
SUPER 1900-2 builds rural road without tensioned wires
How to build a road true to line and level without an existing reference ? The Big MultiPlex Ski, VÖGELE’s sensor system for grade and slope control, was fitted to a SUPER 1900-2 and helped German contractor Leonhard Weiss achieve a perfect paving result when rehabilitating a rural road in the Swabian Alb region in Germany.
On account of road damage and an increase in traffic volume, a 2km stretch of the L438 rural road between Böttingen and Dürbheim in Baden-Wurttemberg needed rehabilitating and widening.
Placing the base course had already begun last year. The roadworks, however, could not be brought to a close due to bad weather and the pavement, though not completed, was opened to traffic for the winter. In the spring of the following year, the base was in a poor condition as expected, spread with cracks, rutting and potholes. The Regional Authorities of Freiburg, letting the road rehabilitation contract, saw no other choice than to mill off parts of the base course and start from scratch. The Regional Authority preferred working with tensioned wires, as no reference such as kerbstones or the like existed along the roadway.
But thanks to an alternative, there was no need to carry out time-consuming surveying and preparation of the job site as would have been necessary for grade and slope control with tensioned wires. The paving team of contractor Leonhard Weiss moved onto the job site with their SUPER 1900-2 fitted with two Big Multiplex Skis. They carried out grade and slope control without a reference. During paving, the result was constantly monitored and checked by the Regional Authorities of Freiburg. According to the specification, the tolerance admitted for evenness in the longitudinal direction was 4mm over a distance of 4 metres. Thanks to NIVELTRONIC Plus®, the System for Automated Grade and Slope Control installed in SUPER pavers, the finished pavement fully complied with the specified requirements.
Paving without tensioned wires saves costs
The successful outcome of the project proved that contractor Leonhard Weiss’ decision was right: working with two Big MultiPlex Skis instead of tensioned wires was the clue. All so more so with regard to pave width. For working with a tensioned wire installed on one side only, the recommended pave width is confined to 6.5m. Otherwise, the specified evenness on the side controlled with the slope sensor cannot be guaranteed. On this contract, however, the width of the carriageway varied between 6.5m and 8m.
Furthermore, the L438 is a winding road featuring a varying crossfall. On jobs like this it is almost impossible to achieve a perfect surface accuracy with just one reference wire. When considering the material and time required for surveying and installing two wires, considerable costs incur. Based on an estimated expense of some 1,750 Euros per linear metre of tensioned wire, an extra charge of some 7,000 Euros would have accrued for this job site.
SUPER 1900-2: Facts and Figures
- Maximum pave width 11m
- Laydown rate up to 900 tonnes/h
- Maximum layer thickness 30cm
- Transport width 2.55m
- Pave speed up to 25m/min.
- Travel speed up to 4.5km/h
- PERKINS engine rated at 142kW
- ErgoPlus® operating concept
Mounts and operates very easily
Mounting the Big MultiPlex Skis is simplicity itself. With the beam made up of several 2-metre elements, the system can be fitted quickly by just one person. Attaching the Big MultiPlex Ski to the screed arm offered a great advantage over attachment to the screed’s end plate. In this position, the sensors scanned the base and level-regulating layer within the screed’s pave width and not the strip of crushed stone at the roadside. This gradually improved the evenness from layer to layer. On the job site in Baden-Wurttemberg, the Big MultiPlex Skis covered a distance of 11 metres each. Thanks to the pivoted brackets, the Big MultiPlex Ski can be swung outwards within the range of one metre. The individual sensors are displaceable on the beam for optimal adjustment to job site conditions.
VÖGELE developed the Big MultiPlex Ski also with its practical handling in mind. The Big MultiPlex Ski comes with a simple design and its operation is easy. Control of the Ski is from the ErgoPlus® screed console into which NIVELTRONIC® Plus, the VÖGELE System for Automated Grade and Slope Control, is fully integrated. The team from Leonhard Weiss was enthusiastic about the combination of their SUPER 1900-2 and the Big MultiPlex Skis. “Paving is child’s play thanks to the user-friendly ErgoPlus® operating concept,” said foreman Reinhold Schopf, and he adds: “We were much impressed not only by the machine’s comfortable operation, but also by the outstanding paving results.“
The Big MultiPlex Ski levels out irregularities
The Big MultiPlex Ski is suited for the most varied applications. The system is ideal for jobs on which long irregularities in the base need to be levelled out. This is achieved by 3 sonic grade sensors and a mean value calculated from their measurements. A single sensor would not be capable of detecting a long irregularity as a fault. And this was exactly the feature required on the job site in Baden-Wurttemberg. Especially when paving binder course it was necessary to level out any remaining irregularities in the previously placed base and level-regulating layers, in order to achieve a surface course of absolute evenness, true to line and level.
Feel the evenness
The SUPER 1900-2 was combined with an AB 500-2 TV Extending Screed equipped with tamper and vibrators that provided for excellent pre-compaction. The achieved evenness was superb. “I could even feel it from my seat,” said Sahim Yldirim, a roller operator from Leonhard Weiss’ team.
Highlights of the Big MultiPlex Ski, the sensor system for grade and slope control
- Comprises 3 sonic grade sensors provided with 5 sensing cells each. Sensors are attached to a telescopic beam.
- Out of the sensing cells’ 5 measurements, an average is calculated from the 3 best ones. This serves to filter out large obstacles and minor irregularities.
- Non-contacting operation. Sensors can be set to a variable height between 200 and 650mm.
- Ideally suited for levelling out long irregularities in the base.
- Ski length variable between 6.5 and 13.5m.
- Suited for the most varied applications, also on curved sections.
- Easy operation. Mounts easily and quickly to either the screed arm or the screed’s end plate.
Job Site Details
Rehabilitation of the L438 rural road between Böttingen and Dürbheim in Baden-Wurttemberg, Germany
Length of section: 2km
Pave width: 6.5m – 8m
Layer thickness: Base course: 12cm
Binder course: 6cm
Wearing course: 4cm
Base course: Asphalt base (0/32 CS)
Binder course: Asphalt binder (0/16)
Wearing course: Asphaltic concrete (0/11)
Crushed-stone base: 16,000t
Asphalt base course: 4,100t
Asphalt binder course: 2,050t
Asphalt wearing course: 1,400t
SUPER 1900-2 with AB 500-2 TV Extending Screed and 2 Big MultiPlex Skis