COSON-ST: “CPT with just a single push on the button!”
COSON-ST: “CPT with just a single push on the button!”
The VLG, the Department for Field measurements and Laboratory works within the City of Rotterdam, has been using the new Track-Truck with the cutting-edge COSON-ST for hands-free CPT for a few months now. We are curious about the first field experiences and therefore dedicate our frequently recurring feature "Partners in Geotechnical Services" to this customer. We spoke with the CPT operators Mark Kuiper and Harry Verhagen. Mark has been working as an operator at the VLG for 12 years. He works together with Harry, who has basically spent his whole working life as an operator for the VLG. Combined they have operated many different CPT systems and worked with various cone types and their careers are now at a pinnacle with the hands-free COSON-ST. It is unquestioned that they know what they are talking about.
Did you already use the COSON-ST often?
“Sure, with the COSON-ST we executed approximately 260 CPTs in Amsterdam and a project in Rozenburg with 32 CPTs and 30 magneto measurements. Remaining days are filled with two to eight CPTs at various locations, for example in the city of Rotterdam.”
How do you like working with the COSON-ST?
“We are very satisfied with this modern machine! Compared with standard CPT systems we are particularly enthusiastic about the enormous reduction of physical strain and the timesaving in a CPT cycle. At one project location we can achieve an average production of 10 CPTs of 40 m. On days with favourable conditions and if we work a bit longer, we have even reached 17 of these CPTs."
Can you explain this in some more detail?
“The causes for physical strain have been removed. After all, you do not have to lift, guide and screw CPT rods anymore. The temporary up-and-down moving of the CPT string, to reduce the total friction around the string in case of heavy CPTs, is also much easier due to the automatic assembly and disassembly of the CPT string."
“Looking at timesaving, these are already noticed during the preparations. There is no need to raise a hatch and to place an end set including inner casing. You just have to stick the Icone underneath. The timesaving in the CPT cycle is mainly achieved during pulling.”
Already during testing it was proven that a complete 50 m CPT can be performed approximately ten minutes faster with the COSON-ST with two hydraulic clamps than with the HYSON with one clamp. “Furthermore, after one push on the button, our hands are free to prepare the next test. One of us monitors the CPT process and the other can go outside to the next test point to remove paving and/or and pre-drill. We can rest assured that the system will do the physical CPT work by itself."
Can you mention other strengths of the system?
“The application of thicker CPT rods, 40 mm instead of 36 mm, is also a big advantage. We have regularly pushed with a force of more than 15 tons without any problems, whereas with previous CPT systems we were already on guard with respect to breakage at lower pushing forces. With these thicker rods the risk of buckling and breaking is much smaller and that provides us with a lot of confidence. Due to these rods the time-consuming use of casing for lateral support is also required less often.”
“We have had a lot of experience with the previous “CPT-robot” from A.P. van den Berg in which the wireless Optocone system was integrated. This was already a very comfortable system to operate, but you still had to keep good track of a timely replacement of batteries. However, the ST-rods in the foldable string are fitted with a cable, so that point of concern has now disappeared.
This is not the only advantage of the cabled system. Because the cabled system has no momentary interruptions in data transmission, we are performing our magneto measurements with the automated system (COSON-ST) again.”
We can underline this advantage of the cabled system, but it stretches even further. Due to the larger bandwidth compared to wireless data transmission, all Icone click-on modules can be used to measure extra parameters. So also the Icone modules for seismic and for vane measurements.
“The self-seeking bayonet thread in the ST-rods also works really well. We were used to fasten the rods in three to four screw rotations, but with this ST-system we had to trust that the rods were properly tightened with just one short single twist. At first you are continuously paying attention. In the meantime the Single Twist (ST) has more than proven itself and feel very confident to let the system do its work.”
Are you satisfied with the introduction, implementation and service?
"Yes. In the beginning we had to get used to the modern system, so in the initial phase it was good to have an employee of A.P. van den Berg present for support at all time. From the moment we started working independently with the system, these employees have still been on stand-by.
It only happened a few times, but the questions that came up were addressed very fast and in most cases any necessary adjustments could be implemented from the computers in Heerenveen. In cases that a trip to us in Rotterdam would be required, we know their engineers will not hesitate and will show-up.”
Can you say something about future projects for the COSON-ST?
“At the moment we primarily make days with a small numbers of CPTs at various industrial locations. We can deploy the machine almost on a daily base. We do have a larger project coming up consisting of 35 CPTs at a single location in Amsterdam. It has already become apparent that the COSON-ST fits well with larger projects, because higher production rates can and should be achieved. Naturally, in these cases the gains in ergonomics (physical strain) and timesaving will carry more weight. But also for the smaller projects at different locations the machine remains to be well-suited, because the Track-Truck simplifies the mobilisation by road (on wheels) and the manoeuvring in soft or hilly terrain (on tracks).”
In summary the VLG emphasizes the benefits of the COSON-ST as the nearly complete absence of physical strain, the faster CPT cycle, the abundant time to spend on other activities and the grown confidence towards heavier and deeper pushes. This feedback makes us even more proud than we already were! Our innovative efforts are rewarded when they are recognized in the market. The best recognition is of course when a customer decides to purchase the COSON-ST and then shows pleasure and satisfaction while operating the system. The VLG is the first ST-practitioner, who will follow? The COSON-ST can be built into a Track Truck, a CPT Truck and a CPT Crawler. Still not convinced? View a video, the leaflet and/or contact us here.