End of construction, beginning of maintenance. With the completion of the modernization of the oldest and busiest Czech roads, the question arises of what the new roof will withstand and what care it will need. However, the highway’s new surface is under more scrutiny than it might seem.
The observation car, which maps the entire highway, reveals not only visible damage at first glance, but also small cracks that can only be seen with the eye if someone is walking on the highway on foot. And of course not.
Good news to begin with: The first measurements of the sections that have already been completed show that the highway is technically well built. “We just learned about it. Basically, a completely new highway was built here in operation. In any case, in terms of flatness, anti-skid properties and deviation from geometry, the new D1 is in top-notch condition,” he sums up to iDNES.cz Results of the first measurements in some recent divisions Tomáš Miniberger, CEO of VARS and Highways. The first inspection of the motorway is completed immediately upon completion – this record is then used by ŘSD as an argument in the complaint.
When drivers notice, it’s too late
The “spy” takes the form of an orange truck, which is equipped with high-resolution, high-resolution scanners that use laser technology to monitor the surface of the highway. They can handle it even in poor lighting conditions and most importantly: they can handle it at normal speeds. The observation car, known as the CleveRA Car, travels more than eighty kilometers per hour, so it connects no more than an ordinary truck.
“Broken edges of expansion joints are now discussed in the media, but microcracks are a much bigger problem. If not caught in time, they will turn into cracks after eight to twelve years, which is a serious failure for this type of cement-concrete road. Then it is necessary to replace the entire board between the expansion joints”, explains Miniberger.
Experts who evaluate scanner shots distinguish four stages of concrete surface failure – from undamaged to minor and severe damage to severe cracks that require a complete reconstruction of the partition. True, before the last stage, the average motorist in the car does not know about any problems. Only at the last stage do pieces of concrete begin to crumble from the surface of the highway and – in technical terms – there is a loss of mass. But it is too late to make partial repairs.
However, the scanners in the surveillance vehicle are so accurate that they detect even irregularities smaller than a millimeter. “The most important thing is to monitor the surface regularly. Thanks to this, the investor – in this case ŘSD – has an overview of the current situation, but also of how the surface is gradually deteriorating. This is a strong argument for him in a potential complaint, and at the same time allows potential problems to stand timely and perform scheduled maintenance or repair as efficiently as possible,” Miniberger explains, adding that regular maintenance and ongoing repairs are always substantial cheaper than major repairs in the long run.
On the D1 motorway, VARS will regularly monitor, in addition to the small cracks, the condition of those “media-attractive” edges as well as the asphalt grout that fills the expansion joints. The car travels the entire highway every year, and so far such monitoring is scheduled for 2024.
Broken edges? Pan-European Concrete Trend
A few weeks ago, there were reports that new sections of the highway had “broken” edges from expansion joints. According to Miniberger, these defects are much less dangerous than microcracks. It is likely caused by the fact that the joints were cut before the concrete hardened properly. “Like microcracks, it is the result of compaction for the shortest possible construction time. In general, cement is now used all over Europe, is stiffer and has greater strength, but simply degrades more than the road cement that has been in use for decades.
And moderate and heated discussions about whether it is right to update the D1 with a concrete-cement surface instead of asphalt concrete. “Structurally, there are completely different approaches. They have other flaws and they are fixed in another way.” Asphalt concrete is cheaper, cheaper, and easier to repair – for example, by grinding the asphalt and laying new carpet – but it generally lasts less. “The concrete and concrete highway has a planned life of 30 years, but the idea that it shouldn’t be touched all the time has long since been lost,” Miniberger concludes.