How bumpy is the Czech D1 Highway, exactly?
Czech Radio data team measured the shocks your car receives when driving on the Czech bumpiest highway. Explore the meter-by-meter interactive map and find how shaky it gets at the most forgotten sections, and how the car glides at the newly refurbished ones.
This scheme of the D1 motorway shows the intensity of the measured vibrations. Red colour represents the most damaged sections of the road, green colour marks the sections of smooth and silent driving. On both sides, you can see the results of the measuring both from the front and the rear wheel. When you hover over the scheme with your mouse, a detailed view of the corresponding section in an aeronautical chart will pop up.
The first big bump on the journey from the Czech Radio building in Prague to its Brno branch occurs while we are still in the city, crossing the tramway track at the I. P. Pavlov square. Before drivers reach Brno, they must cross about eight hundred similar (or even worse) diagonal “tracks”, and eight hundred more on their way back.
The strongest individual bump we recorded was at Vysočina on our way to Brno on the 127th kilometre, between Velký Beranov and Měřín. The vibration lasted for 19 milliseconds and the momentary overload of the rear wheel reached 16 G, which is 16 times Earth’s gravity. (Vibrations inside the car are much weaker, however, as they are absorbed by the car’s suspension system and seat upholstery. Also, the human body is able to cope with a much higher overload, at least in a short term. For the measurement details see the “Measuring Method” box and for possible health issues see the chapter Dangerous. Harmful?) The largest pothole we encountered on our way back was on the 178th kilometre near the exit to Ostrovačice.
The longest continuous sections of the motorway with a bad surface are in the direction of Brno just before Větrný Jeníkov, between Jihlava and Velké Meziříčí and between Bíteš and Ostrovačice. On their way to Prague, cars and passengers will go through the worst bumps between the Devět křížů rest stop and Velká Bíteš, behind Větrný Jeníkov and between Šternov and Hvězdonice.
“Your measurement is identical to those carried out by the Road and Motorway Directorate,” says Ivan Čásenský, RMD’s Construction Site Manager. “Based on these measurements, we decide which sections will be repaired first. We started reconstructing the Měřín section and it should be finished by 2017. We are aware this is the worst segment of the motorway, and we need to fix it.”
The contract for the reconstruction of this 7 km long section was awarded to the Eurovia and STRABAG consortium. The price for the repair to be paid by the RMD is one billion Czech crowns.
The reconstruction: Can it be done in time?
This autumn will see the end of the third season of the monumental D1 refurbishment project with a planned budget of 24 billion. The RMD separated the motorway into 21 sections and announced an independent tender procedure for the reconstruction of each of them.
Three years later, only four sections have been finished, i.e. 35 kilometres out of the total of 161, which is why the Central Auto-Moto-Club has issued a warning, that at this rate, the repairs can hardly be done according to the schedule.
According to the original plan, the entire refurbishment project was supposed to be completed in six years, which means a half of it should be done by the end of this year. But the RMD has recently postponed the date of completion by one or two years, i.e. to 2020 or 2021.
The delays have been caused by unexpected complications at the sites, like when a freshly laid cement concrete surface was flushed down by torrential rain, as well as by legal disputes between the investor and the developer or unsuccessful tenderers.
The section with the worst delays is section No. 21 between Lhotka and Velká Bíteš. Here, after removing the original concrete layers, the constructors found the road bed to be in a worse condition than expected. For the extra work associated with its remediation, the OHL ŽS and Alpine Bau consortium asked for more money than the RMD was willing to pay. The situation got even worse after Alpine Bau, the parent company of one the suppliers, went bankrupt. The construction was ground to a halt for 200 days, and together with the winter break, its completion was delayed nearly by a year.
This year, construction works started at three sections, two more will follow this spring. RMD’s construction site manager Ivan Čásenský believes that despite the delays, the repairs will be finished by 2020. “We follow the schedule. The complications near Velká Bíteš are not stopping us.”
Dan Ťok, the Minister of Transport (the ANO movement), has been showing his effort to step up the pace of the construction works in the media. His most prominent contribution was when he requested to continue work during the night. According to Ivan Čásenský, who has been monitoring the quality and pace of the repairs on the sites, no Minister can influence the proportion of work that can be done during the night, which is about 15-20 %.
“The works that were supposed to be performed during the night within the first stage (i.e. before Mr Ťok was appointed as the Minister – ed. note), will be performed in the second stage as well,” says Čásenský. This applies e.g. to the removal of old flyovers and erection of new ones, which usually requires a complete – however short – road closure, and that can only be done at night.
Our test drive confirmed that even on weekends, the works on the sections under repair continue at full speed.
Measuring the Highway
We chose Sunday for the drive to Brno and back to avoid the lorries and the worst traffic jams in our measurements of vibrations. To make the measuring as precise as possible, we stayed in the right lane during the whole journey – if possible – and kept the speed at around 100 kph.
For the testing car, we chose a 2-year-old Volkswagen with a multi-link rear suspension and tires inflated according to the regulations. We attached two accelerometers to the non-padded parts of the suspension close to both rear wheels. You probably have these electronic components inside your smartphone, allowing it to “know” when, in what direction and with what force are you moving it and to use it e.g. as a pedometer.
These sensors were measuring the momentary overload thousand times per second and transferring it wirelessly to the computer in the driver’s cabin, where the data were synchronised with the GPS co-ordinates. The sensor attached to the side glass with an adhesive tape recorded the car’s position ten times per second. Driving at 100 kph, we were able to localise every vibration with a precision of a few metres. For further technical details and the complete retrieved data see our Github.
Pieces that don’t fit
While momentary overload of the rear suspension may be an exact physical quantity, it does not tell us much about the comfort and safety of driving on the motorway. The human body can absorb a much higher overload then the 16 G we measured, if it lasts only a few milliseconds: for example, if you jump in the air and fall back on your heels or if someone slaps you really hard, the momentary overload may reach up to a hundred times Earth’s gravity. Furthermore, the passengers are protected from the bumps by tires, shock absorbers, bodywork, and seat upholstery. That is why we asked professional drivers about their personal experience.
Karel Horák has been a bus driver for more than forty years. Three times a day he sets off to the Prague – Brno route on the D1 motorway. “The motorway is bumpy, damaged. It has been like this for at least ten years. It ruins the vehicles and us drivers, too,” said he in a Czech Radio interview.
He discourages everyone from driving in the right lane the whole time, like we did. In the worst section of the motorway, for the sake of the passengers’ comfort and the service life of the vehicles, he drives in the left lane, despite having been fined a couple times by the police.
Spilled coffee in the passengers’ hands is the least the potholes can do to the bus. “Everything is shaking. The steering wheel is vibrating. In the worst stretches, there’s nearly dust coming from the rugs.” It’s my third bus on this route and every time I get a new one, after a week the whole thing is rattling, bouncing and squeaking again,” describes the driver his everyday anguish on the bumpy motorway.
Twice he broke the torsion bar, a 5 cm thick prop that prevents the front part of bodywork from collapsing, while driving on the D1 motorway. “I thought this could only happen in rough terrain.”
The D1’s bad reputation exceeds the borders of the Czech Republic. Dima Stoianov, a Moldavian journalist who took his wife on a trip from Kishinev to Prague in the summer, confirms this: In a telephone interview for Czech Radio, he said: “We drove more than three thousand kilometres on Moldavian, Romanian, Hungarian, Slovak, and Czech motorways. We encountered only two really bad patches: near Kishinev, but this is the standard here, and then between Brno and Prague. We were surprised because we thought that the further west we’d go, the better the roads would get. As it turned out, they could get worse.”
“We drove a good car, but this old, Soviet-type motorway made out of poorly connected concrete slabs made it jump up and down. It was really bad and it went on for more than hundred kilometres. It only got better right before Prague,” recalls the Moldavian journalist. He says the D1 motorway is like “a jigsaw puzzle made of pieces that don’t fit”, where “high speed is your enemy”.
Dangerous. Harmful?
Driving on a damaged motorway is not only uncomfortable, it can also be dangerous: “The contact between the tires and the road is decreasing, and so are the dynamic forces that the tire can transfer onto the road. These forces are both linear and lateral, the former comprising the retarding and driving force and the latter being necessary to change the driving direction. This means the braking distance is extended and the car’s controllability and stability worsens,” explains David Haidinger from Škoda Auto the opinion of its technical development experts.
“Sudden one-sided bumps transfer the vibrations into steering and it is necessary to constantly correct the driving direction. Ruts significantly influence the directional stability and change the expected behaviour of cars. Large potholes may damage the rims and lead to an air leak or a substantial wheel and tire damage. All of this can lead to dangerous situations,” he adds.
The risk of accident increases in cars with worn shock absorbers. Under ideal conditions, absorbers can last up to 200 thousand kilometres, but damaged roads substantially decrease this number. That is why Škoda and other car companies recommend to have the car checked every 60 thousand kilometres.
According to David Haidinger, it is difficult to say exactly how much driving on uneven surface decreases the service life of the absorbers and the whole car. “This depends not only on the condition of the road, but also on the driving style, the total load weight of the vehicle, tire pressure, and many other factors.”
Until the drivers are in a car crash, damaged roads do not seem to be harmful to drivers and passengers. If we examine the occupational disease statistics to which excessive vibrations may contribute, each year there are 200 new cases caused by working with tools such as jackhammers, drillers or angle grinders, but almost no diseases of professional drivers.
This is also caused by the fact that in the Czech Republic, unlike in other countries, damage to lumbar vertebrae, the part of the spine that is most affected by vibrations, is not acknowledged as an occupational disease.
“No, not even frequent driving on a damaged motorway can damage your health,” says Zdeněk Jandák, the head of the National Reference Laboratory for Measurement and Evaluation of Noise and Vibration in the Work Environment.
As in the case of electric tools, the laboratory assesses the harmfulness of vibrations transferred from car controls onto the driver’s hands and also the overall level of vibrations transferred from the seats, pedals, and floor onto the human body. There are health limit values for both types of vibrations. But no measuring has shown so far that driving on a motorway with uneven surface would lead to exceeding these values.
“It cannot be excluded. The motorway is in such a bad condition that not even the suspension of executive cars can absorb the bumps. It is possible that if we had placed the sensors directly on the seat, the exposure limit values would have been exceeded there. But these values apply to regular exposure. This means that the driver would have to spend most of his shifts on the most damaged sections and drive at a higher speed,” says the noise and vibrations expert Zdeněk Jandák.
According to him, health problems may also occur if the driver holds the steering wheel too tightly: “When similar complications occurred in the past, they were always caused by the drivers clenching the steering wheel with excessive force. When we measured the vibrations on their steering wheels, they never exceeded the limit values.”This means that the complications were caused by their tight grip, not by the vibrations. A person holding a steering wheel – or anything else – too tightly for too long, is threatened by vasoneurosis, a blood vessels disorder in hands.
Why so bumpy?
As our visualisation shows, even the newly repaired sections of the motorway are not perfectly smooth. According to Ivan Čásenský, RMD’s Construction Site Manager, this is not a fault, but an intention. The chosen method of reconstruction, i.e. using rough cement concrete for the motorway surface, does not provide as much driving comfort as smooth asphalt would. Nevertheless, cement concrete will last thirty to forty years, five times the 8-year service life of asphalt.
“The costs and noise levels are a little higher, but the service life is much longer, which means lower repair costs in the long term and safer driving. Especially in the winter and in bad weather conditions like those at Vysočina,” Čásenský explains. According to him, the refurbished motorway undergoes detailed testing including noise measuring and he adds: “on the scale from 1 to 5, 98 % of the sections score 1”, which is the best result.
Despite that, the RMD still opts for asphalt in certain cases. They use it in the more densely populated areas in the vicinity of Prague and Brno, because it makes driving more silent. Asphalt concrete is also more flexible than cement, which is why it has been used on bridges, as they tend to shrink or expand when subjected to changes in temperature. That is also why the bridges were rated as one the best sections in our measuring.
The D1 plans were drafted during the first Czechoslovak Republic (1918–1938) and the construction of the first tens of kilometres commenced during World War II. But the bigger part of today’s motorway, including the infamous concrete slabs with faulty drainage system and constantly expanding joints, comes from the 1970’s.
According to Mr Čásenský, who is a civil engineer, there is no major fault in the design itself or in its implementation. The workers simply used the technology and materials available at that time, and after forty years and only minor repairs, the service life of the motorway simply expired.
“When you start deconstructing a house that was built forty years ago, you always find things you won’t like and that were done sloppily,” he adds. “But it can’t be said that we found any obvious construction faults. It is the bad drainage system that presents the major problem for the service life of the motorway.”
The RMD therefore opted for a rather radical method of reconstruction, where the motorway will first be widened so that a whole lane could be closed, after which the workers will remove the damaged surface, reinforce the road bed and then lay a new concrete layer upon it. They will also replace the flyovers. This is because of the faulty drainage system, which is the reason why the joints between the concrete slabs are soaked with water that expands them even further, that the key component of the repairs is the reconstruction of the central reservation (or “median strip” in American English). Beneath it, there is wiring and a sewer system that often gets filled up or breaks and does not serve its purpose.
If the service life of the arterial motorway expired ten or fifteen years ago, why weren’t the repairs commenced earlier? The answer is a familiar one: There was not enough money (the refurbishment costs are paid by the EU, State Transport Infrastructure Fund, and the Ministry of Transport) and “political will”.
“Preparation of a contract of this proportions does not take a year, but five or six years of hard work, designing probing, road diagnostics, searching for the best repair technology. It took three more years to obtain the necessary money. That is the span of two different governments. The Ministers of Transport came and went, and everyone had different priorities.
Once upon a time near Ostředek
The sensitivity of the sensors we used for measuring the vibrations is apparent from the aerial photograph of the motorway bridge between Ostředek and Český Šternberk. When you click on the image, you will see that the accelerometers on both wheels react even when crossing the joints between the concrete slabs: the thicker the red colour, the stronger the vibration.
Chystáte se o víkendu na D1? My jsme ji nedávno projeli s vlastnoručně vyrobeným senzorem otřesů. Na obrázku je vidět,...
Posted by DataRozhlas on 16. říjen 2015
After Czech Radio posted this image on Facebook, there was a comment added, among others, by Petr Pištěk, a civil engineer who participated in the repairs of the depicted motorway bridge more than twenty years ago. As a site engineer of one of the subcontractors, he was in charge of a team of workers that removed remnants of old concrete from structural frames with a high-pressure water jet. The main contractor for the construction project was ŽS Brno.
“It was a general overhaul. Load-bearing pre-stressed beams made of reinforced concrete were the only things left from the original bridge. The complete structure above them, that is the levelling layers, waterproofing, wearing layer, all of that had to be done anew,” described Petr Pištěk the extent of works in an interview for Czech Radio. The 1993 reconstruction was therefore probably just as radical as the current one.
The thing that surprised the rookie civil engineer the most after arriving at the construction site in 1993, were the other civil engineers’ extraordinary relationship with the motorway patrol. The success of the construction depended on how fast the policemen approved the necessary traffic restrictions.
“The main contractor’s CEO arrived for the inspection day and gave the policemen keys to a new car right off the bat,” recalls the civil engineer that the good relationships were being improved, among others, with sponsorship donations. “It had a side effect, too: In case the police ever caught us in the Mirošovice section committing an infraction, we were instructed to say the name of their chief and add the shortcut ‘ŽS’ to it. This was supposed to be some kind of magic formula to let us leave without a fine,” says Petr Pištěk.
As is the case of any large construction, unexpected complications occurred during the reconstruction of the bridge near Ostředek. According to the original plan, the grade course of the bridge was supposed to be modified. During the construction, it turned out this would not be so easy. The project had to change in the nick of time. “The next inspection day was intense. We had to find a way to ‘fracture’ the bridge so that the passage would be smooth. RMD had to come to terms with a compromise,” recalls the civil engineer. But according to him, this compromise is functional and even after the years, it does not diminish the comfort of driving on the bridge.
As Petr Pištěk recalls, another problem occurred just before the completion of the construction, this time because of the waterproofing. It was supposed to sustain even high temperatures during the process of laying the final asphalt layer. But when the first truck started laying the hot asphalt, the waterproofing melted under it and the contractor had to replace it on one half of the whole bridge. As the autumn deadlines were approaching, the construction site had to be conserved and the reconstruction was delayed by several months. The cost of repairs and the high penalty for delay were debited to the supplier of construction chemicals, who in the end probably suffered a loss because of the faulty waterproofing supply.
“According to the original plans, this construction project was supposed to benefit primarily the suppliers of construction chemicals. There was not much of a competition at that time. As small town guy I was staring at their prices and the excessive numbers of planned metres and I couldn’t believe my eyes. These were amounts I couldn’t even imagine. Only later we found out that the contractor was purchasing the construction materials from a different company, putting on a different label and adding margins in tens of percent.”
According to Petr Pištěk, the atmosphere at the site was often tense. Not only big money, but jobs were on the line, too: “The first half of the 1990’s were uncertain times. Especially at the RMD there were too many people and all of them had to defend their positions. They were running around the construction site, looking for sources of possible problems to focus on.”
Mr. Pištěk does not want to comment on the current reconstruction of the D1, as he is not familiar with the business terms nor with the technology used. But he does think that the repairs seem to be “taking a suspicious amount of time”. He says the D1 is “cursed”. “The only solution would be to tear it down and build a new one somewhere else,” he proposes laughing. “No one can save it now, not even if they extracted it to its very footing bottom.”
