Unitsky String Technologies
17 July 2016
How SkyWay has solved the problem of noise emission
The information service of the SkyWay Group of Companies has prepared for you a unique footage of tests on truss-string elements of the SkyWay overpass for acoustics and vibration with the aim to prove the advantages of structures filled with special SkyWay concrete over hollow structures.
Comparative analysis took place in the Laboratory of construction acoustics and vibrational safety at the Belarusian Scientific Research Institute on Construction (BelSRI) already familiar to our audience. The Chief designer of the Department on infrastructure, tooling and test equipment of Skyway Technologies Co. Yury Kashchuk will talk about the purpose and the tests in more detail.
At the end of the video, the General Director - General designer Anatoly Yunitskiy will speak about the nature of such phenomenon as noise in transportation, its effects on city people, and also about how they solved the problem of noise emission in the SkyWay transport system.
Translation of the video:
Minsk Dzerzhinskogo Ave one of the radial city highways directed to the city of Brest
Good day! Here is Mikhail Kirichenko. You are watching SkyWay news, where we tell you about the developments and implementation of breakthrough transport technologies.
Sorry for this noise. We are in the city center. The Earth's population is constantly growing. The noise pollution level in such place exceeds 90 decibel and has a tendency of increasing by 0.5 dB every year. Noise level rise is the main problem for the environment in such precincts. According to medical research, it results in increased neuropsychological diseases, high blood pressure, etc. In addition, housing density does not allow using such methods of noise damping as highway widening, planting trees or erection of noise protective barriers. Therefore, the most prospective and radical means of noise control is noise reduction of vehicles themselves. Yunitskiy's rail-string technology is developed also for reaching this objective. Our today's report is just about the tests of SkyWay track structure directed at noise suppression.
But first, a little theory. High-speed railways are built in many countries around the world. Most of them are designed with individual features that are determined by the type of operating trains, track width, electrification system, etc. The dominant noise sources for trains, moving at speeds up to 250 km/h, depending on the specifications of the train, are the system "wheel - rail" (rolling noise) and the engine system, characterizing its power and the generated traction force of a train, as well as various auxiliary systems (for example, air conditioning for coaches). With increasing speed, aerodynamic features become increasingly important as a source of noise. As we have already repeatedly touched upon multiple superiority of the SkyWay rolling stock over all the competitors in this component, today we will focus on the main source of noise emission.
As a result of interaction in the "wheel - rail" system on high-speed trains, there occur guiding structural vibrations, and the vibrations of a vehicle fall into the category of mechanical noise sources. These sources usually dominate the total noise level at intermediate speeds, and cover a very wide speed range. The noise of the "wheel - rail" system is caused by the roughness elements on the working surfaces. The spectrum of this noise reaches peak values at frequencies from 2 kHz to 4 kHz, and with increasing speed, it is growing faster than even the engine noise. The noise gain from the trains is closely linked to the speed increase. For example, the speed increase twofold causes the rise in acoustic pressure level by 18 dB (to the sixth power in proportion to speed increase). In Japan, where there is the greatest experience in arranging high-speed traffic, the process of its development was followed by in-depth scientific research, including the one in the area of noise, which began in the process of building a high-speed line Tokaido.
Initially they mainly studied the noise inside the coach. However, after a few years, increased attention to the problem of noise pollution of the environment along Shinkansen lines required the installation of noise barriers in high priority areas. Since then, the fight against noise pollution of the environment in this network belongs to the most important ones.
On the example of the Shinkansen train, they produced diagrams of noise sources dominance during the time of train passing along the point at which measurements were conducted. The share of each of the noise sources in the noise pollution of the environment in Shinkansen right-of-way lines has changed over time.
From the start of high-speed lines operation, the rolling noise dominated. Later it has been reduced through the installation of noise barriers and removal of unevenness on rolling surfaces by the use of composite brake blocks, and subsequently by grinding the rails. In subsequent years, large progress has been made in smoothing the outer surfaces on Shinkansen network trains in order to reduce noise level and avoid snow buildup.
As a result of these improvements, aerodynamic drag was significantly reduced. Nevertheless, it is the noise from the "wheel - rail" pair that remains dominant, as here progress was less considerable. The errors of Japanese pioneers were considered in our project, and the SkyWay team is doing everything possible to ensure that its SkyWay transport would have the lowest noise level.
Laboratory of construction acoustics and vibrational safety at
Today we have a current ride to the fields, so to say. Well, Alexander, please introduce yourself and tell us about your lab.
Good day. I am Alexander Yakimchuk. I am heading the Laboratory of construction acoustics and vibrational safety at BelSRI. Our lab measures noise levels and sound insulation of structures: floors, ceiling panels, etc. We measure vibration levels, sound insulating protection of outer shells and conduct other tests on acoustics and vibration.
Thank you. Let us talk to Yury Kashchuk who will tell us what particular things were tested here from SkyWay technology and what it means for our project. Hallo, Yury.
Hallo. We have tested elements of the truss-string track. We made a comparative analysis of hollow structures and structures filled with concrete. Accordingly, we shall determine and prove the advantages we spoke about earlier. That is, concrete filling allows us, among other things, excluding such a negative component as vibration. Elements of the truss-string track were tested to prove advantages of concrete filling over hollow structures. Thanks to Alexander we have conducted such comparative analysis in the lab. Tests for vibration and sound effects were carried out both on a hollow sample and the one filled with our concrete.
Territory of "Belenergostroy" plant (branch of "Belenergostroyindustria")
This is the sound of steel. Now the rail is filled with concrete. And this will be the sound of SkyWay. As they say, feel the difference.
SkyWay Technologies Co.
Noise in a city becomes the leading factor by its harmful effect on man. It has even more negative impact on man compared with gas-polluted air, with smog. This problem is actual in many countries, not only in cities, but also in countries, especially in high-speed transport. I am going to give you some examples how they fought with noise in Japan. When they started to build first high-speed railroads Shinkansen and steel bridges, viaducts, a serious problem arose because people living close to these roads and steel bridges started to write letters to the Government requesting to remove the roads. To dismantle the roads as it was not possible to live nearby because of the high noise. The Japanese tried to solve the problem in any possible way. They covered steel structures with polyurethane, rubber. They failed to remove noise. They found a simple solution - they prohibited legislatively construction of steel bridges and viaducts. The basis for our overpass is steel. If we make it simply of steel, the problem of noise will not disappear. We would not solve it. Therefore, I passed over to steel reinforced concrete structures, because concrete has one peculiarity. It consists of mineral particles of various size. Due to the forces of internal friction, oscillations are quickly damped. It does not happen in steel. You can see it on a simple example. Go to a steel pole and strike it with a hammer. It will ring for a minute and you could hear it a kilometer away. Go to a steel reinforced concrete pole and strike it with a hammer. Boom and that's all. That's why all our hollow steel structures are filled with concrete having certain features. Not only strength for compression and stretching, elasticity modulus, but also damping and absorption of noise. And noise comes not only from steel structures. Aerodynamics also produce noise. For example, the French TGV had a problem with current-collecting at high-speed traffic because it "whistled" very loudly. They had to develop a special design to remove this aerodynamic noise. That's why we also have a unique aerodynamics. We do not have airflow imbalances anywhere, therefore, there are no air swirls and no "whistles". Nothing will "whistle" there. It will be only a light noise, like a rustle of leaves in a forest. We do not have joints unlike with the railroad, where a wheel pounds. We shall have joints because we use rolled steel, but we shall weld them together and then grind them up. As a result, there are no level differences and no pounding. Actually, we have removed all the noise sources, including an engine, a drive as one of the sources. It should be clear that the more powerful is the engine, the more noise it generates, because this power is thrown out into the environment. We have reduced the engine power tenfold per passenger compared with the railroad. Our noise source is less, the drive power is less. Thus, we have solved this complex of problems and we know how to solve them further. I spoke about the components of noise as such, because a transport system can make noise as a whole. Therefore, we should make every element of the system not noisy. We are striving for this. However, how they work and affect each other in complex - we shall find it out while testing at EcoTechnoPark test site. We shall measure noise level there not theoretically, but practically, with appropriate instruments. I am confident that we shall reduce noise level by minimum 10 decibel compared with the most slow-speed vehicles of the second level.
Mikhail Pavlov Park, Minsk, Belarus
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