The head of Transport Overpass Design Office Vyacheslav Babushkin shared the purposes and outcomes of the work.
The tests were taken on two types of track structures during a long period. Our purpose was to determine the dependence of metal temperature in a string rail on air temperature and environmental conditions. Mostly, we were interested in maximum readings for a specific region. Why do we need this? First of all, to design track structures with accurate temperature values to make calculations for the whole transport overpass.
How the tests were conducted? We selected a number of measurement points on top and bottom chords and planes located at a straight and skewed angle to the sun and in shadow. We utilized Testo loggers to take all measurements and then record them every hour obtaining metal temperature at the points of interest. Other parameters were measured on the local weather station in the EcoTechnoPark. These parameters included temperature and humidity of ambient air, atmospheric pressure, wind velocity and direction, precipitation, solar radiation and energy.
At the end, we found out that the overpass reaches its maximum temperature when the sun is high and releases maximum energy in the region. While the greatest temperature difference between metal and air appears upon sunset when air temperature drops sharply, the string rail gets cool much slower. The larger the structure, the slower temperature drop is. At the same time, it takes more time for heating compared to small transport overpasses. By the way, the greatest difference in metal temperature values was revealed on the flexible track structure. With a small area, it heated faster than the other ones.
The general patterns described were obvious without any study for they comply with basic physical laws. Surely, we conducted these measurements not to reach such trivial conclusions. We valued accurate data and this experiment is not the first one of a kind. We took readings in different seasons at various temperatures. In this regard, Belarus is considered a very fortunate place for our Demonstration, Test and Certification Center. Air temperature here fluctuates from +35 to -27, which allowed us to collect enough accurate data to construct transport systems in various latitudes from the Arctic to the tropics.
Unitsky String Technologies Inc. is constantly searching for options to optimize their transport solutions. Rail and string transport systems in urban, interurban and high-speed passenger or cargo implementation are being improved with the data collected in the demonstration, test and certification center. Further research will enable to develop a more reliable protection against thermal impacts, eliminate the effect of climatic factors on lifetime and loss of stability upon heating by the sun.
Ultimately, the operating principle of string transport assumes an unprecedented stability against temperature variations. Since the rail is a cutless, pre-stressed and statically indeterminate structure, temperature variations will give it more tension or slack in the limits we determine ourselves. It means that transportation will remain comfortable and safe for passengers. Therefore, this research allows us to refine the systems which, as our general designer Anatoli Unitsky often says, already comply perfectly with the physical laws. I totally agree with that. Most transport systems see temperature variations as problems but we consider them a scope for research and a possibility for further optimization.