St. Petersburg is considered one of the most beautiful and romantic cities, not only in Russia, but throughout Europe. Largely due to drawbridges. Thousands of tourists come annually to see this miracle of engineering. Why are bridges being built in St. Petersburg and other cities of the world? How are they arranged and how do they function? Read about it in the article.
Drawbridges and their main types
So what is a drawbridge? This is a special kind of bridge with moving spans. They are built, as a rule, in cities, on important transport channels or rivers.
Why are bridges being drawn? The answer is simple: so that large vessels can freely pass through the navigable canal or river bed. At this time, of course, the movement of land vehicles on the roadway of the bridge is impossible.
Today there are several options for drawbridges:
- Lifting (widely used in medieval fortifications).
- Classic drop-down (examples: Tower Bridge, Palace in St. Petersburg).
- Swivel (Varvarovsky bridge in Nikolaev).
- Vertical lifting (Kuzminsky and Finland bridges).
- Folding (Hornbrücke in Germany).
- Flooded (two bridges on the Corinth Canal).
A special kind is a folding bridge. He is able in just a few minutes to "curl up" into the wheel and free up the passage for a boat or boat. A bridge of similar construction is thrown across one of the canals of London.
How do drawbridges work?
The set of equipment that the drawbridge is equipped with depends on its type and weight. Typically, such designs are equipped with three drives: the main electro-hydraulic, backup (operating from an internal combustion engine) and manual emergency. In addition, all drawbridges are equipped with braking devices that can stop the passage of flights at any point.
Each bridge has its own control panel. It is located so that the operator can freely inspect the entire situation on the river. When a command arrives, the responsible employee presses the button and multi-ton spans slowly rise up.
The largest number of drawbridges is on the Chicago River (38), as well as on the Neva (19).
Drawbridges of St. Petersburg
"Why are bridges being drawn?
In the capital of the northern nights
Lights are hiding in the mists
Streets of Broken Lights ”
With these words one of the songs of the famous Russian band Belomorkanal begins. In total, there are two dozen drawbridges in St. Petersburg. Perhaps the most popular of these is the Palace Bridge, which connects the Spit of Vasilyevsky Island with the Admiralty Island. His image is considered one of the main tourist symbols of St. Petersburg. The drawbridge mechanism lifts up massive spans weighing 700 tons. How this happens - see the following video:
Tourists note. The construction of bridges in St. Petersburg is carried out only during the period of river navigation (end of April - mid-November). At the same time, bridges are not bred if the wind speed exceeds 15 m / s, as well as at an air temperature of more than +25 degrees Celsius.