[georgie]

A bascule bridge is a moveable bridge with a counterweight that continuously balances the span, or "leaf," throughout the entire upward swing in providing clearance for boat traffic. Bascule is a French term for seesaw and balance, and bascule bridges operate along the same principle. They are the most common type of movable bridge in existence because they open quickly and require relatively little energy to operate.

Bascule bridges may be single or double leaf. Double leaf bridges usually have any truss structure and counterweights below the deck, while a single leaf bridge is typically a truss bridge with an elevated counterweight.

History..

Although the bascule bridge has been in use since ancient times, it was not until the 1850s that engineers developed the ability to move very long, heavy spans quickly enough for practical application. The Blagoveshchensky Bridge across the Neva River in Saint Petersburg was the first large bascule bridge, opened in 1850. Since then, all bridges across the Neva and other major rivers in the city (21 in total) were bascule to facilitate navigation, which prevented the city's inhabitants from traveling across the river at night (this remained so until 2003 when the first cable-stayed bridge across the Neva was opened).

Design...

Counterweights may be located above the bridge or below the deck of the bridge. There are two common designs of bascule bridge. One is the fixed-trunnion bascule design, which is where the bridge rotates around a large axle called a trunnion to raise. This bridge type is sometimes called the 'Chicago bascule' as this type was developed and perfected there and is used for many of that city's river crossings. Joseph Strauss was a key person who worked on improving the trunnion bascule bridge. Another form of bascule bridge is the Scherzer rolling lift, also known as a Rolling Bascule Bridge. The city of Joliet, Illinois has a number of this structure type. The Scherzer rolling lift bridge essentially rolls or rocks like a simple rocking chair on a track to raise.

the final piece in my explore of the stanley dock complex is now complete
its been along time coming and im glad ive finally done this....

explored with kevsy21 (sorry for smoking all your ciggys lol)

firstly a few pics of remaining bridges in the east float birkenhead




and now liverpools answer (the smallest of the 3)





























a nice warm anyone?





a plan of the whole circuits and layout found still hanging on the wall

[54Strat]

Smart stuff. I've often wondered about the machinery inside them, thanks for sharing.

[georgie]

heres to a little night climb a while back (bit blurry some pics)

[tristanjay]

Finally someone got in one, top stuff chaps been hankering to see inside that one for years.

[pacef8]

excellent, i never new they had so much gear inside them!! i take it the counter balance is concrete and not shot or sand.

[Minxy]

Brilliant stuff georgie

[sallybear]

Brilliant, made my day seeing inside this. Cracking report

[georgie]

cheers folks im glad i finally got to see inside after many yrs of wondering

[tarboat]

Very nice work. I too really wanted to see inside this.

[Gone]

Brilliant mate