bascule brige

[Shilshole]

The key phrase there is the geometry of the counterweight.  The ones I've seen only rotate to 60 degrees or so.

Right, and where the counterweight is.  Compare the counterweight geometry and height of the GN bridge, which has a max of about 60 deg (note remaining clearance between bottom of counterweight and railhead), at
<http://en.wikipedia.org/wiki/Image:Salmon_Bay_Bridge-2Clip.jpg>
vs. those of the 80+ deg of a highway bridge with above-grade counterweight at
<http://en.wikipedia.org/wiki/Mystic_River_Bascule_Bridge>
and the 80+ deg of a Chicago-type bascule at
<http://en.wikipedia.org/wiki/Fremont_Bridge_%28Seattle%29>.

Sixty degrees may be sufficient in the OP's case;  the max lift only has to be in the center of the channel (and persumably the span) since that's where a ship's superstructure is highest, and he already has some elevation above the surface it's planned to span.  If the railhead grade were closer to the water surface, he'd have to go closer to vertical on opening.

The NP used to have a single-track bascule, crossing the Lake Washington Ship Canal on a rarely used industrial branch, that was similar in design to the first pic.  Because the deck was closer to the water surface, its short but wide counterweight permitted a nearly vertical aspect in the open position.

[nbrodar]

The key phrase there is the geometry of the counterweight.  The ones I've seen only rotate to 60 degrees or so.

As to the catanary question, that's a toughy.   I'll have to do some research, but I think most movable bridges in electric territory are lift bridges.   It's easier to rig the catanary to go straight up and down, rather then having it rotate.

Nick

 

[Shilshole]

I have a problem that is I need a curved brige but as I know now thats not ideal ...

Not only not ideal, but curved lifting spans won't work.  Or did you mean a straight lifting span with curved approaches?  If the latter, the curved approaches can be of almost any style, fill or pile trestles or plates, with a straight roller bascule lifting section.  The width of the counterweight section may have to be increased to accommodate the curved approach.

[Shilshole]

Most bascule bridges I've seen don't lift high enough to clear modern commeral ships.

???
Maybe you're thinking of another type of bridge?  The bascule span can rotate to nearly vertical, depending on the geometry of the counterweight and whether the counterweight is above the deck or, as in the Chicago-type bascule, the counterweight rotates through the piers.

[S&G Rute of the Silver River]

The height from the water is two highcube cars stacked to the bottom of the ties. I'm planning on tugs with barges from the turn of the sentury to the forties. I thought it would be like the one in Railroad Model Craftsman tm in Nov. 2003 issue. I don't think a vertical lift would work becouse I use electric locos that seems a pain to rig.

[nbrodar]

What size ships will be passing through your canal?  And what era?  How close is your track to the water?

Most bascule bridges I've seen don't lift high enough to clear modern commeral ships.  Fishing vessels, barges with tugs, and pleasure craft sure, but not freighters, tankers, container ships or naval vessels.   If any of these commerial vessels ply your canal, a vertical lift bridge might be better.  If you intend on scratchbuilding, it might be easier to contruct as well.

Nick

 

[S&G Rute of the Silver River]

See its almost a canall I crossing so I cant have any piers in the center. I'd just build the thing from a plate deck gurder brige. anf it dosent swing but teloscopes inside of itself.

[whitman500]

This might be a minor point in how to solve the problem but I believe Walthers still makes a swing bridge but that its bascule bridge has been retired and is rather hard to find (though sometimes they show up on Ebay).  All else being equal, you might as well go with the bridge for which a kit exists than for one that will require scratchbuilding (unless you really like scratchbuilding).

[nbrodar]

With curving approaches, a verticle lift or swing bridge would most likely be used.

Nick

[fwright]

I would think a swing bridge would be easier to implement (especially with a curve) and more likely to be used in the prototype.  I've even seen a prototype of a 1/2 swing bridge where only 1 end swings from the pivot point.

my thoughts, your choices

Fred W

[S&G Rute of the Silver River]

I have a problem that is I need a curved brige but as I know now thats not ideal but I think i found a soution in a rail roller bascule brige. Works not unlike a drawbrige( it lifts one edge and drops the other allowing it to roll under the abutments leaving room for ships structures to pass.) I just need to rework the curve. Any recomendations, thoughts, comments, etc. Much apricated.