Truss Bridges- what kind to build

[Mdcastle]

A question was raised on another forum:

What's goes into the decision of whether to build a deck truss vs a through truss? Are there tradeoffs of cost, maintentence, does the specific site factor in someohow. Or is it just what they think looks nice or are used to building. Do deck trusses tend to be newer and through trusses older, and if so, why the shift.

What is going on structurally on a truss? Is most of the load carried by the member adjacent to the deck and the rest of the structure mainly to stiffen it and counteract the tendancy to bend?

[bugo]

When was the last deck truss built?

[roadman65]

It is a shame that the old Warren Truss has become obsolete in design, as those trusses were so cool.  NYSDOT demolished many over the years, but ocassionally you still see a few left in the Empire State.

If I was a modern thinker, I would go for the prefabbed concrete deck for viaducts over 20 feet tall.  If it were a perfect world, the Warren Truss in a series for  wide rivers for low lying crossings would still be my choice.  For smaller  river crossings the Parker Truss would be if the standard girder structure could not work.