Input Bridges

[michaeloconnell]

Hi,
I'm new to RiverCAD but am finding it difficult to understand the process of inserting bridges. I'm using RiverCAD XP in AutoCAD 2007. I have read and re-read the manual but I'm still getting stuck.
I've a few questions which I hope someone can answer:
1) What is meant by the "low chord flow structure geometry"? Is this the bed level of the river under the bridge?
2) Do I need to create a section for both the upstream and downstream ends of the bridge? The manual seems to suggest I only need the downstream end but the program seems to me at least to want a section at the upstream face of the bridge also.
3) I have developed a cross section at the downstream end of the structure and have defined geometry for it as the downstream end. However, it then looks for the roadway elevation at the next section upstream. I then create a cross section at the upstream face. I give it roadway elevation data by editing the cross sectional data. Am I on the right track?
Thanks,
Michael.

[Chris Maeder]

Note that the definition of a bridge opening is dependent upon if you are using HEC-RAS or HEC-2. If you are using HEC-2, then it is further dependent if you are wanting to construct a Special Bridge or Normal Bridge.

RiverCAD handles all of these, and by convention you simply "declare" the structure at the downstream face cross section of the bridge opening. RiverCAD then will fill in all of the remaining details--as long as you know what the details are.

Note that there are tutorials for both HEC-RAS and HEC-2 bridge structures. However, if you are having difficulty, please call our technical support team toll-free at 800-488-4775.

Chris Maeder, M.S., P.E.
Senior Technical Engineer