Bridge property sheet

Bridge property sheet

This window requires entry of data specified in the AUSTROADS Waterway Design Manual (1994) based on methods of the U.S. Federal Highway Administration (Bradley, 1970), which is the source of the methods used here.


If unsteady flow hydraulic calculations are being employed with the Lite or Full unsteady hydraulic models, it is necessary to provide additional data on the second page of the Bridge property sheet, with the Simplified Flow Properties tag.  As shown below, this uses values drawn from a preliminary analysis using the basic hydraulic method, which will available for this purpose when a bridge is inserted into a DRAINS model.

After performing a basin hydraulic model run, make the flowrate in the sheet shown below equal to the flowrate immediately upstream, and set the levels to those given by the preliminary DRAINS run.  If the results appear unstable with high water levels, adjust the flowrate in the Bridge Property Sheet to that immediately upstream and re-run. Hopefully, the calculated surface levels will be realistic. These can then be adjusted until the calculated levels approximate those given in the property sheet.



References:
  1. AUSTROADS (1994) Waterway Design Manual, Sydney
  2. Bradley, J.N. (1970) Hydraulics of Bridge Waterways, Hydraulic Design Series No. 1, Federal Highway Administration, U.S. Department of Transport, Washington, DC