Currently ORD does not have an option to calculate Time of Concentration for the channel flow that the state of Oklahoma uses. This eliminates the option to use the programmed Tc calculator for channel flow. I need an option to put in my own formula or have Bentley include it in the workspace. OK DOT currently uses the following:
Tf= k'(Lf^0.77)/Sf^0.385
Tf=Time of Concentration for channel flow
Lf= Channel Length
Sf= Channel Slope, ft/ft
k'= Dimensionless coefficient
Channel Type and k' Values:
Straight, clean stream, k'=0.00592
Average stream, few obstructions, k'= 0.00835
Meandering stream with ponds, k'= 0.01020
V-ditch, k'= 0.01252
| Civil Product Used | OpenSite Designer, OpenRoads Designer, OpenRail Designer |
My post about this topic has been merged to this one, it is extremely important that we get the Oklahoma Department of Transportation's time of concentration method added into the software! Please find a PDF of the necessary pages from the Oklahoma Department of Transportation's Roadway Drainage Manual on my post.
If Bentley were to include a Time of Concentration formula selection that is common to DOTs as an option for the time calculation within OpenRoads Designer program, I think it would make a significant improvement and reduce the amount of repetitive work required by the Oklahoma DOT.
The Maine DOT Design Guidance for Hydrology is attached with Time of Concentration on pages 3 and 4.
Is there a design guide for Maine DOT that describes the methods for Calculating the ToC? If there is, and you can attach it, that would be helpful - thanks.
Maine DOT also uses it's own methods for calculating Time of Concentration. Having the ability to add a formula would be a time-saver.