Section 2 - Getting Started

NOAA ATLAS 14 DATA

TERRAIN DATA

CREATE DRAINAGE MODEL

SET DEFAULTS AND CONSTRAINTS

PROTOTYPES

 

The designer should compile the information and material necessary to complete a drainage design. Most commonly needed items for a drainage design (existing or proposed) are storm data and terrain data for the project.

NOAA ATLAS 14 DATA

The Department’s Hydraulic and Drainage Unit advises the designer to use the NOAA Atlas 14 data, which can be accessed through the NOAA ATLAS 14 POINT PRECIPITATION FREQUENCY ESTIMATES webpage in conjunction with the CTDOT Drainage Manual.

Follow the direction on the NOAA Atlas 14 webpage and directions given by CTDOT Hydraulics & Drainage unit on how to develop the Point Precipitation Frequency (PF) Estimates, which can be downloaded in CSV-format and opened with Excel.  The data in the PF tabular format will be used for Storm Data to create a User Defined IDF Table.

Scroll down the webpage, making sure CSV format is set to: Precipitation Frequency Estimates and click Submit.

Either select Open, Save or Save As, (save to Project directory).

The Excel file will be used to create an IDF-Table for the projects storm data. The options available to create an IDF-table will be covered later in this manual.

TERRAIN DATA

Drainage and Utilities uses the terrain model referenced into a DGN file to display the storm drainage and other utilities in 2D and 3D models. Drainage structures and conduits are fully integrated in graphic and database functions. The data is in the graphics within the design file (*.dgn file).

Drainage and Utilities can use the elevations from the active terrain, but Drainage and Utilities can only work with one terrain; this can make it necessary to merge terrains such as existing, LIDAR, point clouds and/or proposed into one terrain. The designer should create a specific “drainage terrain” for use with the drainage layout and calculations.

To merge two or more terrains, add Lidar data the user should visit Bentley Help - Terrain Edit.

This “drainage terrain” is in its own MicroStation DGN file and is referenced into the “drainage” MicroStation DGN file.

CREATE DRAINAGE MODEL (DGN file)

Ensure OpenRoads Designer Connect Edition is set to the correct Workspace and Workset. Create a new *dgn file (2D) exclusively for your storm drainage layout, calculations, and utility conflicts, follow the CTDOT CONNECT DDE Manual – Volume 3 – Module 1 – Creating Base Model Files.

1.  From the New dialog box, browse to the proper discipline folder, enter the file using Civil Design CAD File Naming Conventions (Volume 16 – Appendix – File Naming), DD_DC_PROJ_NUMB_Description. 

Example: HW_CB_1234_1234_ProposedDrainage.dgn

2.  Change the workflow to: Drainage and Utilities (upper left corner), open the Drainage and Utilities Model within the Explorer dialog box. 

3. From the Home tab use the Attach Tools - References to attach the survey, terrain, aerials, and design files as needed. Turn OFF Levels as needed from the individual files.

4.  Set the Active Terrain. Using the Element Selection tool click on the boundary line for the terrain, hover over it, select the tool Set As Active Terrain Model, this will make the terrain active and will be used for placing the drainage structures.

5. In the 2D view (Default) override the Symbology and turn off triangles. Open the Default 3D view and set-up as needed to your preference.

6.  Save settings.

7. The Drainage and Utilities Hydraulic Engine needs to be activated. From the Layout tab, select the Place Node command. This has to be done once per DGN file to activate the utility model and to create the hydraulic project. Only one hydraulic project per dgn file, but multiple systems can be place and calculated.

 

The You Cannot Undo This Action message box will open, click Yes. This will open and prepare the Drainage and Utilities project in your DGN file, some context menus will pop-up and disappear, wait until completed and your cursor comes back. Now you are ready to place your structures, conduits, catchment areas and do your calculations.

SET DEFAULTS AND CONSTRAINTS

Some project specific properties, defaults and constraints need to be reviewed and set for each project, where possible CTDOT standards have been set. 

1.  Click on the Tools tab and select Options - Drainage. The Options box opens.

• Hydraulic Model tab: Pipe Length – Use 3D Length?  is unchecked.
• Units tab: Default Unit System for New Project is set to: US Customary, make sure all units are set correctly.  Such as rainfall intensity is set to the intervals as shown on the NOAA PPF Estimates.

      Click OK.

2.  Click on the Analysis tab and select Default Design Constraints.

The constraints have been set to follow the CTDOT Drainage Manual where possible. If you want Drainage and Utilities to design your drainage system, it is especially important to review, edit and make changes to follow design standards for the individual project, such as maximum spread. The Drainage and Utilities Help menu should be used for each specific explanation of the Default Design Constraints topic.

 

 

PROTOTYPES

Click on Components – Catalog - Prototypes.   

Prototypes allow for entering default values for elements in a drainage network and are used to define the hydraulic properties of features. A prototype works in cooperation with element templates and feature definitions to define the characteristics of a drainage feature. The most widely used conduits, gutters, catch basins, manholes, cross sections, catchments, and headwalls etc. have been set to CTDOT Standards. 

Some properties are project specific and should be edited as an individual item within the items Hydraulic Analysis. It is important the engineer reviews and edits these to fit project needs. See the Bentley Help menu for further explanation of the prototype settings.