This course is for designers who wish to use 12d Model for the design and analysis of Stormwater Drainage Systems for urban and highway drainage. It is intended for people competent in the basics of 12d Model, who have an understanding of the concepts of stormwater drainage hydraulics and hydrology.

The first day of training covers creating the stormwater drainage network, modelling other utility services and checking for clashes, labelling the network, and producing plotted output for use in drawings.

The second day focuses on the hydrological and hydraulic design and analysis of the network.  In our public training sessions we use 12d Model’s Dynamic Analysis Engine for analysis, if the course is done in-house, we offer the choice of analysis in 12d Model or in Drains.

Prerequisites: ‘Introduction to 12d Model’ or good working knowledge of 12d Model. Understanding of design concepts related to Stormwater Drainage design.


At the end of the course, participants will be familiar with the use of 12d Model for creation of stormwater drainage networks, and for ensuring that the network does not clash with other utility services.
Participants will be familiar with the Hydrological and Hydraulic models available in 12d Model, and have designed and analysed the network using both Rational and Ilsax hydrology and HGL check hydraulics.

12d Model’s Dynamic Wave Routing hydraulic model will have been used to analyse a detention basin and overflow weir.

Course Summary


This session covers the creation of a network of pits and pipes for stormwater drainage, and creation of other necessary inputs to the design process.
The session introduces the Drainage Network Editor (DNE) as the main tool to size and grade pipes, set cover levels, and as the entry point for plotting and analysis.

Specific elements covered in the first day are:-

  • Setting up a combined Finished Surface from road design and survey data.
  • Locating (and marking) low points on the road design strings.
  • Creating a network of pits and pipes, and grading the network using the Drainage Network Editor.
  • Assigning pit names and labelling the pits.
  • Identifying the parts of the road design relevant to the drainage design and creating a ‘road design file’ that lists these strings.
  • Labeling the network with linestyles and symbology suitable for presentation drawings or export to CAD.
  • Modelling underground services (water mains and utility duct banks) in 3D, and checking for clashes between the services and the drainage lines.
  • Adjusting the invert levels of the pipes to ensure clearance to other services.
  • Introduction to 12d Model’s use of Attributes, and how attributes on the drainage network are used to produce reports/setout tables and the like.
  • Creating longsection plots of the network


This session follows on from the material covered in Day 1, and covers the techniques for hydrological and hydraulic analysis and design of the network.

  • Creating catchments, measuring areas, and the automatic and manual methods of assigning catchment areas to pits.
  • Defining bypass flow routes, and how these are used to analyse width of gutter flow and ponding at sag pits.
  • Defining inlet rating curves for pits.
  • Using drafted flowpaths, to calculate Tc values.
  • Using 12d Model to calculate Ku and Kw factors.
  • Analysing the system using 12d Model’s Rational Hydrology Engine.
  • Calculating the HGL, and determining pipe flows and velocities.
  • Calculating bypass flows and ponding depths at sag pits.