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Bridges and Structures

New Design – Bridge Planning Hydrotechnical Design

Bridge Planning Hydrotechnical Design involves the determination of the channel characteristics, and an estimation of the hydrotechnical design parameters for a site.  These estimations are used for setting the minimum bridge girder flange elevation, culvert sizing and the riprap design for the site. 

Hydrotechnical Design documents applied during the design of the Department’s bridges, culverts and stream encroachments are summarized below.  The Environmental Management section may contain useful references when dealing with regulatory authorities during design. 

Hydrotechnical Reference Documents are also available.  Documents of particular interest include:

The Department has developed tools that may be useful during bridge planning hydrotechnical design.  These are available as described in Guide to Bridge Planning Tools.  Tools of particular interest include:

  • HIS – The Hydrotechnical Information System developed by the Department provides basic information about every bridge owned by the Department.  Information may include year of construction, size, location, documented flood observations, hydrotechnical file histories and summaries, hydrotechnical inspections, and stream profiles (based on DEM data).
  • Flow Profile – Performs 1D calculation of section averaged depths and velocities through a system of channel and structure elements.  It is based on a combination of Gradually Varied Flow and Rapidly Varied Flow calculations.  The software can be used to model multi-slope culverts and constricted bridge openings.  This is the Department's preferred hydraulics modelling tool.
  • Channel Capacity Calculator – Used to perform channel capacity calculations as per the Department’s Hydrotechnical Design Guidelines.

 Relevant Best Practice Guidelines (BPG) include:

  • BPG 5 – Bridge Assessments
  • BPG 7 – Spread Footings
  • BPG 9 – Rock Protection for Stream Related Infrastructure
  • BPG 11 – Stormwater Management at Rural Bridges
  • BPG 12 – Bridge Deck Drainage
  • BPG 13 – Freeboard at Bridges

Relevant Design Bulletins Include:

  • DB 45- Use of Retaining Wall Structures for Bridges and Roadways in Active Watercourse Environments