Forest Road Engineering Guidebook - Ministry of Forests

Forest Road Engineering Guidebook
Design requirements for bridges and stream culverts
The design of bridges and stream culverts encompasses more than the design
of structural components. A bridge or stream culvert design should consider
the composition and interaction of all the components, as well as their relationship
and impact to the users, road, and stream. A bridge comprises the
superstructure, substructure, connections, vertical and horizontal alignment
controls, approach road fills, and scour protection works. Similarly, a stream
culvert comprises the culvert materials, compacted backfill, scour protection,
and roadway. Bridge or stream culvert designs include, but are not limited to,
consideration of:
• user safety
• site selection
• environmental integrity
• fish habitat and passage
• impact of proposed structure on stream during and after construction
• site revegetation requirements
• structure alignment and location (vertical and horizontal) relative to the
road and stream channel
• complete structure combination (substructure, superstructure, connections,
and scour protection)
• suitability of selected foundations for the specific site
• design flood development
• navigation (Navigable Waters Act)
• debris potential and passage
• scour protection
• design vehicle configuration for load and alignment
• design service life influence on selection of bridge type and composition
• construction layout, methodology, and timing
• economics.
Bridge and major culvert design responsibility
Bridge designs should clearly identify who is taking overall design responsibility
(whether a professional engineer, professional forester, or nonprofessional)
for ensuring that all aspects of the design have been appropriately
addressed. In addition, a person required to prepare a road layout and
design must ensure that a professional engineer takes design responsibility
for major culverts.
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