1. What is a Culvert?
Culvert Components
Culvert Design and Construction
Culverts – Pros / Cons

2. What is a Culvert?

3. CHBDC AT Buried Structure Bridged Opening – 3m span
Design – soil interaction AT
Surrounded by Soil
Below Road
Parallel to Stream
>= 1.5m DIA flow area

4. Culvert Components

5. Elevation View Invert Streambed Road Rock Bevel End Cover Inlet Outlet
Barrel
Burial
(Embedment)
Clay Seal
Crown
(Obvert)
Elevation View

6. Plan View

7. Road
Cover
Rise
Burial
(Embedment)
Span
Haunch
XS View

8. Culvert Shapes
Round
Ellipse
Arch
Box

9. Culvert Shape in AT System
Arch
Ellipse
Box
Arch
Box
Ellipse
Round
Round
All (~2820)
> 1999 (~380)

10. Culvert Materials
CSP
SPCSP
WSP
CIP PC
Plastic

11. 38 37 40 40

12. Culvert Material in AT System
SPCSP
CSP
CIP PC
Plastic
WSP

13. Culvert Size in AT System

14. Culvert Age in AT System

15. Culvert Design and Construction

16. Soil Steel Structures – No backfill
Steel culverts are soil-steel structures:
Without compacted backfill, they will not carry the load
The culvert will buckle and fail if not supported

17. Soil Steel Structures – Compacted backfill
Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

18. Wide, Low Cover Acts like Bridge Costs like Bridge
Structural enhancement for wide shape, low cover (ABC shown)
Cost similar to bridge

19. Pipe Arch High Stress Compaction?? Low Resistance Bulging
Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

20. Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

21. Open Bottom Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

22. Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

23. Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

24. Base Preparation Geotextile used to stabilize soft foundations
Typically woven geotextile (stronger, less flexible) for stabilization
Add cushion layer of crush granular on top of geotextile to minimu=ize puncturing by equipment

25. NO CAMBER
Camber – longitudinal pre-shaping
Use in high fill cases
Predict settlement and build in, so linear slope results in time

26. Assembly – Side Plates
Side plates, roof plates, and bevel ends can be pre-assembled off to the side while the floor plates are being assembled
Side plates are attached to the floor alternating side to side to minimize spiralling from eccentric loads

27. Assembly – Roof Plates Check Dimensions Control Shape
Roof plates are then added
After 2 complete rings – check dimensions
Control shape with cable stays and/or scaffolding
Check Dimensions
Control Shape

28. Backfill - Haunch Haunch – tight area between bed and sidewalls
Critical to structural integrity of pipe
Filled with crush granular, small handheld compaction equipment
If high pressure water jetting, need appropriate nozzle pressure and application pattern

29. Backfill - Sides
Above haunches – still use small equipment (minimize stresses on pipe)
Spread and compact in 150mm layers
Keep balanced (within 300mm) on both sides – avoid distortion, rolling)
Move equipment parallel to the pipe

30. Concrete End Treatment
Purpose:
Reinforce bevel ends
Resist uplift forces
Prevent piping

31. Culvert – Pros / Cons

32. Cost Culvert = $1000/m2 * pi * L * D Bridge = $4000/m2 * L * W Culvert
Ratio D L
Cost W 2 40
250,000 14 10
560,000
0.45 3
375,000 15
600,000
0.63 4
500,000 16
640,000
0.78 5
625,000 17
680,000
0.92

33. Bridge Preferential Icing

34. Bridge Barriers

35. Unstable Valley Walls

36. Need Soil Support Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

37. Channel Work Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

38. Blockage - Drift/Icing
Steel culverts are soil-steel structures:
With compacted backfill, the soil will prevent buckling

39. Hydraulics, Fish Passage ????
Pros
Cons
Cost
Need Soil Support
Preferential Icing
Channel Work
No Barriers
Drift, Icing
Unstable Valleys
Hydraulics, Fish Passage ????
Note: Selection of crossing structure is based on an optimization process involving assessment of a range of options (see Bridge Conceptual Design Guidelines)