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

What is a Culvert?

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

Culvert Components

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

Plan View

Road Cover Rise Burial (Embedment) Span Haunch XS View

Culvert Shapes Round Ellipse Arch Box

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

Culvert Materials CSP SPCSP WSP CIP PC Plastic

38 37 40 40

Culvert Material in AT System SPCSP CSP CIP PC Plastic WSP

Culvert Size in AT System

Culvert Age in AT System

Culvert Design and Construction

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Culvert – Pros / Cons

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

Bridge Preferential Icing

Bridge Barriers

Unstable Valley Walls

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

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

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

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)