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What is Box Culvert?

What is a box culvert? There is no doubt that any trip from home - to the grocery, driving the kids to school, to work - puts you within eyesight of one of the many types of precast concrete box culverts. Precast concrete box culverts have many uses in civil engineering and construction applications. They are used to convey fluids such as stormwater and sewerage, for water retention, storm drainage, utility conduit, holding tanks, underpasses, service tunnels, outfalls, bridges, access ways,  and the list continues. Of all precast concrete products, box culverts could be considered the most versatile and cost effective. Box culverts come in many standard sizes, but the flexibility of their design allows for custom sizes to meet the needs of any project. The only limitation on size is transportation size and weight requirements.  Special features of a box culvert might include toe walls, headwalls, wing walls, manhole openings, pipe openings, V‑bottoms, keyed‑ends, sloped‑faced ends and water tight joints.

When considering a precast concrete box culvert versus a structure of another material (such as steel), the precast concrete box culvert offers many advantages. Precast concrete is strong and durable. Precast concrete box culverts, when made by an NPCA certified plant, ensures high quality. Also, producing the box culvert in a plant environment eliminates some of the environmental factors on job sites (temperature, poor material quality, uncertified craftsmanship, improper curing, inclement weather) that can adversely impact quality of other materials. 
High-quality sealants are used to ensure water-tightness of a precast concrete box culvert.  Precast products, especially standard size precast concrete box culverts, are readily available for immediate use. Precast concrete is an environmentally friendly material and has a long life span. Finally, being more cost effective than competing materials, precast concrete helps keep a project within budget. Install time is greatly reduced since the precast concrete box culverts are ready to install as soon as they arrive at the site.
Photo Gallery
Check out the box culvert photo gallery.

Box culverts come in many forms

Does one size really fit all? Not in Precast Concrete Box Culverts! In fact, precast concrete box culverts come in many sizes.  There are standard sizes that are commonly readily available (3' x 2' to 12' x 12' in 1' span and rise increments in 6' and 8' lengths).  Box culverts can also be designed and manufactured in custom sizes to meet project specifications.  Box culverts also come in many types to fit a variety of civil engineering and structural applications.  There are four-sided box culverts (monolithically poured), three-sided, two piece mid-seam (two three-sided structures put together to make a four-sided structure), and a crown and base (inverted "U" on concrete base foundation).

Four-Sided Box Culvert

Four-sided precast concrete box culverts are typically referred to as box culverts.  Uses of the four-sided box culvert include detention; tunnels (for conveyors, utilities, access tunnels, escape tunnels); short-span bridges (over highways, waterways, railways, golf courses); and storm drains to convey stormwater, sewage, or industrial waste.  The precast concrete box culvert has been in use for over 30 years. There are three types of four-sided precast box culverts:  monolithically poured, two piece mid-seam, and crown and base. Four-sided monolithically poured precast box culverts are poured all as one piece at the precast concrete plant and shipped directly to the job site for immediate installation. The two piece mid-seam precast box culvert is a three-sided "U" and an inverted three-sided "U" joined with sealant at the site to make a four-sided box culvert.  The crown and base box culvert is yet another way to manufacture a four-sided box culvert.  The crown and base box culvert is a precast inverted "U" that is joined to a concrete base with sealant at the job site.  The latter two manufacturing methods are just different ways to precast a four-sided precast box culvert depending on a particular plant's capabilities.

Three sided structures are U-shaped.  A three-sided structure may or may not have a crown (or curve) in the center and come in standard sizes of 8' to 48' span lengths to use for short span bridges to allow natural stream beds to remain intact.  The three-sided precast culvert is a second generation to the four-sided box culvert, being used since the mid-1980's. Three-sided culverts must be placed on concrete footers.  The flat top three-sided precast concrete culvert, like the four-sided precast box culvert needs no fill and can withstand vehicular traffic.

Three-Sided Box Culvert

Three sided structures are U-shaped.  A three-sided structure may or may not have a crown (or curve) in the center and come in standard sizes of 8' to 48' span lengths to use for short span bridges to allow natural stream beds to remain intact.  The three-sided precast culvert is a second generation to the four-sided box culvert, being used since the mid-1980's. Three-sided culverts must be placed on concrete footers.  The flat top three-sided precast concrete culvert, like the four-sided precast box culvert needs no fill and can withstand vehicular traffic.