GEM Triangular Culvert

Ranked #1 in culvert competition (Approved for use by Alberta Transportation Engineers in Canada). 


Photos of installed culvert at the conclusion of this document. Field trial for Alberta Transportation Engineers to prove claims of the GEM Culvert.


The GEM Triangular Culvert(Patent's and Patent's pending) has many environmental impact and hydro-flow advantages over the old technology culverts (Round & Box). To the best of our knowledge the GEM Triangular Culvert is the only culvert designed that has been  tested using Auto-Desk software.  The software was used to test structural and flow capabilities, and compare our technology with the old traditional round and box culvert designs.  GEM Triangular Culverts are engineered and designed according to site requirements and hydrology reports, common to the industry.

A bridge culvert is designated by the entrance or exit dimensions. A round culvert equal to 5’ (approx. 1500 mm) or greater. The entrance or exit area will be π r² or π(5’÷2)² or 19.625 sq. ft. or greater.
Metric – 5’ or 1.524 meters or 1.82 sq. meters or greater.

A non-bridge culvert is less than a 5’ round culvert entrance or exit cross section.

GEM Culvert is approved for use in Alberta and is on the Alberta Transportation Supply List. 19.02ft² or 1.767 m² cross section or less is approved for use in Alberta, Canada.

The GEM Triangular Culvert with 19.02ft² cross section will out perform a 9foot or 2700 mm round culvert for flow.  

A GEM Triangular Culvert with designed entrance flows at over 10.0 cu.ft./sec by computer simulation.
A Gem 6’ culvert is 15.59 sq. ft. or 1.44 m² therefore a non-bridge culvert but has the flow of in excess of an 8’ round bridge culvert, proven by computer simulation and a field trial in
M. D. #133 of Alberta, Canada. (third party test) This is one of many advantages that we call the “GEM Advantage”. (View Photos)

GEM Triangular Culvert:

Non-bridge culvert - 6’ with designed entrance 150 cu. ft./sec slightly more flow then an 8' round culvert excluding head pressure. 

The GEM Triangular Culvert will have a lower profile above the static water level compared to the Round Bridge Culvert of similar flow that is properly installed, with engineered materials and design. This results in a cost saving by minimizing road grade alterations.

When selecting a GEM Triangular Culvert engineering flow analysis will be used for the appropriate size selection. GEM Triangular Culverts are manufactured out of environmentally friendly products, designed for low maintenance minimal environmental impact and maximum longevity. Our Gem Triangular Culvert has many advantages over the old technologies of round and box culverts.  The non-polluting construction maintains minimal erosion on the environment and has low heat transfer therefore an excellent choice for sensitive environmental areas, such as permafrost conditions.  Our advantages are numerous, as we appear to be superior in 32 of 33 aspects of a culvert derived by experts in the industry and placing 2nd in the weight category competing against round concrete & steel culverts and concrete box culverts. This indicates the GEM Culvert to be the superior and ultimate choice in road construction culvert selection. Engineering and documentation can be provided by the GEM Team on request.  

Advantages of the New and Innovative Technology of the Pre-cast GEM Triangular Culvert:

Culvert designs are ranked by superiority in various categories with numbers 1 to 4, with one having top ranking.  Generally all rankings are validated by computer simulation, field testing and experienced professionals.  In testing all technologies GEM Holdings, has found the Autodesk Software to be useful and accurate and field tests have validated simulation results.

  1. Structural Strength
  1. GEM Culvert (using 10” of concrete)
  2. GEM Culvert (using 6” of concrete)
  3. Box Concrete Culvert (using 10” of concrete)
  4. Round Concrete Culvert (using 10” of concrete)
  5. Round Steel Culverts (using 3/8” galvanized steel)

2. Quick Assembly and Ease of On-site installation, resulting in time savings. 

  1. GEM Culverts (Using the Innovative GEM Substructure)
  2. Box Concrete Culvert
  3. Round Concrete Culvert
  4. Round Steel Culverts (multi-plate type)

 3. Ease of Compaction

  1. GEM Culverts (Triangle easier to compact then a round or box design)
  2. Box Concrete Culvert
  3. Round Steel Culverts
  4. Round Concrete Culvert

 4.Ease of Inspection 

  1. GEM Culverts (3 independent components – fewer stress fractures in corners and at low water grade, total culvert visible)
  2. Box Concrete Culvert
  3. Round Concrete Culvert
  4. Round Steel Culverts

5.Low profile to accommodate flood conditions where elevating the grade is expensive or not feasible

  1. GEM Culverts
  2. Box Concrete Culverts
  3. Round Steel Culverts
  4. Round Concrete Culverts

6. High water transfer at low flow conditions

  1. GEM Culverts
  2. Box Concrete Culverts
  3. Round Concrete Culverts
  4. Round Steel Culverts

7. High water transfer at annual flood conditions

    1.  GEM Culverts (highest velocity)
    2. Box Concrete Culverts
    3. Round Culverts

8. High water transfer at full flow flood conditions with equal entrance area

  1. GEM Culverts – highest velocity
  2. Box Concrete Culverts
  3. Round Concrete Culverts
  4. Round Steel Culverts

9. High Durability

  1. GEM Culvert (using 10” of concrete)
  2. GEM Culvert (using 6” of concrete)
  3. Box Concrete Culvert (using 10" of concrete)
  4. Round Concrete Culvert (using 10"inches of concrete)
  5. Round Steel Culverts

10. Weight Advantage

  1. Steel culverts
  2. GEM Culvert (using 6” of concrete)
  3. GEM Culvert (using 10” of concrete)
  4. Round Concrete Culvert (using 10” of concrete)
  5. Box Concrete Culvert (using 10” of concrete)

11. Advantageous in freezing conditions (Photograph #2)

  1. GEM Culverts (ability to absorb expansion forces with stress relief at corners and panel ends also culvert is usually empty in winter photo#1)
  2. Round Steel Culverts
  3. Round Concrete Culverts
  4. Box Concrete Culverts

12. Cost Effective for Compaction

  1. GEM Culvert (using 6” concrete able to use aggregates consistent with road building material)
  2. GEM Culvert (using 10” concrete able to use aggregates consistent with road building materials)
  3. Box Concrete Culvert
  4. Round Concrete Culvert -intensive installation procedure
  5. Round Steel Culverts – shorter life expectancy with intensive labour assembly, and intensive installation procedure

13. Mechanical Seal – unlike individual seals as found in round and box modular culverts – locks together but can move at apex.

  1. GEM Culvert (unique Technology – used in 6” concrete culvert)
  2. GEM Culvert (unique Technology – also used in 10” concrete culvert)
  3. Round Steel Culverts
  4. Round Concrete Culvert
  5. Box Concrete Culvert

14. Advantages in Permafrost (new technology) that limits thermal conduction, and is installed level to grade therefore, no requirements for steaming, lower maintenance, therefore dollar savings.

  1. GEM Culverts
  2. Box Concrete Culverts
  3. Round Concrete Culverts
  4. Round Steel Culverts

15. Wildlife accommodation and design to accommodate fish survival with a greater base area also water retention in erosion plates.

  1. GEM Culverts (sheltered corners for smaller animals)
  2. Box Concrete Culverts
  3. Round Concrete Culverts
  4. Round Steel Culverts

16. Wider water dispersal area, therefore reducing the need for expensive rip-rap for erosion control, accommodating high velocity water flow and downstream land purchase (off right of way).

  1. GEM Culverts (rapid energy dispersal, usually within right of way)
  2. Box Concrete Culverts
  3. Round Concrete Culverts
  4. Round Steel Culverts

17. Reduced Water Control Cost due to rapid assembly (reference to transfer of water across stream bed).

    1. GEM Culvert (using 6” concrete)
    2. GEM Culvert (using 10” concrete)
    3. Box Concrete Culvert
    4. Round Concrete Culvert
    5. Round Steel Culverts

 18. Longevity

    1. GEM Culvert – (using the 10” concrete culvert and section ends) has a single surface deflection site, with stress relief in corners and panel ends
    2. GEM Culvert – (using the 6” concrete culvert and section ends) has a single surface deflection site, with stress relief in corners and panel ends
    3. Box Concrete Culvert
    4. Round Concrete Culvert
    5. Round Steel Mufti-plate culvert (Life expectancy 20% to 40% of structural concrete)  

19. Longevity - due to rust inhibited micro rebar for structural quality, depending on the purchase order, as well as stress relief in the corners and panel ends, which reduces Concrete fractures or cracking with stable sub-grade. Longevity will also be increased with concrete additives and corrosion inhibitors, this will eliminate the use of corrosion inhibiting coatings as used on metal culverts that have a limited life expectancy.

    1. GEM Culverts (have corrosion inhibited rebar and non-corroding components) (Concrete additives)
    2. Box Concrete Culvert (individual components in end to end connection)
    3. Round Concrete culvert (individual components in end to end connection)
    4. Round Steel Culvert (corrosion of galvanized polluting metal, subject to deforming due to lack of structural stability)

20. Flow increase due to function of inlet design - (validated by simulation and field testing of the Box Concrete Culvert and the GEM Culvert)

    1.  GEM Culverts use a 60° wall, therefore reducing vertical force efficiency loss as would occur in a 90° wall.
    2. Box Concrete Culvert with its’ inlet design, using a 90 degree vertical wall as described in (Ref. a) testing
    3. Round Culverts inability to install an efficient inlet design

21. Maintenance (due to compaction failure)

    1. GEM Culverts - less road aggregate deflection due to superior aggregate compaction.
    2. Box Concrete Culvert - 2 deflection sites
    3. Round Steel Culvert – limited uneven compaction and larger deflection site
    4. Round Steel Culvert limited uneven compaction and larger deflection site

22. Ease of Removal off site to new location

    1. GEM Culverts – no bolts or fasteners with designed lift sites
    2. Box Concrete Culvert
    3. Round Concrete Culvert
    4. Round Steel Culvert

23. Extending Culvert due to design changes – or requirements

    1. GEM  Culverts
    2. Box Concrete Culvert
    3. Round Concrete Culvert
    4. Round Steel Culvert

24. Installing culvert without temporary road construction

    1. GEM Culverts
    2. Box Concrete Culvert
    3. Round Concrete Culvert
    4. Round Steel Culvert

 25. Water control during installation without temporary construction

    1. GEM Culverts are installed at grade level (low water level)
    2. Box Concrete Culvert (below water level to accommodate erosion concerns)
    3. Round Concrete Culvert (below water level to accommodate erosion concerns)
    4. Steel one-piece Culvert (below water level to accommodate erosion concerns)

26. Reduced need for replacement therefore reduced costly disturbance of pavement or roadways.

    1. GEM Culverts
    2. Box Concrete Culvert
    3. Round Concrete Culvert
    4. Round Steel Culvert

27. Surface deterioration due to lifting caused by dynamic forces from loads

    1. GEM culvert primarily reflects, or directs the forces downwards relative to the surface at approximately 15° to the horizontal.
    2.  The round culverts deflect 45° or ½ of their exposed surface to the dynamic forces upward to the surface, increasing at the apex
    3. The Box Concrete Culvert deflects the total dynamic forces exposed to the top of the culvert upwards to the road surface at 45°
    4. The static load or point load of the triangular shape is superior to the round or box designs

28. Water flow efficiency relative to entrance area

    1. GEM Culverts 11% flow increase plus entrance design
    2. Box Concrete Culvert 5% flow increase plus entrance designs
    3. Round Concrete Culvert 1% flow increase N/A
    4. Round Steel Culverts 1% flow increase N/A

 29. Discharge water at exit design (ref. pages 9 - 11)

    1. GEM Culverts have a wider base, with discharge design capable of returning water to stream bed velocity, therefore limited erosion
    2. Round Culvert designs
    3. Box Concrete Culvert designs

30. Reducing high energy water flow at exit on a 8' installation.

    1. GEM Culverts – energy dissipated in approximately 18’ from exit (simulation and field tested.)
    2. Round culvert – energy dissipated in approximately 36’ from exit
    3. Box Concrete Culvert – energy dissipated in approximately 60’ plus                                                                       

31. Rotational effect on various culvert shapes.

  1. GEM Culverts – Rotational effect is not possible in this type of culvert.
  2. Round Culvert – Results are minimal, but disturbance of compaction occurs.
  3. Box Concrete Culvert – Effect on box culvert on open base would be substantial. Effect on enclosed box culvert would be much less, but still can occur.
  1. Culvert Failures at joints, clamps or seals due to compaction failure and movement of soils.
  1. GEM Culvert uses a unique seal that lasts the life time of the concrete with superior compaction. GEM culvert with all components locked together with stress relief as well as superior compaction due to design.
  2. Round Steel culvert has the culvert and clamps fail in 20% to 40% of the longevity of the structural concrete. Impossible to completely compact bottom or haunches.
  3. Concrete Box Culvert - The seals fail due to compaction failure or seal failure usually less then 25 years.
  4. Concrete round Culvert- the seals fail due to compaction failure because of uneven compaction at the haunches, seals often lasts less then 15 years.

33.Sediment problem.

1. GEM Culvert, high speed water cleans culvert refer to photograph 11

2. Box Culvert

3. Concrete round culvert

4. Steel Culvert (Corrugation retains sediment beginning at bottom of curvature)


1. GEM culvert attained first place in 32 of 33 categories, and second in weight category.  

2. Items 2, 3, and 22 result in less time with an open stream bed resulting in increased Public Safety. GEM Technology available to reduce installation times.

3. Items 18 and 19 indicate fewer culvert replacements over time resulting in cost savings.

4. Lower transportation costs to site, when compared to other concrete culverts (ref. Item 2, 3, and 10)

5. Items 29 and 30 indicate reduced environmental impact (geomorphic and erosion)

6. GEM’S ability to dissipate energy, within the right of way lowers downstream liability of “off right of way” erosion compared to other designs. Other designs require expensive land purchase or liability agreements.

Complete manual available upon request.  

Field Tests to Confirm Culvert Performance and Computer simulation

The Compression test that was completed on the GEM Culvert was 1000 pounds per lineal inch on the free standing GEM Culvert.  This is no where near the maximum for this force in a compression test with this flow capacity validates computer simulation. Testing at spring runoff or high flow in field trials validate computer simulation results for flows and erosion impact. The field test validate the computer simulation results therefore all of the Autodesk software simulation can be considered to be accurate.

Photographs of the GEM 6 foot triangular culvert prototype installation in MD#133 in northern Alberta, Canada located in a area to compare flows with a 8 foot 2400 mm galvanized round culvert using the same stream for fair and equitable study. 

This prototype GEM 6 foot triangular culvert was installed in 2019, in  cooperation between MD#133 and GEM Holdings Ltd. including data collection. 


Packer running no closer then 2 feet from structure, until surface compaction occurs at 1 foot above structure. No hand packers where used in this installation. 


Winter conditions (no ice as water has drained). The erosion control plates are designed to hold water and allow for freezing.


High flow and high velocity water. 


Stream exiting culvert and returning to normal flood flow.


Stream exiting culvert and returning to normal to high water flow.

Photographs 3,4,5 depicts exit flow of the GEM 6foot culvert at high flow using 77% of entrance capacity. This represents approximately 120 cubic feet per second of flow traveling through the 6 foot GEM Culvert.


The round 8 foot Culvert it is 2 feet down to the inlet water from the top therefore there is approximately 120 Cubic feet traveling through the round culvert. At full capacity the 8 foot culvert flows at 150 feet per second.  This validates the GEM Culvert flow claims. This engineered installation is located 1 mile down stream of the engineered GEM Culvert. The GEM 6 Foot and the 8 foot round or 2400 mm culverts have approximately the same flows at 120 cubic feet per second.


Low flow inlet water at GEM Culvert Entrance with no evidence of erosion. It can be assumed that the inlet water acceleration occurs on the entrance plate between the designed wing walls and inside the culvert.


Exit erosion control panels have controlled downstream erosion as no erosion is evident.

No evidence of erosion at low flow
No evidence of erosion at low flow.
There appears to be no erosion down stream of the GEM Culvert. It can now be assumed that the Autodesk simulation indicating the energy contributing to erosion occurs or is dissipated on the GEM exit plate and the erosion plates prior to exiting the road right-of-way. This is not possible with the old round and box technologies with this kind of stream flows. Photograph taken at low flow indicating no erosion at entrance. It can now be assumed that the water acceleration occurs on the concrete entrance plate between designed wing walls as well as in the culvert prior to exit.  
The low flow water indicates by even flow the culvert has remained level throughout installation, compaction, winter use and spring high flow runoff. (The highest in 20 years according to local land owners)
Photograph 11 depicts low flow inside culvert (2 inches). There is no evidence of sediment deposits. This would indicate the flow velocity in the culvert does not allow sediment to deposit and restrict flows as in a round culvert. This problem occurred at this site with previous round culvert installations.
These field tests validates the GEM Culvert computer simulation. By validating GEM computer simulation in strength and flows it can be assumed all of Autodesk's simulations are accurate.
Photo 12 depicts the culvert has been exposed to substaintial sediment and debris.
Photo number 13 depicts no impact from debris or sediment and the GEM Culvert has maintained its integrity in structure after 2 years of spring break-up and road use. This site indicates that the culvert will not be impacted by sediment as in round culverts. The GEM Culvert has many environmental benefits.
Photo number 14 depicts. The culvert that has had water conducted over three different years, one average year, one in 20 year flood year, and one normal year with drought conditions at time of photo. Located in a high silt and debris area, there is zero silt and debris in the culvert that was installed at 1.5 degree slope. This is the only culvert capable of this performance. After full flow has receded the culvert will flow at approximately 4.5 feet per second in a 3 feet per second creek flow.
Picture #15 This photograph depicts the culvert after four years of service and it is silt free. 

This photo depicts the GEM Culvert in the winter of February 2022.  The temperature during the day remains below -5°C and -20° to -30°C during the night.  The water in the entrance and the exit are frozen and water in the culvert is liquid.  It can be rationalized that the GEM Culvert will not require ice removal or steam cleaning as other culverts often do.  The GEM Culvert will attain full flow capability at the time of spring break-up.  This is not the case in other technologies that have a substantial portion frozen, reducing flow capability. 

This was an unexpected important quality as no inspections were conducted during low-temperature winter conditions previous to this photo.   This is the impact of the low heat conduction of concrete.   This is of benefit in Northern Permafrost installations (Alaska and Northern Canada).


No downstream erosion, no metamorphic damage and erosion control panels have retained pure water for wildlife to drink unlike competitors.



Wildlife benifits validated by showing dear tracks using GEM Culvert for safe passage under roadway.


No culvert deterioration or debris accumulation after 5 years of use.


No road way surface deflection, as would be evident in competitors installations.  

Alberta Transportation Canada Approval of GEM Culvert 
The GEM Culvert has met or exceeded the requirements of the Alberta Transportation Engineers in its required field trial. The GEM Culvert has now after 5 years of constant use and monitoring, no deterioration. This indicates approval for all Alberta Transportation use in the non-bridge culvert category which was a condition of the GEM prototype installation approval.

Wildlife benefits of the GEM Culvert are many.  One characteristic realized by the GEM team, which is significant, occurs after full flood flow or peak flow (Q-20).  Fish migration occurs after floodwaters have receded or after the water has drained from the farm and forest lands when silt and debris are limited.  The high flow from all culverts has lower velocity flows as occurs in the rivers and streams.  The GEM Culvert has a lower velocity than at high flow.  The GEM team noticed that the low flow in the GEM Culvert was maintained after the box and round culvert had ceased to flow or had limited flow.  The team also noticed that the low flow was being regulated and not only accelerated through the 6’ triangular GEM Culvert of approximately 15 cubic feet after the round and box culverts had ceased to flow.  GEM maintains that the low flow is relative to the 15 sq. ft. triangular entrance compared to the 40 sq. ft. round (50'³ x 80%) or the 48 sq. ft. box culvert (16' x 4')75%.  When the stream is flowing less than 3'/sec. the volume of flow is established by the entrance area relative to time.  This means that the box culvert with 48 sq. ft. entrance will stop flowing first; the 40 sq. ft. round culvert will stop flowing next and the 15 sq. ft. triangular culvert stopped flowing last as in the prototype installation.  As mentioned this is a significant benefit to fish and wildlife because the flow is prolonged for fish migration during dry times.  The GEM Culvert has a water containment basin that limits erosion, generally within the road right-of-way and provides a water reserve, that is replenished after each shower for wildlife benefit.


Project Assessment

  • Project Costing
  • Budget Estimating
  • Project Consulting

Site Survey

  • Site Surveying and Assessment

Engineering Designs & Services

  • Site Installation
  • Site Safety
  • Calculating Hydro Flows
  • Calculating Culvert Sizes
  • Stress & Dynamic Analysis on Models with Software
  • Fluid Flow Analysis Optimization with Software
  • Environmental Impacts 
  • Erosion Control
  • Addresses Permafrost Concerns

Environmental Assessment

  • No Wildlife Harm (Birds & Fish)
  • Limits or eliminates erosion or metamorphic impact as compared to other designs.


  • Site Installation
  • Transportation of Product to Site
  • Site Assembly