Bridge deck finishing demands precision, efficiency, and equipment that can adapt to varying project requirements. The Graham Group Ltd., a Calgary-based contractor with nearly a century of construction experience, demonstrated these principles on a challenging twin-bridge project along Highway 2 near Airdrie, Alberta. Using a GOMACO C-450 finisher equipped with innovative transitional framework, the team successfully completed bridge decks spanning 104 feet while achieving significant weight savings and faster assembly times. Understanding how different Types of Bridges influence construction methods helps contractors select the right equipment and techniques for each unique project scenario.
The Graham Group and Its Bridge Building Heritage
Company Background and Evolution
Graham Group Ltd. traces its roots to Moose Jaw, Saskatchewan, where it began operations as a general contractor in 1926. Now based in Calgary, the company has grown into a diversified construction and construction management enterprise while keeping bridge construction as a core competency. The firm began building bridges approximately 50 years after its founding and has continuously refined its approach to bridge deck construction ever since.
The decision to invest in new finishing equipment came after company leadership sent David Impey, Director of Engineering, to World of Concrete to research the latest bridge technologies. This systematic approach ensured the investment would serve current and future project needs.
Equipment Selection Process
The research at World of Concrete led Graham to the GOMACO booth, where Impey connected with Bob Coats, Cylinder Finishers Product Manager. This partnership produced a GOMACO C-450 with transitional framework, designed to address wide bridge deck finishing while maintaining versatility for narrower spans.
- David Impey researched at World of Concrete in 2010
- GOMACO collaborated on custom C-450 configuration
- Transitional framework developed for Graham’s requirements
- Machine deployed immediately on Highway 2 project
Transitional Framework Technology and Design Innovations
How Transitional Framework Works
The transitional framework represents a significant departure from conventional wide-width finishing equipment. Traditional wide-span finishers require an overhead truss system to maintain rigidity across extended widths, adding substantial weight and assembly time. The transitional framework eliminates this overhead truss by using transition sections connecting the C-450’s standard 24-inch (610 mm) framework to the 42-inch (1067 mm) framework used on the larger C-750 finisher. The design spans widths up to 104 feet (31.7 m) while sections are pin-connected and cross arms bolted, dramatically reducing assembly time.
Weight Savings and Performance Benefits
One of the most significant advantages of the transitional framework is its weight reduction. According to Bob Coats at GOMACO, the transitional framework is approximately eight pounds per foot (11.9 kg/m) lighter than a comparable machine with an overhead truss. For Graham’s machine spanning 104 feet, this translates to a weight savings of roughly 832 pounds (377 kg).
| Parameter | Standard Overhead Truss | Transitional Framework | Improvement |
|---|---|---|---|
| Weight per foot | Baseline | 8 lb/ft lighter | 11.9 kg/m savings |
| Total weight at 104 ft span | Baseline | 832 lb lighter | 377 kg savings |
| Assembly time | Extended | Pin-and-bolt connections | Faster setup |
| Overhead truss | Required | Eliminated | Simplified logistics |
| Width versatility | Fixed wide setup | Removable sections | Dual-mode operation |
The weight savings also reduce the load on overhang brackets and support rails, which is important when structural loading must be carefully managed. Graham further distributed the machine’s weight by utilizing the optional third wheel assist on the C-450’s standard bogies. This modification adds two single-wheel idler bogies attached to the spreader beam on each side, spreading the load and reducing wheel pressure on overhang brackets. This modification can be applied to any C-450 or C-750 finisher.
Versatility Across Project Scales
A key design feature of the transitional framework is its adaptability. The transition sections can be removed entirely, allowing the C-450 to operate at smaller widths using its standard 24-inch (610 mm) framework. This gives contractors two finishers in one machine capable of handling both wide bridge decks and narrower structures. The transitional framework can be specified on new C-450 orders or retrofitted to existing machines.
Graham has already taken advantage of this versatility. After completing the wide twin bridges on Highway 2, the company moved the C-450 to other projects with narrower bridge decks. Kish noted that the team simply leaves the transition sections out and uses the standard 24-inch framework. For more on structural bridge components, see Plate Girder Bridges and their design considerations.
Highway 2 Bridge Deck Construction: Project Execution
Project Specifications and Preparation
The Highway 2 project near Airdrie, just north of Calgary, involved constructing twin side-by-side bridge decks. Each deck measured approximately 20,000 square feet (1,858 square meters) with a thickness of nine inches (229 mm). The concrete volume required for each deck was 620 cubic yards (474 cubic meters). Both decks featured a 4-inch (102 mm) crown to facilitate proper drainage.
Before concrete placement could begin, the team conducted dry runs with bridge inspectors on site. These inspections verified that the deck would receive proper concrete coverage and meet all specification requirements. Only after inspectors signed off could finishing operations commence.
Concrete Mix Design and Placement
Bridge deck specifications in Alberta require a concrete mix design that includes silica fume. This additive creates high-strength concrete, but it also produces a sticky texture that presents finishing challenges. Graham addressed this by equipping their C-450 with a heavy-duty, externally vibrated, double-cylinder undercarriage with five-foot (1.5 m) long cylinders. The external vibration helped overcome the stickiness of the silica fume concrete and produced a smoother finished driving surface.
- Silica fume concrete mix required by Alberta bridge specifications
- High strength achieved but sticky texture creates finishing difficulty
- External vibration system helps manage concrete stickiness
- Double-cylinder undercarriage with 5 ft long cylinders specified
- Slump maintained around 3 inches (76 mm) for easier placement
- Concrete pump used for deck placement
Concrete was placed on each deck using a concrete pump, with slump maintained at approximately three inches (76 mm) to facilitate placement and finishing. The C-450 was set on a skew to match the bridge geometry, and each bridge deck was completed over two days. Each daily pour covered approximately 10,000 square feet (929 square meters) and took between five and six hours to complete.
The Finishing Process
Once concrete was placed, the GOMACO C-450’s double-drum system moved across the deck, consolidating and finishing the surface. GOMACO service representatives were on hand during each pour to assist with machine setup and operation. Doug Kish shared a critical finishing adjustment that made a significant difference in final surface quality: setting the rear drum approximately 0.125 inch (3 mm) higher than the front drum. This adjustment proved essential for achieving the desired finish on the silica fume concrete mix.
Curing and Quality Control
After finishing, each newly placed deck section was covered with burlap and kept continuously wet using a spray-mist system for seven days. This extended wet curing period is essential for silica fume concrete to develop its designed strength and durability characteristics. Proper curing prevents plastic shrinkage cracking and ensures the long-term performance of the bridge deck.
The completed bridges serve approximately 30,000 vehicles per day, making surface quality and durability paramount. For related approaches to bridge and culvert construction, see Everything You Need to Know About Construction of Culverts and Minor Bridges Siting and Investigation of Catchment Area.
Training and Workforce Development for Bridge Deck Finishing
GOMACO University Training
Graham invested heavily in workforce training to ensure their team could maximize the potential of the new C-450 finisher. The company sent 12 employees to GOMACO University in Ida Grove, Iowa, for a week-long C-450 training class. Personnel attending ranged from laborers and equipment operators to superintendents and equipment managers, ensuring knowledge was distributed across all levels.
- 12 Graham employees attended GOMACO University training
- Week-long C-450 class covered assembly, operation, and maintenance
- Attendees included laborers, superintendents, and equipment managers
- Training addressed current and future project configurations
Kish reported that everyone benefited substantially from the training. The team learned what questions to ask when ordering equipment and how to configure the finisher for different job scenarios. The workforce became comfortable with the machine’s capabilities and setup requirements.
On-Site Support and Knowledge Transfer
In addition to formal training, Graham utilized on-site support from GOMACO service representatives during the bridge pours. This hands-on assistance translated classroom knowledge into practical field techniques, such as the rear drum height adjustment. The result was a workforce capable of maintaining production flow while achieving high-quality finishes on demanding bridge deck specifications.
Lessons for Bridge Construction Contractors
The Graham Group’s experience on the Calgary Highway 2 bridge project offers several valuable lessons for contractors. For additional guidance on precision construction transitions, refer to Calculating and Splitting Compound Miters Stair Skirtboard to Baseboard Transitions for techniques that apply across construction disciplines.
- Equipment selection driven by project requirements. Graham’s collaboration with GOMACO produced a machine tailored to their specific bridge deck challenges.
- Weight-saving transitional framework reduces structural loading and simplifies logistics on wide-span decks over 80 feet.
- Operator training at every level ensures equipment investments deliver maximum return through proper setup and maintenance.
- On-site manufacturer support during initial pours accelerates the learning curve for challenging mix designs.
- Proper drum setup with 0.125-inch rear-front height differential significantly improves final surface quality.
- Extended wet curing for seven days is essential for silica fume concrete bridge decks to achieve design strength.
Graham successfully completed the twin bridge decks on Highway 2 near Airdrie and has since moved the C-450 to other projects. The machine’s versatility allows it to handle both wide and narrow bridge decks, making it a valuable long-term investment. Kish summarized the project’s success by noting that the key challenge in any bridge deck pour is maintaining flow keeping concrete moving, workers productive, and the finisher finishing. The C-450 with its double-drum system and transitional framework proved to be the right tool for meeting that challenge on the Calgary bridges.