McKnight Boulevard Pedestrian Overpass

Calgary, AB

Located near 44 Street in northeast Calgary, a pedestrian overpass was needed to allow pedestrians to safely reach a school and a commercial district on either side of the busy, multi-lane McKnight Boulevard.

Project Services

ISL provided preliminary engineering, detailed design and construction administration for a twin girder pedestrian bridge, as well as the associated regional pathway extensions, utility diversions and drainage and landscape elements.

Slender Design

To cross 55 metres of roadway with a depth-to-span ratio of greater than 20, ISL configured the union of two steel plate girders with a maximum depth of 2.4 metres, thereby exceeding the design criteria for a slender bridge profile.

Overnight Installation

To minimize traffic disruptions on the busy McKnight Boulevard, it was decided to erect the twin bridge girders in just one night. Carefully planned and executed, temporary traffic control and lighting allowed both the girders and the precast decking units to be installed successfully with minimal disturbances.

Winter Conditions

To stay on schedule, much of the abutment concrete pours and bridge construction took place during harsh winter conditions. Special portable industrial heaters and insulated tarpaulins protected the freshly poured concrete from the cold weather.

Project Completion

The McKnight Boulevard Pedestrian Overpass opened to the public in September 2009.

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100 Avenue Bridge Rehabilitation

Grande Prairie, AB

The City of Grande Prairie selected ISL for this bridge rehabiliation project, which involved structural assessment and recommendation of rehabilitation options, followed by design, tendering and construction administration for the selected option.

State of Disrepair

Built in 1958 with only small fixes thereafter, the 100 Avenue Bridge was in a state of disrepair with reinforcing bar corrosion and numerous spalls of concrete along the deck curb. Bridge expansion joints were buried under six inches of Asphalt Concrete Pavement (ACP).

Rehabilitation Program

Inspections and assessments led ISL to recommend replacing the 39.5-metre long deck and rebuilding the wing wall, guard rail, abutments, bearings and approach slabs. Construction staging enabled two lanes of traffic to remain open for most of the construction, even though the work was extensive. A new High Performance Concrete (HPC) topping slab will increase the deck's durability and service life.

Girder Reuse

Analysis showed that the existing girders complied with bridge code loading, allowing ISL to develop a plan for girder reuse by rehabilitating their corroded ends. Construction efficiencies were maximized by lifting the girders and rehabilitating them off their supports, which enabled access to the abutment/piers for its rehabilitation at the same time. These measures resulted in substantial time and capital cost savings for the City.

Rehab Benefits

With the completion of these rehabilitations in December 2014, the service life of the bridge has been extended by 50 years or more.

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32 Street Crossing

Okotoks, AB

This project was the largest infrastructure project ever undertaken by Okotoks and was designed and built within one year to satisfy tight timelines set by the federal Infrastructure Stimulus Fund.

Vital Connection

This project involved constructing 1.4 kilometres of new arterial roadway including regional pathways, two bridges over the CPR track and Sheep River and a major river diversion within the flood plain. The project provides the only local route that will remain passable when trains cross or in major flood events, significantly improving network capacity for all modes of transportation.

River Relocation

ISL led a multi-disciplinary consulting team that included Golder Associates, who contributed significantly in hydraulics, flood management and biophysical science. A key innovation of the project was the 750 metre relocation of the Sheep River, returning the river to a course it had historically followed from the 1950s to the 1970s. This had numerous benefits, including mitigating the risk of flood damage on downstream lands, reducing bank erosion and allowing the new bridge to be constructed efficiently over dry land.

Environmental Stewardship

As the largest recorded diversion of a meandering alluvial mountain river, the project required careful design and extension of the current state of technical knowledge. Environmental monitoring and mitigation included extensive on-site fish habitat compensation measures, and an active relocation program that helped more than 11,000 fish migrate to the new river channel. All impacted areas within the river valley have also been completely re-naturalized, leaving Okotoks a lasting legacy of sustainable transportation design.

Award Winner

This project won two Consulting Engineers of Alberta awards: an Award of Excellence for Water Resources and Energy Production and an Award of Merit for Transportation Infrastructure.

"A multi-faceted project that has shown very high results in key elements of technical excellence, value, innovation and environmental protection. An impressive project of significant benefit to the Town of Okotoks."
— CEA Showcase Award judges' comments, Alberta Innovators magazine, Spring 2011

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Kingswood Pedestrian Bridge

Brackendale, BC

In fall 2009, ISL was commissioned to prepare a conceptual and detailed design of the 200-metre Kingswood Pedestrian Bridge across the new Sea to Sky Highway 99 near the Township of Brackendale in the District of Squamish, British Columbia.

Improved Safety

The new highway had virtually disconnected pedestrian crossing and access to the nearby school and residential areas in this section of the town. The bridge was proposed as a safety measure to accommodate pedestrian, cyclist and wheelchair traffic across the highway.

Recycled and Reused

ISL elected to re-use existing precast pre-stressed concrete flanged box and Double T beam members, which had been in storage from the dismantling of the Centennial Way Pedestrian Bridge Overpass. Modifying the design to use these superstructure beams helped reduce the capital cost of the bridge by 25 percent while providing a more sustainable solution.

Environmental Care

The bridge was designed and constructed to minimize environmental impacts on the nearby creek and a protected pond. A new culvert was installed to replace a dented and overgrown culvert on site.

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Highway 66 Elbow River Bridge Repairs

Near the Hamlet of Bragg Creek, AB

The bridge over the Elbow River bore a major onslaught of the flood waters from the June 2013 flood in southern Alberta. The force of the flood gouged not only a new path for the river, increasing its width from 180 m2 to 208 m2, but also sheared off nearly 25 m of earth behind the bridge. The resulting bridge debris was 15 m deep and 30 m wide, effectively cutting off all access to the Kananaskis Region.

Aggressive Timeline

ISL provided consulting expertise on all project phases for emergency bridge repairs and to restore connection to the Kananaskis Region. We were given an aggressive three month timeline that required an innovative design and construction schedule. Pier, girder and new bridge span construction were carefully orchestrated to ensure there would be limited scheduling construction conflicts.

A New Path

The flood waters created a new path for the Elbow River, which required numerous design decisions regarding how to repair the bridge. Rather than re-direct the river to its normal course, ISL designed the piers and abutments to accommodate the new river flow and strategically located the new abutment behind upstream rock outcropping to protect the bridge and ensure it could withstand a future flood of similar intensity.

Facing Winter

As winter approached, the team had to make a critical decision regarding the design of the bridge deck. ISL designed the bridge girders to take both a concrete deck slab and a temporary wood deck that could handle traffic loads until the weather was conducive to constructing a concrete deck.

Project Completion

In three months, ISL was able to complete repairs and on December 20, 2013 the Elbow River Bridge was opened.

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