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Consideration of a Diverging Diamond Interchange in Saskatchewan


The TransCanada corridor (Highway No. 1) east of the City of Regina, Saskatchewan has been
the recent focus of several planning studies to address the ever increasing growth in traffic as
development and communities expand. As this traffic has increased, the Ministry of Highways
and Infrastructure identified the need to address safety concerns at the existing at-grade
intersections. The first step was to complete the Highway 1 East Functional Planning Study (1)
which identified future access improvements. This study was subsequently followed by the
functional interchange designs being approved for Highway 1 and Highway 46 at Balgonie, and
Highway 1 and Highway 48 at White City. The functional interchange design for the Pilot Butte
access completes the rural interchange planning for Highway 1 from Regina to Balgonie.
This paper will present functional design considerations that led to the evaluation and selection
of the preferred interchange option for the Pilot Butte access; a Diverging Diamond Interchange.
Through consultation with many developers and local municipalities, traffic volume forecasts for
future design horizons were established. Determination of these volumes considered the timing
of possible developments and the origins and destinations of associated trips. As such, two
predominant movements became apparent; the eastbound to northbound left turn and the
northbound to westbound left turn. Based on a need to address these predominant movements,
several conceptual interchange options were established with the Diverging Diamond
Interchange expected to offer the greatest benefit from a safety, operational and cost
The design and construction of a Diverging Diamond Interchange at the Pilot Butte access is
believed to be first such configuration to be considered within Canada. During the planning
study, which reviewed several interchange options, local media coverage has created some
excitement amongst the road safety and engineering communities, as well as local
stakeholders. This could be a landmark project for the region, local communities and provincial
government. The intent of this paper will be to present some of the design considerations made
during the planning component of this work as well as feedback received from those facing the
prospect of using this new innovative interchange design.
The possibility to stage the construction of this interchange has been reviewed. It is recognized
that the ultimate lane configuration will not be required on opening day since development will
still be at various stages. The expected traffic volumes that would need to be accommodated
upon completion of the interchange assume completion in 2015 with the interchange design
horizon established as 2045.

Conference Paper Details

Session title:
Geometric Design - Learning from the Past
Steel, P.
Schmidt, T.
Miller, B.L.
Geometric design