Reversible Lane Control Systems

Calgary, AB

To avoid the need for costly or controversial road widening projects, the team of ISL and PBA Engineering were engaged by the City of Calgary in 2008 to plan, design, build and commission an automated control system for innovative lane reversals for Memorial Drive and the 5 Avenue Connector on Bow Trail. This was the first such system implemented in Calgary since the 1970s.

Automated Mechanisms

This project introduced new traffic control devices, including signals, traffic-control gates, dual-state sign boards, variable message prism signs and traffic-monitoring cameras. The reversible lane control systems are also the first to be integrated with the City’s Traffic Management Centre (TMC), providing a flexible system that safely and efficiently transitions the reversals from the central control centre using a fibre-optic network, central server and software integration.

Traffic Management Centre

The automated systems provide video monitoring and remote-contral capability to the TMC operators. Nine pan-tilt-zoom cameras (7 new, 2 existing) were installed for the projects, allowing operators to visually verify that lanes are clear prior to opening a lane to opposing traffic. All field devices are monitored and operated through 5 distributed controllers and two remote I/O cabinets. Communications are relayed using a fibre-optic-based Ethernet and a 802.11G wireless network.

Traffic Improvements

The project has significantly increased traffic capacity around Calgary’s downtown core by more effectively using existing road infrastructure. It has also reduced peak hour congestion, saving affected commuters up to 11 minutes of delay for each trip, or nearly 60,000 hours annually. A marked reduction in community shortcutting on parallel roads has improved quality of life for residents of established communities around the downtown core.

Project Completion

Completed in March 2010, the reversible lane control systems are now a permanent feature of Calgary’s weekday commute. This project won a 2011 Consulting Engineers of Alberta Award of Merit for Studies, Software and Special Services.

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G37 Interchange – Stage 1 Detour

Calgary, AB

ISL and CH2M HILL partnered as lead consultants to the City of Calgary for functional planning, design and construction of a grade separated interchange at Glenmore Trail and 37 Street SW that would eventually serve as the detour for Alberta Transportation’s Southwest Ring Road (SWRR) construction.

Five Months

The goal of opening Glenmore Trail to free flow traffic and removing commuter congestion for over 70,000 vehicles per day has been a publicly stated objective of the City for well over a decade — this project solved the long-standing issue in only five months.

Recycled and Reused

Key innovations included building Calgary’s first roundabout interchange and designing a recyclable overpass bridge with a pre-cast superstructure built in a record-setting 23 days. ISL’s sustainability decisions included reusing existing girders and not having piles for the abutments, making the panels fully reusable and enabling easier dismantling of the temporary overpass bridge.

Award Winner

The G37 Interchange won a 2011 Consulting Engineers of Alberta Award of Excellence for Project Management.

"This team did an outstanding job of documenting how it developed and applied best practices in project management strategies and processes to successfully meet the complex challenges and timelines. A textbook example of how such projects should be done!"
— CEA Showcase Award judge's comment
(Alberta Innovators magazine, spring 2011)

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Macleod Trail and 162 Avenue Diverging Diamond Interchange

Calgary, AB

An historic event, the decision to build the first DDI in Canada was made for a variety of reasons including increased safety and capacity, and ease of construction. Land had been reserved in the area decades ago for a partial cloverleaf interchange but it did not stand the test of time and new thinking was required. ISL had evaluated DDIs at a number of locations in Calgary before but it was never the right fit until 162 Avenue.

The Design

The design promotes a free flow of traffic both below and above the new overpass. Unlike a standard diamond interchange, traffic is divided based on direction – all left-hand traffic is funneled to the left side of the road and can turn onto the major thoroughfare without waiting at a stop light or worrying about crossing oncoming traffic.

Benefits During Construction Sequencing

The construction sequencing allowed for the project to remove the traffic signal from Macleod Trail in October 2016, tremendously improving traffic flows nearly a year before the interchange was finished.

Calgary’s Unique Context

The team thoroughly surveyed current practices in DDI implementation in the United States and paid careful attention to getting every detail right for Calgary’s unique context including driver behaviour and climatic conditions.


This major milestone was achieved because of the close collaboration between ISL, The City of Calgary and Graham Infrastructure. The City and their senior leadership team in particular were instrumental, providing expertise across many departments and motivating the team by providing strong support to successfully implement this new and innovative solution.

Award Winning Interchange

The DDI received a 2018 Minister's Award for Transportation Innovation in Construction as well as a 2018 Consulting Engineers of Alberta (CEA) Award of Excellence in Transportation Infrastructure - Roads, interchanges, airports, mass transit and ports and a 2018 CEA Award of Merit for Project Management.

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Northwest Anthony Henday Drive

Edmonton, AB

Alberta Transportation retained ISL as the Owner’s Engineer for the Design, Build, Finance and Operate (DBFO) process for Edmonton’s Northwest Anthony Henday Drive. This major project connects the northwestern section of the ring road around Edmonton.

Project Elements

This stretch of the Henday includes 21 km of freeway, 29 bridges in 8 interchanges including 2 full systems interchanges and 2 grade-separated rail crossings, and 9 stormwater ponds.

Owner's Engineer

ISL advised Alberta Transportation on all design and construction aspects including roadways, bridge and wall structures, drainage, signage, pavement marking, traffic accommodation strategies and environmental monitoring. ISL's services included reviewing and auditing the engineering detailed designs, assisting in the ongoing management of the contract until construction completion, and construction monitoring and auditing.

Vast Databases

Some of the challenges included utility conflicts, traffic accommodation to keep traffic flowing during construction, and efficient management and tracking of vast amounts of data. The ISL team developed a rigorous system for reviewing and auditing the engineering detailed designs as they came into the office to ensure each met with Alberta Transportation’s requirements. We also set up a comprehensive database to manage and track over 5500 records to timely completion.

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Flanders Avenue Interchange

Calgary, AB

The Flanders Avenue Interchange on Crowchild Trail stands at the crossroads of Calgary’s history, serving as the front entrance to the former Currie Barracks at Canadian Forces Base Calgary since it opened in the mid-20th century. Following closure of the base in the late 1990s, the surrounding lands have been redeveloped into some of Calgary’s most innovative and sought-after neighbourhoods.

Innovative Design

To improve access and comfort for all modes of transportation, ISL was engaged to lead the planning for upgrades to the Flanders Avenue Interchange. Through a comprehensive technical evaluation and community engagement process, ISL developed an innovative interchange design that fit the urban context, opened up new access opportunities and accommodated future growth in the surrounding area.

A First for Alberta

As Alberta’s first interchange with multi-lane roundabouts, it uses a unique series of three roundabouts to connect seven streets through a single overpass location.


The interchange was delivered using a unique Design-Build procurement model, with joint funding by Canada Lands Company and The City of Calgary.

Cooperative Approach

ISL acted as Owner’s Engineer for the D-B process, responsible for preparation of procurement documents and administration of the pursuit process that ultimately awarded the work to a team led by Westpro Infrastructure. ISL collaborated with the Engineer of Record through design and construction of the interchange to bring ISL’s functional design to life and provided audit service throughout the construction process. The cooperative approach of the consulting team exemplifies industry collaboration and delivered excellence in transportation infrastructure and project management.

Official Opening

The revitalized interchange officially opened to traffic on October 31, 2016, forming a gateway into the emerging communities and enhancing mobility for generations of Calgarians.

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