Alberta Transportation (AT) initiated this VSL scoping study to outline specific requirements for implementation on the QEII corridor between Calgary and Edmonton.

Client: Alberta Transportation

Location: Alberta

Project Type: Transportation

About This Project

ISL and PBX Engineering partnered to deliver this study, where we integrated our transportation planning, GIS, community engagement, and PBX’s electrical engineering and ITS experience. This study is a scoping study, if implemented, the infrastructure capital cost could be as high as 80 million. This is a detailed scoping study for the VSL technology, which would be the first in Alberta, if built.

As Variable Speed Limit (VSL) system has been found to reduce traffic collisions due to weather or traffic conditions by up to 25%, Alberta Transportation (AT) initiated this VSL scoping study to outline specific requirements for a VSL implementation on the Highway 2 corridor between Calgary and Edmonton. This VSL system will be able to dynamically modify speed limits in real-time based on various factors, such as temporary highway conditions, adverse weather conditions, or traffic congestion.

A detailed corridor review of traffic volumes, collision records, and road conditions was conducted, which recommended four high-priority segments, including three urban segments near urban centres (Edmonton, Red Deer, and Calgary) and one rural segment (Innisfail–Olds). Benefit cost analyses identified the rural segment with the highest benefit cost ratio of 3.5 and the Edmonton–Leduc segment as the urban segment with the highest benefit cost ratio of 1.5.


A legislative review was conducted to understand potential legislative and regulatory changes required to implement an enforceable VSL. Stakeholder meetings were held with representatives from AT Legislative Services and the RCMP, and it is concluded that the current Alberta legislation and AT regulations and policies may need to be amended to support permanent VSL implementation, but no changes on legislation are required for a VSL pilot.

Concept of operations was recommended with sign placement and spacing guidelines established. The proposed VSL system consists of several ITS components, including VSL software and signage, Gateway Dynamic Message Signs, Dynamic Message Signs, CCTV cameras, pavement condition and temperature sensors, present weather detectors, and traffic and visibility sensors.

The VSL presents the recommended posted speeds based on the lowest speeds recommended by two automated response subsystems: the traffic responsive subsystem considers aggregated traffic speed and density, and the road weather subsystem considers aggregated pavement temperature, pavement condition, visibility, wind and weather data. 

Stakeholder consultations were conducted with representatives from various AT departments to define the needs and concerns of these stakeholders. System actors, use cases, and functional requirements were developed, and a corridor key plan was presented in an innovative format via Google Earth, which allows instant viewing and revision of how the proposed VSL will look on the ground.

Integrated Expertise

  • Transportation Engineering
  • Community Engagement
  • Geomatics
  • Supporting Services

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