Team Gushue Highway Interchange Study
Location: St. John’s, NL
Client: Newfoundland and Labrador Department of Transportation and Works (NLDTW)
Duration: 2019-2020
Key Personnel: Michael MacDonald, Kevin MacDonald, Mark Stuckless, Florence Allaire, Jim Hayward.
Project Description
Harbourside Transportation Consultants was retained by the NLDTW to complete a detailed traffic analysis to review the impact of recent and future development on the Team Gushue Highway and the existing Pitts Memorial Drive and Robert E. Howlett Memorial Drive interchange. The end goal was to develop alternatives for connecting these and ancillary roadways.
Harbourside Role
Harbourside Transportation consultants undertook a holistic approach to this project. Work began with a comprehensive review of past transportation planning documents, traffic studies and transportation planning models. This was followed by stakeholder consultations with adjacent municipalities to identify regional growth and development projections that could have an impact on the study area.
After assessing the current traffic operations at the study area, Harbourside developed three (3) travel demand forecasts with PTV Visum: redistribution of existing traffic with the completion of the Team Gushue Highway, a 5-year regional growth projection and a 15-year regional growth projection.
Harbourside also conducted the review of the initial design for the Team Gushue Highway alignment and connection to Pitts Memorial Drive and Robert E. Howlett Memorial Drive. Three concepts were then developed and tested for connection alternatives that maintained the original alignment and connection location but provided different configurations for the connection. This was followed by the development of seven (7) conceptual options for the complete reconfiguration of the Team Gushue Highway connection area. The options considered included at-grade roundabout or signalized corridors with diamond interchange configuration, cloverleaf interchange, diverging diamond interchange, interchange with flyover ramps, and the complete relocation of the Team Gushue Highway connection.
A multi-criteria evaluation was used to determine the best options amongst the initial seven conceptual plans. Of these concepts, three (3) preferred options were chosen for their functional design. A singular preferred option was then selected from the three, after another round of multi-criteria evaluation. This evaluation criteria considered capacity, safety, construction sequence and construction impacts, land/property acquisition, access to private properties, agricultural impacts and ability to accommodate farming operations, environmental impacts, drainage and stormwater requirements, structures requirements, operational considerations and total project development costs.
Finally, a microsimulation of preferred option with PTV Vissim was conducted to provide proof of concept.
Unique Challenges
The scope of this project required consideration from many different angles. Multiple concepts had to be tested against each other to find the best functional design amidst many possible alternatives. Extensive study and review were required, ultimately landing on the optimal choice.
Social Impact
The completion of the Team Gushue Highway will mark an important milestone in connecting the city of St. John’s. Although construction has been underway for some time, the project is entering its final stages. This will allow for greater accessibility throughout the city, and the region as a whole.