Blackmarsh Road Roundabout

CLIENT: City of St. John’s

YEAR: 2015

ROLE: Roundabout Design

CATEGORY: Roundabouts

Blackmarsh Road Roundabout

CLIENT: City of St. John’s

YEAR: 2015

ROLE: Roundabout Design

CATEGORY: Roundabouts

Past planning by the City of St. John’s with respect to the construction of the Team Gushue Highway has identified needed infrastructure investments at nearby intersections in order to help with traffic congestion and to provide a streamlined, efficient traffic network to accommodate this new piece of highway infrastructure in the City.

Not only must these types of intersections (adjacent to the highway) provide for safe, efficient movement of traffic, they must also be designed in a way that is user-friendly for pedestrians, drivers, cyclists, trucks and other road users. Further, this type of “gateway” intersection must work to promote economic development in this area of St. John’s by creating a sense of local identity and bringing more people to the area.

HTC investigated the option of a roundabout design and a signalized intersection for the Blackmarsh, Empire, Redmond intersection. In both cases, was to provide a prominent gateway feature for this area of St. John’s. The final design was selected to be a roundabout in order to give a safe, high-capacity intersection and will serve all users (vehicles, trucks, pedestrians, cyclists) in the best manner possible. The work is described below:

Design

  • Testing of the traffic performance of the intersection for current and projected traffic flows and future proofing consideration.
  • The selection of the final layout balanced and optimized the following parameters: Operations, safety, access management, geometry, aesthetics and Environment, costs and public feedback.
  • Costs not only considered capital costs considerations, but analyzed life cycle costing which included the following considerations: Construction costs, maintenance costs (electricity, snow clearing), collision costs and congestion costs (time loss, fuel consumption, emissions).
  • Intersection layout and geometric design, street grading and stormwater design, intersection/corridor lighting, visualization of the final appearance of the completed intersection in the form of renderings and computer-generated animations, signage and pavement marking design, production of tender documents (drawings and specifications).
  • The intersection was an operationally complex situation that did not take full advantage of its function as a major gateway into the West End or as a major access point from the Team Gushue Highway. This redevelopment project not only improved the safety of the intersection but will also introduce an aesthetic that welcomes citizens and residents into the West End along Captain Whalen Drive.

 

Unique Aspects:

  • One of the first roundabouts in the City of St. John’s

 

Project Challenges:

  • Complex geometry
  • Residential driveways close to the intersection
  • Significant Municipal services in the vicinity
  • Traffic control during construction