Harbourside Transportation Consultants HTC provided consulting design services to assist with the design of three roundabouts to be constructed with the Galway development in St. John’s. HTC’s scope of work was for preliminary and detailed design of the three roundabouts and the roadway between roundabouts ‘A’ and ‘B’.

The scope of work for the design included the following:

• HTC designed alignments, auxiliary lanes and section elements
  (pavement, profile, cross fall transitions and supporting infrastructure).
• Prepared drawings in Civil 3D for clearing limits, and daylight lines with
  the goal to minimize the clearing and property requirements.
• Specific attention was be paid to areas near streams, water crossings,
  wetlands, water transmission mains and developed areas.
• HTC designed the interchanges and alignments in accordance with
  NLDTW standards, and the TAC Geometric Design Guide for Canadian
  Roads.
• Develop and optimize the horizontal geometry of the roundabouts with
  respect to capacity, safety, construction costs and property impacts.
  Considerations that influence this optimization include vertical profile,
  sight distances, utility locations and property.
• Provide the horizontal geometry and curb layout for the roundabout to predesign in AutoCAD, using the UK Design
  standard (TD 16/07).
• Detailed design of the connector road and three roundabouts, at the Ruth Avenue interchange, labelled
  Roundabouts ‘B’ and ‘C’ and the roundabout in the commercial development, labelled Roundabout ‘A’.
• Roundabout signage and pavement marking drawing, including all roundabout guide signs and regulatory signs.
• Specify sight distances and landscaping restrictions (sight triangles), entry angles, and fastest path analysis for the
  roundabout in AutoCAD with diagrams for submission to NLDTW, Mount Pearl and St. John’s.
• Complete turning movement diagrams for the design vehicle, as specified by NLDTW.
• Contract drawings and tender quantities for the roads and roundabouts.
• Lighting layout drawing.
• Accommodation for pedestrian facilities.
• Location of Storm drainage inlets.
• Liaison with NLDTW, St. John’s and Mount Pearl.

Unique Aspects:

• Design of multi-lane roundabouts

Project Challenges:

• Multiple stakeholders, including the
  developer, 2 municipalities,
  Provincial Department of
  Transportation and municipal
  services consultant.
• Delivered design in an extremely
  accelerated design schedule.