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HRM Roundabouts

History of Roundabouts

Historic photo of Armdale RotaryIn the early 20th century, numerous traffic circle junctions were constructed in the United States and Canada which allow entry at relatively high speeds and require entering drivers to weave with exiting and circulating traffic. Although the United States was home to the first one-way rotary system in the world (implemented around New York City's Columbus Circle in 1904), traffic circles had fallen out of favor in this country by the 1950s. Older traffic circles, located primarily in the northeastern states and Canada, encountered serious operational and safety problems, including the tendency to lock up at higher volumes

Modern Roundabouts around the world began to emerge when British engineers re-engineered the circular intersection during the mid-1960s. Unlike traffic circles, traffic approaching roundabouts is normally required to give priority to circulating and exiting traffic and to eliminate much of the driver confusion associated with traffic circles and waiting queues associated with junctions that have traffic lights. Roughly the same size as signalized intersections with the same capacity, roundabouts also are significantly smaller in diameter than most traffic circles, separate incoming and outgoing traffic with pedestrian islands to encourage slower and safer speeds

The modern roundabout, although following different design principles from those of the old circles, has been notably less popular in the United States and Canada than abroad, in part because of this country's experience with the traffic circles and rotaries built in the first half of the 20th century. Since 1990 there has been an emergence of the modern roundabout in some parts of the United States and Canada. The strong interest expressed in this type of intersection in recent years is partially due to its success in several countries in Europe and in Australia, where the modern roundabout has changed the practice of intersection design.

History of Roundabouts within the

Halifax Regional Municipality

The concept of circular intersections is not new for the Halifax Regional Municipality (HRM), although roundabouts with yield on entry, smaller size and deflected through paths is.  Rotaries date back in the HRM to the 1950’s, the Micmac rotary in Dartmouth and the Armdale rotary in the Halifax are the two most often cited examples of traditional circular intersections in the HRM.  The Micmac Rotary was replaced with a Parclo (named after it's resemblance to a partial clover leaf) interchange in the late 1980’s. The Armdale Rotary was re-designed to more closely conform to modern roundabout geometry in 2007.

Micmac Rotary

The Micmac Rotary was owned and operated by the Province of Nova Scotia within the former City of Dartmouth (now part of HRM). It was located at the intersection of Highway 111 with Route 318 (Braemar Drive/Waverley Road) and Trunk 7 (Main Street/Prince Albert Road/Graham’s Grove). The Rotary was named after nearby Lake Micmac, which was partially in-filled to accommodate it. The Micmac Rotary was notorious for rush hour congestion, even resulting in the recording of a song entitled “Micmac Rotary Blues". The rotary was removed during the redesign of the intersection in the early 1990s and replaced by the "Micmac Parclo”, which consists of a series of overpasses and controlled access lanes.

Micmac Parclo

Armdale Rotary

The intersection predates modern automobile traffic and was redesigned as the Armdale Rotary in 1955 to handle 5,000 to 20,000 vehicles per day. The Armdale Rotary receives vehicles from five different directions: Chebucto Road, Quinpool Road, Herring Cove Road, St. Margaret’s Bay Road, and Joseph Howe Drive. In October 2005, the Province of Nova Scotia amended the Motor Vehicle Act which described how a vehicle was to traverse a rotary or roundabout. It stated that all entering vehicles must yield to vehicles circulating in the rotary or roundabout. The amended legislation prompted HRM to install “Yield” signs on both Herring Cove Road and Chebucto Road approaches to the Rotary (the two approaches that were not signalized) to conform to the new legislation. The yield signs were also supplemented with warning “Yield Ahead” signs. In 2007, carrying over 55,000 vehicles per day, the geometry of the Armdale Rotary was modified to more resemble a modern roundabout. These geometric changes included realigning the entry/exits of five approaches in order to slow vehicles down, updating signs, pavement markings, and lighting, as well as the addition of a multi-use trail around the perimeter of the circle.