Prior to improvements constructed in 2007, the Armdale Rotary was a non-conforming traffic circle, located in the Armdale district of Halifax, Nova Scotia. The intersection receives vehicles from five different directions including traffic from the Halifax Peninsula, the Chebucto Peninsula, and along the isthmus of the Halifax Peninsula. It currently handles approximately 60,000 vehicles on weekdays. The historic intersection predates modern automobile traffic but was designed as the Armdale Rotary during the post-war period to handle 5,000-20,000 vehicles. In 2004, Halifax Regional Municipality (HRM) commenced a series of operational reviews aimed at improving safety and efficiency with modern roundabout operating characteristics. This paper documents the history of the operational changes leading up to the 2007 reconstruction; and, the study of deficiencies arising from ineffective geometry and incorrect lane configurations, particularly for a multi-lane and multi-leg roundabout. Methods used to resolve safety and capacity deficiencies represent an application of design principles that are rooted in U.K. practice, but transcend the current guidelines and analysis tools. Innovative overhead lane designation signs were also applied with success. The main accomplishment of this work, in terms of advancing roundabout design practice, is that the in-service improvements demonstrate the subtleties of the geometry/safety/capacity/marking relationships that were applied in the design development. After changes to priority rules and implementation of improvements in 2007, previous conflict patterns have virtually disappeared and queues have reduced substantially. Lane discipline and congestion relief is noticeable at the roundabout with the P.M. peak hour exhibiting the largest reduction in conflicts and congestion. For the covering abstract of this conference see ITRD number E220308.
Abstract