TRANSPORTATION STUDY

4.3 Roundabout Alternative
The roundabout is becoming an increasingly popular alternative to the conventional intersection with
one already successful implementation within the Town (Poplar Sideroad with High Street) and others
soon to be opened (Poplar Sideroad with Highway 26 New). Although considered unconventional due
to their lack of presence in Canada, the roundabout can be a very efficient intersection configuration
and thus is being considered more seriously when evaluating intersection improvement options. There
are two main advantages of a roundabout:
• Safety - Several studies show that the number of incidents involving
serious collisions and casualties at an intersection drops significantly
after implementation of a roundabout. This is the result of a
combination of factors: lower traffic speeds; drivers only make right
turns; traffic flows in one direction virtually eliminating the potential for
serious right-angle and head-on collisions; and roundabouts have fewer
conflict points than the conventional intersection.
• Traffic flow - Roundabouts, when implemented under the appropriate
conditions, maintain traffic flow as vehicles on all approaches are only
required to yield to vehicles present in the roundabout. Whereas a
conventional intersection (signalized or stop controlled) will always
require that vehicles come to a complete stop, thus interrupting the flow
of traffic. Other than the benefit of convenience to the motorists, this
also has environmental benefits such as lowered vehicle emissions through reduced stops and
delays and lower noise pollution as fewer vehicles are required to accelerate from a stop.
The Town has identified two intersections within the immediate study area for roundabout
consideration - the intersection of Mountain Road with Tenth Line and the intersection of Sixth Street
with Tenth Line. The roundabout option has been evaluated for both intersections and compared to
the operations of the conventional intersection. The roundabout analysis is based on single lane
approaches, and procedures outlined in the 2010 Highway Capacity Manual 7 (using Synchro v.8
software). For roundabouts, the results are displayed in the form of average delay (measured in
seconds), level of service (LOS) and volume to capacity (v/c) for each approach (LOS definitions for
signalized, unsignalized and roundabout intersections are provided in Appendix B).
4.3.1 Mountain Road & Tenth Line
As previously noted, this intersection has been identified by the Town for signalization. This study
supports this recommendation and considers signalization in the operational analysis of the
intersection under both 2020 and 2030 background conditions (presented in Table 10 and Table 12).
It is understood that the initial signals for this intersection will be temporary. In consideration of a
permanent solution, the roundabout option was investigated and compared to the conventional
7 Highway Capacity Manual. Transportation Research Board, Washington DC, 2010.
Transportation Study
Town of Collingwood
Page 30
July 9, 2012