Roundabouts

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Roundabouts

- General Info

- Excerpts From City of Davis General Plan

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General Info

While Roundabouts have been used in the US for many decades, they are somewhat un-common in the US today. And as usual, anything un-usual must work hard to overcome ordinary "old school" thinking.

However, due to their many attributes (including better safety and traffic flow), Roundabouts are enjoying emerging popularity in the US.

In many situations Roundabouts offer reduced traffic delays when compared to traffic lights because they keep the traffic flowing. Pollution is reduced because dramatically fewer vehicles are wasting fuel while idle and during acceleration from a dead stop. This also lowers noise levels, and driver frustration levels, while discouraging speeding and improving both pedestrian and vehicular safety.

Excerpts from the City of Davis, California General Plan

Roundabouts have been utilized in Davis at selected intersections since 1997. Roundabouts are an alternative to other traffic control devices, such as traffic signals or "all-way stop" treatments.

Although roundabouts have been in use in Europe, Australia, and South Africa for many years, they were relatively unknown in the United States until recently. Roundabouts increase the capacity of an intersection (compared to traffic signals), reduce and simplify vehicular conflicts, reduce operating speeds within the intersection, and provide refuge areas for pedestrians. In addition, the severity of crashes that may occur are reduced due to the relative angle of vehicles operating within the roundabout. Generally, roundabouts are less expensive to construct than traffic signals, and do not have the on-going costs (electricity, lamp replacement, etc.) associated with signals.

Some pedestrians and/or bicycle drivers may find a roundabout "daunting" the first time one is encountered, but navigation through the intersection is actually quite simple. Bicycle drivers should merge from the bike lane (or right side of the roadway where bike lanes are absent) into the entry lane of the roundabout. Like other vehicles, the bicycle driver must yield to vehicles already in the circulating roadway prior to entering the intersection.

In a properly designed roundabout, operating speeds for motor vehicles are reduced to 15-18 miles per hour, allowing most experienced bicycle drivers to feel comfortable "taking the lane" as if they were a motor vehicle. This is important to avoid being in the position where they could be "cut off" by a right-turning motorist. Once in the circulating roadway of the roundabout, bicycles and other vehicles proceed in a counter-clockwise direction to the appropriate exit lane.

Roundabouts also provide additional protection to pedestrian movements at the intersection. Crosswalks generally run through the "splitter islands," which are designed to deflect vehicle movements (motor and bicycle) entering and exiting the roundabout. Pedestrians cross only one traffic lane at a time, and motorists have no other conflicts that could distract their attention from the crosswalk area. Davis has developed a policy of using only single-lane roundabouts at this time, as multi-lane roundabouts tend to have problems related to bicycle movements in the intersection.

The City of Davis Currently has 5 roundabouts. 2 in significant traffic situations (Anderson & Alvarado; 5th Street at the Police Dept), plus one very near Patwin Middle School (Shasta Drive and Olympic Drive) which handles the typical "school rush" traffic peaks. And two more on a significant collector street (Moore Avenue)

Photos

Draft Oregon Graphic