Santa Barbara - Five Points Roundabout
- Santa Barbara, CA
- First roundabout located on a state highway system.
The reason it is called the Five Points Roundabout is that there are five legs of the roundabout. It was constructed in 1992 and then finalized in 1993. The original problem with the intersection was that 5 streets came together into a stop sign regulated intersection, creating heavy congestion and huge delays at peak hour. The average delay was 40 seconds, providing a Level of Service (LOS) of D to E. The stop sign intersection of five streets made it hard for drivers to take turns in an organized fashion. The confusion would often cause vehicles to collide at the middle of the intersection. Now the intersection is much safer and there is a 4.5-second average delay, providing a LOS of A. The roundabout cost $250,000 to construct.
The Five Points Roundabout has a diameter of 26.2 meters (86 ft.). All other roundabouts in the U.S. have an outer curb diameter of 30.5 meters (100 ft.) or greater, making this the smallest roundabout in the United States. Santa Barbara’s transit buses use the roundabout for one of the city’s bus routes. Large trucks can also use the roundabout. With such a small diameter, it would not be expected that buses and large trucks could use the roundabout. What enables these vehicles to have the space needed to turn is the roundabout’s truck apron.
Encircling the round landscaped planter in the center of the roundabout, is a 4.3 meter (14 ft.) wide truck apron. It has an angled curb and is slightly elevated above the asphalt so wide vehicles that need more space to turn to can use this space as well as the road. The truck apron is made of red and yellow tile to distinguish it from the road, and to make it more aesthetically appealing.
Good Deflections for Each Leg
The key to designing roundabouts is to have adequate deflections for each leg coming in and to ensure that drivers will slow down before entering the roundabout. Ideally, the entering lanes should point straight to the middle of the roundabout. This forces drivers to slow down before entering. Most drivers slow as little as possible before entering, and if there is no deflection of the entering lane, dangerously high speeds can result. Good deflections can be hard to design for each entering lane, especially when there are more entering legs, and a perfectly round design is desired. Five Points Roundabout has good deflections, considering it has 5 entering legs and a perfectly round design.
Landscaped planter in center of roundabout, angled-curb islands between entering and exiting lanes.
None besides the landscaped planters.
One of the main purposes of designing the roundabout was to improve the safety of the intersection. Accidents have decreased by 75 percent with the roundabout. Accidents with pedestrians have never been a problem in this location. It is a residential neighborhood with very few pedestrians.
This is Santa Barbara’s first roundabout. Before the roundabout was constructed, people strongly opposed the idea. Most people were unfamiliar with roundabouts and therefore they had no confidence in them. 90 percent of people opposed the idea of a roundabout, and 10 percent supported it. Now after a couple years of proven success, everyone likes it.
Transportation Philosophy of the Town
Santa Barbara seeks to maintain a well balanced system of transportation. They promote alternative modes of transportation, try to avoid large arterial roads, and focus on creating a system where all modes of transportation complement each other.
Not only did the roundabout improve the safety of the intersection, but it also eliminated stop and go emissions, therefore decreasing air pollution. Noise from stop and go driving was also decreased by the roundabout design. Traffic volumes are given below.
Traffic Volumes for Five Points Roundabout
1300 vehicles / hour
1500 vehicles / hour
15,000 vehicles / day
3 West Carrillo Street, Suite 208
Santa Barbara, CA 93101
fax (805) 564-2040
This information originally compiled by Eric Spangler, 1999, as part of a senior project.